568 Questions
Which of the following is NOT a characteristic of the plasma membrane?
It is permeable to all types of molecules.
What is the primary function of osmosis?
To equalize the concentration of a solution
What type of transport does not require energy?
Passive transport
What is the name of the proteins that allow passive movement of solutes through the membrane?
Channel proteins
What is the term for the movement of water through a semi-permeable membrane to equalize the concentration of a solution?
Osmosis
What is the term for the movement of molecules from an area of higher concentration to an area of lower concentration?
Diffusion
What is the term for the proteins that allow specific substances to pass through the membrane?
Carrier proteins
What is the term for the movement of molecules through a membrane with the assistance of transport proteins?
Facilitated diffusion
What is the main function of biological membranes in terms of water movement?
To act as a barrier for water movement
What is the term for the ability of a biological membrane to allow certain molecules to pass through while keeping others out?
Selective permeability
What is the function of the phosphate group in the phospholipid bilayer?
To interact with the watery environment
What is the result of a cell being placed in a hypotonic solution?
The cell will swell
What is the role of membrane transport proteins in biological membranes?
To control the movement of substances into and out of cells
What is the term for the process by which cells regulate the amount of water in their surroundings?
Osmoregulation
What is the function of the lipid tails in the phospholipid bilayer?
To remain water-resistant
What is the role of cell adhesion in biological membranes?
To facilitate the interaction between cells
What is the main function of aquaporin proteins?
To form pores that allow passage of movement of water by osmosis
What is the purpose of Na+/K+-ATPase pumps?
To move 3 Na+ out and 2 K+ into the cell
What is the term for the movement of molecules from an area of high concentration to an area of low concentration?
Passive transport
What is the name of the process by which cells take in material from outside the cell?
Endocytosis
What is the term for a solution that has the same osmotic pressure as the cell?
Isotonic
What is the term for a solution that has a higher osmotic pressure than the cell?
Hypertonic
What is the purpose of intravenous fluid therapy?
To maintain the body's electrolyte balance
What is the term for the accumulation of excess water in the tissues?
Oedema
What is the term for the movement of water out of a cell?
Cytolysis
What is the term for a carrier protein that binds to multiple molecules and transports them across the cell membrane?
Symporter
What is the primary purpose of receptors in cell signaling?
To bind to the signal or ligand and produce a response
What is the role of second messengers in cell signaling?
To transmit signals from receptors to effector proteins
What is the primary function of intercellular signaling?
To communicate between cells
What is the term for the communication between cells?
Intercellular signaling
What is the primary function of receptors in intercellular signaling?
To bind to the signal or ligand and produce a response
What is the term for the process by which cells respond to changes in their environment?
Cell signaling
What is the primary function of intracellular signaling?
To respond to changes in the cell's environment
What is the term for the proteins that enable cell-cell communication?
Receptors
What type of signaling involves a special structure called a synapse?
Synaptic signalling
What type of molecule is secreted by the target cell in autocrine signalling?
Prostaglandin
What is the main difference between autocrine, paracrine, and endocrine signalling?
Distance of signal transmission
What is the function of the synapse in synaptic signalling?
To transmit the signal
How do cells respond to signals in autocrine signalling?
By secreting signal molecules
What type of signalling occurs between neuron cell and effector cells?
Synaptic signalling
What is the primary function of gap junctions in cell-to-cell communication?
To allow direct transfer of ions or small molecules between cells
What is the characteristic of lipophilic hormone molecules?
They are lipophilic and bind to intracellular receptors
What is the primary function of paracrine signaling?
To allow local signaling between adjacent cells without entering the blood circulation
What is the characteristic of autocrine signaling?
Signaling within a single cell
What is the primary function of connexons in gap junctions?
To form a hydrophilic channel that allows direct communication between cells
What is the characteristic of hydrophilic hormone molecules?
They are hydrophilic and bind to surface receptors
What is the primary function of endocrine signaling?
To produce hormones that travel through the blood stream to distant cells
What is the characteristic of direct signaling?
Signaling between adjacent cells through gap junctions
What is the primary function of the coagulation cascade?
To form a fibrin clot
What is the result of an imbalance in the coagulation and fibrinolytic cascades?
Either excessive clotting or excessive bleeding occurs
What is the primary function of the fibrinolytic cascade?
To break down fibrin clots
What are the four necessary steps for hemostasis to be achieved?
Reflex vasoconstriction, initial platelet plug, coagulation cascade, fibrin stabilisation
What is the purpose of the kinin cascade?
To regulate inflammation
What is the primary function of the complement cascade?
To regulate inflammation
What is the result of the coagulation cascade?
A stable fibrin clot
What is the primary function of the plasma proteinase cascades?
To form a fibrin clot
What is the primary response of platelets when they come into contact with extravascular material?
They change shape, degranulate, and aggregate
What is the main function of tissue factor in secondary haemostasis?
To activate the extrinsic coagulation cascade
What is the end result of the coagulation cascade?
The formation of a solid permanent plug
What is the role of thrombomodulin in counter-regulatory mechanisms?
To inhibit the coagulation cascade
What is the primary function of t-PA in counter-regulatory mechanisms?
To generate fibrinolytic plasmin
What is the ultimate goal of counter-regulatory mechanisms?
To restrict the haemostatic plug to the site of injury
What is the relationship between the coagulation cascade and the fibrinolytic cascade?
They are complementary
What is the net result of the counter-regulatory mechanisms?
Restricted coagulation
What is the primary function of platelet adhesion and activation in primary haemostasis?
To form a temporary primary haemostatic plug
Which of the following proteins is involved in the fibrinolytic cascade?
Plasmin
What is the primary function of the coagulation cascade?
To form a blood clot
What is the primary function of the kinin cascade?
To regulate blood pressure
What is the primary function of the complement cascade?
To release inflammatory mediators
What is the primary function of albumin in plasma?
To transport proteins and hormones
What is the primary function of the fibrinolytic cascade?
To break down fibrin clots
What is the primary function of endothelin release in primary haemostasis?
To cause vasoconstriction
What is the primary function of the action potential?
To generate electrical signals in response to stimuli
What is the primary function of the resting membrane potential?
To maintain the electrical potential difference between the inside and outside of the cell
What is the role of neurotransmitters in nerve conduction?
To convert electrical signals to chemical signals across the synapse
What is the primary function of the synapse?
To allow for communication between cells through the release of neurotransmitters
What determines the conduction velocity of nerve impulses?
The diameter of the axon
What is the primary function of membrane potential in nerve conduction?
To maintain the electrical potential difference between the inside and outside of the cell
What is the primary function of the voltage-gated Na+ channels in action potential generation?
To depolarize the cell membrane
What is the primary function of the voltage-gated K+ channels during action potential generation?
To repolarize the cell membrane
What is the primary function of the Na+/K+ pump during the resting state of the neuron?
To maintain the resting membrane potential
What is the primary function of the synapse in synaptic signaling?
To allow communication between neurons or between neurons and effectors
What is the primary function of myelin in nerve conduction?
To increase the nerve conduction velocity
What is the primary function of the refractory period during action potential generation?
To allow the neuron to respond to subsequent stimuli
What is the primary function of the axon in nerve conduction?
To propagate the action potential
What is the primary function of the Ranvier nodes in nerve conduction?
To propagate the action potential
What is the primary function of neurotransmitters in the synapse?
To transmit signals from a neuron to another neuron or target cell across a synapse
What is the result of the influx of Na+ ions in the action potential?
Depolarization
Which type of nerve fibers are responsible for transmitting sharp, localized pain?
Aδ fibers
What is the mechanism of action of local anesthetics?
Blocking the influx of Na+ ions
What is the primary function of excitatory neurotransmitters?
To increase the likelihood of the postsynaptic neuron firing
What is the role of γ-aminobutyric acid (GABA) in the synapse?
To decrease the likelihood of the postsynaptic neuron firing
What is the primary function of the synapse?
To transmit signals from one neuron to another or to a target cell
What is the result of the binding of lignocaine to voltage-gated Na+ channels?
Blockade of the influx of Na+ ions
What is the site of collagen maturation?
Extracellularly
What is the characteristic of elastin that allows it to act like a 'rubber band'?
Hydrophobic uncoiling domains
What is the main cause of oral submucosal fibrosis?
Chronic consumption of areca nut
What is the primary function of glycosaminoglycans in the extracellular matrix?
Attract and trap water
What is the characteristic of proteoglycans?
Long, unbranched polysaccharides
What is the result of the strong negative charge of glycosaminoglycans?
Attraction and trapping of water
What is the significance of proteoglycans and glycosaminoglycans in the extracellular matrix?
Maintain tissue hydration and pressure
What is the characteristic of elastin that allows it to function like collagen?
Hydrophobic uncoiling domains
Which of the following glycosaminoglycans is not sulphated?
Hyaluronic acid
What is the primary function of proteoglycans in the extracellular matrix?
To regulate a wide range of biological activities
What is the characteristic of hyaluronic acid that makes it a 'goo' molecule?
Its extremely long chains
What is the primary location of heparan sulphate synthesis?
Golgi apparatus
What is the primary function of proteoglycans in the extracellular matrix, besides regulating biological activities?
To act as the 'filler' of ECM space
What is the primary difference between hyaluronic acid and heparan sulphate?
Their sulphation levels
What is the primary function of Matrix Metalloproteinases (MMPs)?
To break down extracellular matrix proteins
What is the main difference between Loose Connective Tissue and Dense Connective Tissue?
The arrangement of collagen fibers
What is the function of Hyaluronidase?
To break down hyaluronic acid
What is the primary function of Tendons?
To connect bones to muscles
What is the main component of the extracellular matrix in Bone?
Calcified collagen
What is the function of Osteoclasts in Bone Remodeling?
To break down bone matrix
What is the primary function of Adipose Tissue?
To store energy in the form of triglycerides
What is the main component of the extracellular matrix in Connective Tissue?
Collagen
What is the function of Serine Proteinases?
To break down extracellular matrix proteins
What is the primary function of Connective Tissue?
To provide structural support to organs
What is a characteristic of epithelial cells?
They are tightly bound together.
What is a function of epithelial cells in the small intestine?
Absorption of nutrients
What is a characteristic of the transformation zone in the vagina to cervix?
It is vulnerable to HPV invasion and subsequent immortalisation of cervical epithelial cells
What is a function of epithelial cells in the lung alveolus?
Gas exchange
What is a function of epithelial cells in the kidneys?
Excretion of waste products
What is a characteristic of epithelial cells in general?
They have distinct polarity
What is the characteristic of the Stratified squamous epithelial tissue?
It has multiple layers of cells with the apical surface exposed to a cavity or the outside environment.
What is the role of desmosomes in epithelial tissue?
To anchor intermediate filaments to the cell membrane
What is the function of hemidesmosomes in epithelial tissue?
To anchor cells to the basement membrane
What type of epithelial tissue is present in the skin?
Squamous
What is the characteristic of pseudostratified epithelial tissue?
It appears stratified but all cells are in contact with the basement membrane.
What is the function of the basement membrane in epithelial tissue?
To separate the epithelium from the underlying connective tissue
What type of epithelial tissue is present in the intestines?
Columnar
What is the function of keratin intermediate filaments in epithelial tissue?
To provide mechanical strength to the tissue
What covers the outside of the body and invaginations of the gastrointestinal, respiratory, renal, and reproductive systems?
Epithelial tissue
What is the primary characteristic of epithelial cells that allows them to serve structural and endocrine functions?
Specialization
What type of filaments are present in epithelial cells?
Keratin
What is the function of epithelial cells in the skin?
To regulate water loss
What is the characteristic of epithelial cells that allows them to be tightly packed together?
Cell adhesion
What is the main difference between skin and buccal epithelia?
Location
What is the function of epithelial cells in the respiratory system?
To facilitate gas exchange
What is the primary function of epithelial cells in the body?
To line and cover body surfaces
What percentage of the genome consists of non-coding DNA?
98%
What is the term for the complete set of chromosomes in a cell?
Karyotype
What is the primary function of histone proteins?
To form chromatin with DNA
What is the approximate number of base pairs of DNA in a human cell?
3.0 x 10^9
What is the term for the center of a chromosome?
Centromere
What is the term for the end of a chromosome?
Telomere
What is the function of RNA polymerase in transcription?
To form RNA from DNA template
What is the result of a silent mutation?
A codon that still codes for the same amino acid
What is the genetic code?
A dictionary that links RNA sequence to an amino acid
What is the function of microRNA?
To regulate gene expression
What is the function of tRNA?
To bring amino acids to the ribosome during translation
What is the result of a missense mutation?
A codon that codes for a different amino acid
What is the function of rRNA?
To form the ribosome
What base is present in RNA but not in DNA?
U
What is the correct sequence of genetic information flow during cell growth and replication?
DNA → RNA → Protein
What is the process of synthesizing RNA from DNA called?
Transcription
What is the main difference between prokaryotes and eukaryotes in terms of gene transcription?
Eukaryotes have separate mRNA molecules for each gene, while prokaryotes have multiple genes on one mRNA
What is the result of the central dogma?
The creation of proteins from RNA
What is the term for the synthesis of proteins from RNA?
Translation
What is the characteristic of RNA molecules compared to DNA molecules?
RNA molecules are shorter than DNA molecules
What is the term for the process of creating RNA from DNA?
Transcription
What is the result of the flow of genetic information during cell growth and replication?
The creation of gene products
What is the primary function of the somites in embryonic development?
Development of muscle, bone and cartilage
At what stage of development do the pharyngeal arches begin to form?
Day 22
What is the purpose of the pharyngeal pouches in embryonic development?
Separation of the arches
What is the relationship between the pharyngeal arches and the pharyngeal grooves?
Pharyngeal arches form on the endodermal side, while pharyngeal grooves form on the ectodermal side
What is the characteristic of the pharyngeal arches?
Contain muscle, cartilage, and cranial nerves
What is the significance of the hindlimb and forelimb buds in embryonic development?
They will eventually develop into the limbs
Which of the following muscles develop from the first pharyngeal arch?
Masticatory muscles and anterior belly of digastric
What is the origin of the cartilage and bone in the pharyngeal arches?
Neural crest cells
Which of the following cranial nerves develop from the first pharyngeal arch?
Trigeminal nerve
What is the result of the failure of fusion of the maxillary process and the mandibular process?
Unilateral cleft lip
What is the name of the process by which the frontonasal process forms the nasal septum and the nasal pits?
Facial development
Which of the following structures develop from the fourth pharyngeal arch?
Larynx
What is the name of the process by which the palatal shelves elevate and fuse to form the hard palate?
Palate development
What is the result of the failure of fusion of the medial nasal processes?
Median cleft lip
Which of the following structures develop from the second pharyngeal arch?
Stapes
What is the name of the process by which the somites develop into the muscles of the pharynx?
Somite development
What is the approximate time frame when the mid-palatal suture ossifies?
12-14 years
What is the ratio of males to females in the occurrence of cleft lip with cleft palate?
2:1
What is the term for the failure of fusion of the palatal shelves with the tectal ridge?
Cleft palate
What is the name of the type of cleft that involves the hard or soft palate, but appears intact with muscle and bone deficits?
Submucous cleft
What is the approximate frequency of occurrence of cleft lip with cleft palate?
1 in 1600
What is the process by which the epithelial cells undergo transformation to allow the fusion of the processes?
Epithelial mesenchymal transformation
What is the term for the cleft that occurs anterior to the incisive foramen?
Cleft involving primary palate
What is the ratio of males to females in the occurrence of cleft palate?
1:2
What is the approximate time frame when the maxilla forms through intramembranous ossification?
8 weeks of intrauterine life
What is the term for the type of cleft that occurs posterior to the incisive foramen?
Cleft involving secondary palate
What is the primary driver of tooth eruption according to the study?
Bite forces sensed by dental follicles
What type of analysis was used to study tooth eruption in the study?
Finite element analysis
What is the title of the journal where the study was published?
PLoS One
Who is the author of the study?
Prof Hans Zoellner
What is the year of publication of the study?
2013
What is the volume number of the journal where the study was published?
8
What is the first stage of tooth development?
Initiation Stage
What is the function of the dental lamina in tooth development?
It provides a pathway for the growth of the tooth
What is the structure that forms in the Bud Stage of tooth development?
Bud
What is the term for the structure that forms in the Early Bell Stage of tooth development?
Enamel organ
What is the structure that forms in the Late Bell Stage of tooth development?
Cervical loop
What is the term for the process by which the root of the tooth forms?
Root formation
What is the term for the cells that form the dentine of the tooth?
Odontoblasts
What is the structure that forms in the Root Formation Stage of tooth development?
Hertwig’s Epithelial Root Sheath
What is the term for the cells that form the cementum of the tooth?
Cementoblasts
What is the term for the cells that remain in the periodontal ligament after tooth development?
Rests of Malassez
What forms the connection between the tooth and the surrounding bone tissue?
Periodontal Ligament
What is the stage of tooth development where the enamel epithelium is reduced?
Late Bell Stage
What is the term for the junction between the dentine and enamel?
Dentine-Enamel Junction (DEJ)
What is the type of dentine that forms first?
Primary Dentine
What is the function of the ameloblasts?
To produce enamel
What is the term for the layer of cells that forms the outer layer of the enamel organ?
Outer Enamel Epithelium
What is the term for the strands of collagen that form the dental lamina?
Back-Growth of Dental Lamina
What is the name of the process by which the dental pulp is formed?
Dental Pulp Formation
What is a characteristic of bacteria?
They have a cell wall containing peptidoglycan.
What is an example of a disease caused by bacteria?
All of the above
What is a characteristic of fungi?
They are a diverse group with 90,000 identified species.
What type of organisms are Porphymonas gingivalis?
Bacteria
What is a characteristic of prokaryotes?
They are single-celled.
What is a common habitat of bacteria?
Ubiquitous in the environment and on humans
What is a role of fungi in the human body?
They can cause oral thrush
What is a characteristic of Gram-stain of coliforms?
They have parallel sides and rounded ends
What is the percentage of worlds oxygen produced by algae and cyanobacteria?
50%
Which of the following is a human disease caused by a protist?
Malaria
What is the simplest form of a virus?
Protein + Nucleic acid
What type of disease is caused by viroids?
Plant diseases
What is the term for infectious proteins?
Prions
Which of the following is not a characteristic of viruses?
They are living entities
What is the main difference between archaea and bacteria?
Cell wall composition
Why is it important to know about different microorganisms?
To understand the importance of microorganisms in the environment
What is the first requirement of Koch's postulates?
The micro-organism must be present in every disease and absent in every health case
What is a characteristic of Archea and Bacteria?
They are prokaryotes
Which of the following is NOT a reservoir of microbes?
Atmosphere
What is the characteristic that distinguishes cellular from acellular microbes?
Cellular structure
Which of the following microorganisms can cause disease?
All of the above
What is a function of microbes?
They make life possible
What is an example of a zoonosis?
Rabies
Which of the following is an example of a fungus?
Slime moulds
What is the term for the movement of water through a semi-permeable membrane to equalize the concentration of a solution?
Osmosis
What is the term for a microbe that can cause disease in humans?
Pathogen
What is the definition of micro-organisms?
Organisms that are less than 1mm in diameter
What is a characteristic of viruses?
They are acellular
Which of the following is an example of a protist?
Algae
Which of the following is an example of an acellular microbe?
Virus
Who is the presenter of the introduction to microbes course?
Prof Vitali Sintchenko
What is the main function of Koch's postulates?
To identify the cause of a disease
What is the name of the textbook that covers bacterial morphology and nomenclature?
Eds: Joanne Willey, Linda Sherwood, Chris Woolverton
What is one of the learning objectives of the introduction to microbes course?
To detail the different classes of micro-organisms
What is the topic of lecture 4 in the course?
Host microbe interaction
Why are micro-organisms important?
They are involved in human disease
What is the name of the textbook that covers oral microbiology?
Oral Microbiology
Who originally developed the introduction to microbes course?
Dr Christina Adler
What is the primary function of the Linnaean naming convention?
To determine the genus and species of an organism
What is the characteristic of Streptococcus species?
They are spherical in shape
What is the purpose of a phylogenetic tree?
To represent the evolutionary relationships between organisms
What is the difference between genus and species?
Species refers to a collection of strains, while genus refers to a group of species
What is the characteristic of diplococci?
They are spherical in shape and occur in pairs
What is the primary function of genomic similarity in bacterial classification?
To classify bacteria based on their DNA sequences
What is the characteristic of staphylococci?
They are spherical in shape and occur in clusters
What is the primary function of a phylogenetic tree in bacterial classification?
To represent the evolutionary relationships between bacteria
What is the characteristic of Bacteroidetes?
Gram negative and rod shaped
Which of the following bacteria is associated with disease?
Both A and B
What type of bacteria does not have a cell wall?
Some bacteria
What is the significance of Gram staining?
It is used to classify bacteria based on the composition of their cell walls
What is the significance of the shape of bacteria?
It is used to classify bacteria based on their shape, such as rods, cocci, or spirilla
What is the significance of respiration in bacterial classification?
It is used to classify bacteria based on their metabolic capabilities
What is the significance of the nomenclature of bacteria?
It is used to identify and classify bacteria using a universal system
What is the significance of historical criteria in bacterial classification?
It is used to classify bacteria based on their Gram stain reaction and shape
What is the primary purpose of Gram staining in microbiology?
To distinguish between Gram-positive and Gram-negative bacteria
What is the term for the spiral-shaped bacteria?
Spirochaetes
Which of the following is an example of bacterial arrangement?
Clumps
What is the purpose of a phylogenetic tree in microbiology?
To understand the evolutionary relationships between organisms
Who is credited with developing the system of naming organisms?
Carl Linnaeus
What is the term for the round or spherical bacteria?
Cocci
Why is it important to focus on bacteria in oral health?
They are numerically the most dominant cells in the oral cavity
What is the term for the movement of molecules from an area of higher concentration to an area of lower concentration?
Diffusion
What type of bacteria growth is allowed by semi-solid media?
Microaerophilic
What is the purpose of measuring optical density at 600 nm?
To quantify bacterial growth
What is the advantage of using solid media for bacterial growth?
Allows for the isolation of single colonies
What is the purpose of serial dilution and plating on agar?
To enumerate colony-forming units
What is the purpose of qPCR in bacterial quantification?
To quantify bacterial growth
What is the advantage of using liquid media for bacterial growth?
Allows for uniformed growth until nutrient limitation
What is the primary way bacteria grow and replicate?
By binary fission
What is the optimal temperature for bacterial growth?
37oC
What type of bacteria requires oxygen for growth?
Strict aerobes
What is the purpose of additives in culture media?
To enrich or inhibit certain bacteria
What is the difference between defined and complex culture media?
Defined media has an exact composition, while complex media has an unknown composition
What type of bacteria prefers oxygen for growth, but can grow without it?
Facultative aerobes
What is the purpose of culture media in a laboratory?
To provide a substance that supports the growth of bacteria
What type of bacteria cannot grow in the presence of oxygen?
Strict anaerobes
What is the primary characteristic of the Lag phase in a bacterial growth curve?
Bacteria are adapting to new environment and replicating chromosomes
In the oral environment, which phase corresponds to the period of fasting in between meals?
Stationary phase
What is the primary characteristic of the Exponential phase in a bacterial growth curve?
Cells are growing and dividing maximally
What is the primary characteristic of the Death phase in a bacterial growth curve?
Cells stop growing and die even when supplied with new medium
In the oral environment, which phase corresponds to the period immediately after a meal?
Lag phase
What is the primary characteristic of the Stationary phase in a bacterial growth curve?
Cell numbers stop increasing and DNA replication is arrested
In the oral environment, which phase corresponds to the period when bacteria are susceptible to antimicrobials?
Stationary phase
What is the primary function of the proteins produced during the Stationary phase?
To enhance cell survival during starvation
What is the term for a state of infection that results in no damage to the host?
Commensalism
What is the term for the collection of microorganisms that share our body space?
Microbiome
What is the term for the relationship between two organisms where both benefit?
Mutualism
What is the term for the acquisition of microorganisms by the host?
Colonization
What is the term for an organism that consists of a host and its microbiome?
Holobiont
Why are commensal microorganisms beneficial to humans?
They protect us from foreign substances and pathogens
What is the approximate ratio of microbial cells to human cells in the human body?
10^4:10^3
Where are commensal microorganisms typically found in the human body?
Skin, oral, respiratory, and gastrointestinal tracts
What is the primary function of the human microbiome?
To protect the host against pathogens and provide nutrients
What is unique about the 16S ribosomal RNA sequencing?
It has a slow rate of evolution and is highly-conserved between bacteria and archaea
What is the difference between culture-dependent and culture-independent methods?
Culture-dependent methods require culturing, while culture-independent methods do not
What is the goal of shotgun metagenomics?
To sequence every nucleic acid within a given sample
What is a characteristic of the human microbiome?
It has a huge diversity in composition
What is a limitation of traditional microbiology techniques?
Most microorganisms cannot be cultured
What can metagenomics be used for?
Insights into population dynamics
What is a characteristic of the skin microbiota?
High salt content
What is a function of bacteria on the skin?
Producing body odour
Where can metagenomics be applied?
Host microbiome
What can be characterised using metagenomics?
All of the above
What is the environment like on the superficial skin?
Slightly acidic
What is the term used to describe the relationship between humans and microbes?
Holobionts
What is the effect of the microbiome on caloric absorption in mice?
Increases caloric absorption
What is an example of a disease caused by microbiome dysbiosis?
All of the above
What is the term used to describe the state of the microbiome when it is out of balance?
Dysbiosis
What is the characteristic of the microbiome across the human body?
It is diverse and in flux
What is the effect of a germ-free diet on mice?
They gain less weight
What is the role of microbes in the body?
They can be either beneficial or harmful
What is the term used to describe the relationship between the microbiome and fat storage?
Environmental factor
In which part of the gut does the highest diversity of microbiota exist?
Large intestine
What is one of the symbiotic relationships of the gut microbiota?
Produce biotin and vitamin K
What is a characteristic of the oral microbiota after tooth eruption?
Increase in anaerobes
What is the relationship between the oral microbiota and taste perception?
The oral microbiota alters taste perception
What is the result of changes to the oral microbiota on human health?
Decreased blood pressure
What is the characteristic of the stomach microbiota?
Highly acidic with few viable bacteria
What is the role of the gut microbiota in preventing pathogen colonization?
They compete with pathogens for nutrients
What is the characteristic of the small intestine microbiota?
Highly acidic with few viable bacteria
What is the term used to describe the symbiotic relationship between humans and microorganisms?
Holobiont
What is the main characteristic of the stomach in terms of gut microbiota?
Highly acidic with few viable bacteria
Which of the following is an example of dysbiosis?
All of the above
What is the role of the gut microbiota in the large intestine?
To prevent pathogens from colonizing and absorb nutrients
What is the factor that regulates fat storage, according to Bäckhed et al.?
Microbiota
When does the mouth become colonized with microbiota?
Soon after birth
Which of the following is NOT a characteristic of the microbiome?
Constant and unchanging
What is the role of the oral microbiota in taste perception?
To alter taste perception
What is the result of having a germ-free (GF) versus conventional mice, when fed the same diet?
GF mice gain less weight
What is the term used to describe the state of balance and stability in the body's internal environment?
Homeostasis
What is the characteristic of the small intestine in terms of gut microbiota?
Acidic with bile juices and few viable bacteria
What is the term used to describe the community of microorganisms that inhabit the human body?
Microbiome
What is the role of the gut microbiota in the large intestine?
To prevent pathogens from colonizing and absorb nutrients
What is the characteristic of the large intestine in terms of gut microbiota?
Highly diverse with 10^12 cells/gram stool
What is an example of a dental condition caused by microbiome dysbiosis?
All of the above
What is the result of changes to the oral microbiota?
Modulation of nitric oxide homeostasis and blood pressure
What is the term for the state of infection that results in no damage to the host?
Commensalism
What is the term for the collection of microorganisms that live within and on the human body?
Microbiome
What is the term for the relationship between the host and microbe where both benefit?
Mutualism
What is the approximate ratio of microbial cells to human cells in the human body?
10^14:10^13
What is the term for the acquisition of micro-organisms by the host?
Colonization
What is the term for the beneficial tasks performed by the microbiome?
Protection from foreign substances and pathogens
What is the term for the collection of microbial cells that live on the skin and in the oral, respiratory and gastrointestinal tracts?
Commensals
What is the term for the host and its associated microbiome?
Holobiont
What can metagenomics be used for?
Insights into population dynamics
What characterizes the environment on superficial skin?
High salt, low water content, and inhibitory substances
What is a result of bacterial degradation of skin oil?
Body odor
What can be characterized through the use of metagenomics?
Microbial communities, including DNA and/or RNA from bacteria, viruses, fungi, and the host
What is a feature of the respiratory microbiota?
High bacterial diversity in the lungs
What can be analyzed through metagenomics?
Extended characterization of the microbial community, including subtyping, AMR genes, and virulence genes
What is one of the functions of the microbiome?
To protect the host against pathogens
What is characteristic of the 16S rRNA gene?
It is highly conserved between bacteria and archaea
What is the main difference between culturable and non-culturable microorganisms?
Culturable microorganisms can be grown on a petri dish, while non-culturable microorganisms cannot
What is shotgun metagenomics?
A method for sequencing every nucleic acid within a given sample
What is the main advantage of using culture-independent methods in microbiome research?
They provide a more accurate view of microbial diversity
At what stage of life is the microbiome typically acquired?
During the first year of life
What is a common early coloniser in dental plaque?
Streptococci
What is a disadvantage of living in a biofilm?
Slower diffusion of nutrients
What is a mechanism by which bacteria exchange DNA to tolerate acidic conditions?
Horizontal gene transfer
What is a protein toxin produced by bacteria that can help prevent URT infections?
Bacteriocins
Why do chemicals tend to concentrate in biofilms?
Due to the structure of the biofilm
What is a characteristic of bacteria that produce bacteriocins?
They produce narrow-spectrum antimicrobial proteins
What is an advantage of living in a biofilm?
Increased resistance to environmental stress
What is the physiology of the oral biofilm a reflection of?
The activity of the entire microbial community
At six months, what is the significant event that influences the oral microbiome?
Tooth emergence
What is the primary advantage of biofilm formation in the oral cavity?
Increased diversity of nutrients for the microbial community
Which bacteria are increasingly abundant during the period of tooth emergence?
Fusobacterium, Lactobacillus, Neissera, Gemella, and Haemophillius
What is the primary factor influencing the development of the oral microbiome during childhood?
Postnatal factors
What is the result of an imbalance in the oral microbiome during childhood?
All of the above
What is the primary role of the oral microbiome in maintaining oral health?
Maintaining a balance of commensal bacteria
What is the primary source of bacteria in the infant oral microbiome during the first 6 months?
Precolostrum from mothers
What is the effect of breastfeeding on the oral microbiome of infants?
Increases the abundance of Veillonella species
What is the primary advantage of living in a biofilm for oral microorganisms?
Enhanced adherence to oral surfaces
What is the primary factor influencing the development of the oral microbiome during early childhood?
Early feeding practices
What is the primary role of Streptococcus species in the oral microbiome?
Production of lactate
What is the primary mechanism of antibiotic resistance in oral biofilms?
Biofilm-mediated protection
What is the primary consequence of an imbalance in the oral microbiome?
Increased susceptibility to oral infections
What is the primary function of Veillonella species in the oral microbiome?
Utilization of lactate
What is the primary function of neutrophils in the immune system?
To kill bacteria and make pus
What is the process called when phagocytic cells move towards the source of bacterial products?
Chemotaxis
What is the role of the complement system in phagocytosis?
To coat microorganisms for recognition by phagocytic cells
What is the term for the coating of microorganisms to facilitate phagocytosis?
Opsonization
What is the role of Toll-like receptors in immunity?
To recognize bacterial products
What is the primary function of Eosinophils?
To contribute to allergy
What is the process called when neutrophils move towards the source of bacterial products?
Chemotaxis
What is the term for the sugar polymer that is a component of the bacterial cell wall?
Peptidoglycan
What is the primary function of phagocytosis?
To capture and digest foreign particles
What is the role of opsonins in the immune system?
To attach to microbes and increase phagocytosis
What is the function of chemokines in the immune system?
To attract macrophages and neutrophils to infected tissues
What is the result of defective neutrophil function?
Microbial accumulation and inflammation
Which of the following cells primarily produce myeloperoxidase?
Neutrophils, monocytes, and macrophages
What is the term for the process by which cells take in material from outside the cell?
Phagocytosis
What is the primary function of the oxygen-independent pathway in phagocytosis?
Degradation of ingested pathogens using lysosomal enzymes
Which type of cell is responsible for presenting antigens to T-cells?
All of the above
What is the primary function of chemokines in the immune response?
Recruitment of immune cells to the site of infection
Which toxin produced by Porphyromonas gingivalis corrupts adhesion complexes, allowing access of microbial products to the underlying tissue?
Toxin with structural similarity to intercellular adhesion molecules
What is the primary function of neutrophils in the immune response?
Phagocytosis and killing of microbes
What is the result of activating toll-like receptors (TLRs) in the immune response?
Production of cytokines and activation of immune responses
What type of antigens do MHC class I molecules display?
Self-antigens
What is the primary function of MHC class I and II molecules?
Presenting antigens to T-cells
Which type of immune response involves the activation of T-cells that recognize antigens displayed on MHC molecules?
Adaptive immune response
What is the role of CD28 in T-cell activation?
It provides co-stimulation to T-cells
What is the primary function of CTLA-4 in T-cell activation?
It limits T-cell expansion
What is the role of IL-2 in T-cell activation?
It promotes T-cell proliferation
What determines the specificity of adaptive immune responses?
Recognition of specific epitopes
What is the primary function of dendritic cells in adaptive immunity?
Presentation of antigens to T-cells
What is the primary function of dendritic cells in the immune response?
To process and present antigens to T-cells
What is the main difference between MHC Class I and MHC Class II?
MHC Class I is expressed on all nucleated cells, while MHC Class II is expressed only on antigen-presenting cells
What is the primary function of the innate immune response?
To reduce the pathogen load and prevent infection
What is the role of antigen-presenting cells in the adaptive immune response?
To process and present antigens to T-cells
What is the main characteristic of acquired immunity?
Provides long-term immunity against specific pathogens
What is the role of MHC molecules in antigen presentation?
To present antigens to T-cells
What type of antigens require T cell 'help'?
Soluble proteins
What is the primary function of adaptive immunity?
To provide long-term immunity against specific pathogens
What is unique about B cell receptors (BCRs)?
They recognize antigens in their native unprocessed forms
What is the role of dendritic cells in the initiation of the adaptive immune response?
To process and present antigens to T-cells
What is the result of mass apoptosis of lymphocytes in the absence of antigen presentation?
Self-limitation
What is the function of CD40 in antigen recognition?
Costimulatory molecule
What type of antibodies are produced by B1 cells?
IgM
What is the result of affinity maturation?
Decrease in the dissociation constant (Kd)
What is the primary function of the muscles of facial expression?
To allow for facial movements and expressions
Which bone makes up the majority of the skull?
Cranial bone
What is the primary function of the trigeminal nerve in the head and neck?
To enable sensation in the face and head
What is the term for the joint that connects the mandible to the skull?
Temporomandibular joint (TMJ)
What is the primary function of the muscles of mastication?
To facilitate the movement of the jaw for eating and speaking
What is the term for the study of the structure and organization of the nervous system?
Neuroanatomy
What is the primary function of the salivary glands in the head and neck?
To produce saliva for digestion and oral health
What is the term for the anatomical landmarks of the oral cavity relevant to local anesthesia?
Anatomical landmarks for local anesthesia
What is the primary aim of the Head and Neck Anatomy course for Oral Health Therapists?
To understand the anatomy of the head and neck
Why do Oral Health Therapists need to know anatomy?
To understand the anatomy of the head and neck
What is the significance of the lithograph from Joseph Maclise’s “The circulatory system” (1844)?
It shows the anatomy of the circulatory system
Who presented the lecture on Head and Neck Anatomy?
Dr Filip Vujovic DDS, PhD
What is the topic of the lecture presented by Dr Filip Vujovic DDS, PhD?
Anatomy of the Head and Neck
What is the main goal of the Head and Neck Anatomy course?
To understand the anatomy of the head and neck
Which of the following is NOT a topic covered in the Head and Neck Anatomy course?
Anatomy of the limbs
What is the significance of the Copyright Regulation WARNING?
It indicates that the material is protected by copyright
What is the term for the movement of the head towards the shoulder?
Lateral flexion
What is the term for the movement of the jaw superiorly or inferiorly?
Elevation and depression
What is the movement of the head away from the midline called?
Abduction
What is the term for the movement of the jaw forward and backward?
Protraction and retraction
What is the term for the movement of the head to one side, away from the midline?
Rotation
What is the term for the movement of a body part towards the midline?
Adduction
What is the function of the lingual papilla on the dorsal surface of the tongue?
Taste buds
Which muscle deviates the tongue to the side and pulls the tip downwards?
Inferior longitudinal muscle
What is the term for the folds of mucous membrane on the ventral surface of the tongue?
Fimbriated folds
Which extrinsic tongue muscle lifts the tongue upwards?
Palatoglossus
What is the name of the groove on the dorsal surface of the tongue that separates the oral and pharyngeal parts?
Sulcus terminalis
Which part of the tongue is firmly attached to the hyoid bone via the genioglossus and geniohyoid muscles?
Root
What is the name of the bony structure that forms the hard palate?
Palatine bone
Which intrinsic tongue muscle narrows the tongue and pulls it towards the floor of the mouth?
Transverse muscle
What is the term for the mucous membrane on the ventral surface of the tongue?
Oral mucosa
Which extrinsic tongue muscle protrudes the tongue and moves it from side to side?
Genioglossus
What is the main function of the tensor palati muscle?
Tightens the palate and pulls the auditory tube open
What is the palatine aponeurosis?
A thin, firm, fibrous sheet formed by the expanded tendon of the tensor palati muscle
What type of tissues are found in the soft palate?
Muscles, aponeuroses, and fat
How many paired palatal muscles are there?
5
What is the function of the levator palati muscle?
Lifts the palate up and back
Which of the following muscles is NOT a palatal muscle?
Genioglossus
What is the function of the orbicularis oris muscle?
To move the lips during speech
Which of the following bones forms the cheek?
All of the above
What is the name of the fold that forms the lips?
Musculo-fibrous fold
What is the function of the buccinator muscle?
To compress the cheek against the teeth
What is the colour of the gingiva?
Light coral pink to heavily pigmented
What is the name of the gland located in the cheek?
Parotid gland
What is the name of the zone where the lip skin meets the mucous membrane?
Vermillion
What is the function of the masseter muscle?
To elevate the mandible during eating
What is the name of the arch that forms the posterior border of the oral cavity proper?
Palatopharyngeal arch
What is the function of the gingiva?
To cover the alveolar processes of the maxilla and mandible
What is the term for the depression in the sphenoid bone that accommodates the pituitary gland?
Hypophyseal fossa
Which of the following bones forms the floor of the posterior cranial fossa?
Occipital bone
What is the function of the pterygoid plates?
Muscle attachment
Which of the following features is NOT associated with the sphenoid bone?
Mandible
What is the term for the region formed by the occipital bone and petrous temporal bone?
Posterior cranial fossa
What is the term for the bony structure that extends from the sphenoid bone to the basilar process of the occipital bone?
Clivus
What is the type of joint that connects most of the bones in the skull?
Fibrous joint
Which of the following bones is NOT a part of the facial skull?
Occipital
What is the term for the bony extensions from the body of a bone that articulate with other cranial bones or serve as attachments for muscles or ligaments?
Processes
How many bones form the skull?
22
What is the term for a bony bump or elevation overlying a deep structure?
Eminence
Which of the following bones is paired?
Maxilla
What is the name of the joint that is an exception to the non-moveable suture joints?
Temporomandibular Joint (TMJ)
Which of the following bones is single?
Vomer
What is the primary function of the intervertebral disc in the vertebral spine?
To reduce stress of impact and allow movement
Which of the following bones forms the floor of the anterior cranial fossa?
Frontal bone
What is the function of the cribriform plate in the ethmoid bone?
To transmit olfactory nerve filaments
What is the name of the bony crest that projects superiorly from the cribriform plate in the ethmoid bone?
Crista galli
Which of the following cranial fossae contains the pituitary gland?
Middle cranial fossa
Which of the following bones forms the posterior boundary of the middle cranial fossa?
Petrous temporal bone
What is the function of the ethmoidal air cells in the ethmoid bone?
To produce mucus in the nasal cavity
Which of the following cranial bones forms the roof of the cranium?
Calvarium
What forms the dorsum and apex of the nose?
Three main cartilages
What are the nasal bones?
Paired, thin, and form the roof of the nasal cavity
How many bones form the floor, roof, and lateral wall of the nasal cavity?
8 bones
What is the composition of the nasal septum?
Cartilaginous anteriorly and bony posteriorly
What is the location of the alveolar process with teeth?
In the oral cavity
What is the root of the nose formed by?
Three bones
Which of the following bones make up the nasal cavity?
Nasal, Vomer, and Concha
Which of the following bones are part of the orbit?
Zygomatic, Maxillary, and Lacrimal bones
Which of the following bones make up the oral cavity?
Maxilla, Mandible, and Palatine bone
Which of the following bones is NOT a part of the facial skeleton?
Occipital bone
What is the name of the bone that forms the floor of the orbit?
Maxillary bone
Which of the following bones is responsible for forming the nasal septum?
Vomer bone
Which of the following bones is NOT a part of the paranasal sinuses?
Mandible bone
What is the name of the bone that forms the roof of the nasal cavity?
Frontal bone
What is the primary function of the zygomatic bone in the facial structure?
Forming the infraorbital margin
Which of the following bones forms the medial wall of the orbit?
Lacrimal bone
What is the name of the process by which the maxilla bone articulates with other bones in the face?
Articulation
Which of the following bones is NOT a part of the nasal cavity?
Mandible
What is the name of the bony structure that forms the inferior margin of the orbit?
Infraorbital margin
Which of the following bones contributes to the formation of the oral cavity?
Mandible
What is the term for the bony structure that forms the superior and middle nasal conchae?
Ethmoid bone
Which of the following bones is a paired bone that forms the lateral wall of the orbit?
Zygomatic bone
Which of the following muscles is responsible for facial expression of sadness?
Depressor anguli oris
Which of the following is NOT a levator muscle of the face?
Buccinator
What is the origin of the zygomaticus major muscle?
Zygomatic bone
Which of the following muscles is involved in the action of frowning?
Procerus
What is the insertion of the levator labii superioris muscle?
Skin and muscles of the upper lip
Which of the following facial movements is NOT a function of the buccinator muscle?
Elevation of the corner of the mouth
What is the primary function of the muscles of facial expression?
Facilitating speech and facial expressions
What is the characteristic of muscles of facial expression in terms of their origin and insertion?
They originate from bone and insert into skin
Which of the following muscles are involved in facial expression?
Scalp/forehead/eyebrows muscles
What is the type of muscle that makes up the muscles of facial expression?
Skeletal muscle
Which of the following is NOT a category of muscles in the head and neck region?
Intercostal
What is the primary function of the muscles of the eyes in facial expression?
Creating facial expressions
Which muscle is responsible for the action of frowning?
Procerus
Which of the following muscles is NOT a paired muscle of facial expression?
Orbicularis oris
What is the origin of the frontal belly of the occipitofrontalis muscle?
Epicranial aponeurosis
What is the action of the occipitofrontalis muscle?
Surprise
Which muscle is responsible for the action of raising the eyebrows?
Frontal belly of occipitofrontalis
What is the insertion of the corrugator supercilli muscle?
Skin of the eyebrow
Which muscle is responsible for the action of depressing the eyebrows?
Procerus
What is the function of the epicranial aponeurosis?
It forms the third layer of the scalp
Which muscle is responsible for rotating the head to the opposite side?
Sternocleidomastoid
What is the name of the triangle bounded by the sternocleidomastoid muscle, the trapezius muscle, and the clavicle?
Posterior triangle
Which bone forms the lower jaw?
Mandible
What is the function of the digastric muscle?
Elevation of the hyoid bone
Which muscle is responsible for scapular rotation?
Trapezius
What is the name of the muscle that originates from the mastoid process and inserts into the occipital bone?
Sternocleidomastoid
Which muscle is responsible for elevating the hyoid bone and the floor of the mouth?
Digastric
Which triangle is bounded by the posterior border of the sternocleidomastoid muscle and the anterior border of the trapezius muscle?
Occipital triangle
Which muscle does not belong to the infrahyoid muscles group?
Mylohyoid
What is the primary function of the Sternocleidomastoid muscle?
To tilt and rotate the head
What is the location of the splenius capitus muscle?
Floor of the posterior triangle
What are the Triangles of the Neck used to describe?
The location of key features in the neck
Which of the following muscles is not a suprahyoid muscle?
Thyrohyoid
What is the main function of the trapezius muscle?
To elevate the scapula
What is the name of the bone that the Sternocleidomastoid muscle attaches to?
Mastoid process
What is the function of the Trapezius muscle?
To move the shoulder and scapula
Which muscle forms the border between the anterior and posterior triangles of the neck?
Sternocleidomastoid
Which of the following muscles is not a muscle of the posterior triangle?
Digastric
Which of the following muscles is not involved in the movement of the mandible?
Sternocleidomastoid
What is the location of the infrahyoid muscles?
Inferior surface of the hyoid bone
What is the name of the muscle that attaches to the ligamentum nuchae?
Trapezius
Which muscle is responsible for elevating the hyoid bone?
Mylohyoid
What is the location of the Parotid duct?
Lateral to the mandible
What is the name of the muscle that attaches to the external occipital protuberance?
Trapezius
Study Notes
Biological Membranes
- Biological membranes are barriers that control the movement of substances into and out of cells
- They regulate the composition within individual cells and control the flow of information between cells
- Membranes capture and release energy, are involved in cell adhesion, and synthesize steroids
Structure and Function of Plasma Membrane
- Plasma membrane is a bi-layer of phospholipids with a phosphate group (head) and two chains of fatty acids (lipid tails)
- The head is hydrophilic (water-loving) and the tail is hydrophobic (water-fearing), making the membrane amphipathic
- The membrane is selectively permeable, allowing some molecules to pass through while keeping others out
- It is permeable to lipid-soluble substances (e.g., O2) and impermeable to charged molecules (e.g., ions)
Body Fluid Balance and Distribution
- The movement of water in the body needs to be controlled to prevent swelling and dehydration
- Body fluids are distributed among intracellular fluid (~25 L), interstitial fluid (~12 L), plasma (~3 L), and extracellular fluid (ECF = plasma + interstitial fluid)
Osmosis and Water Movement
- Osmosis is the movement of water through a semi-permeable membrane to equalize the concentration of a solution
- Osmotic pressure (OP) is created by a concentration difference of dissolved substances between two sides of a bio-membrane
- Hydrostatic pressure can stop the movement of water
- The size of solute particles does not influence osmosis
Transport Across Biological Membranes
- Passive movement follows the concentration gradient and does not require energy
- Active transport moves substances against the concentration gradient and requires energy
- Diffusion and facilitated diffusion are types of passive movement
- Carrier proteins and pumps are involved in active transport
Membrane Transport Proteins
- Channels allow passive movement of solutes through the membrane
- Aquaporins are small integral membrane proteins that form pores for water movement by osmosis
- Pumps catalyze the hydrolysis of ATP to ADP and use energy for active transport
- Carriers/transporters bind specific molecules and transfer them across the membrane
Cellular Transport
- Exocytosis is the process of exporting material from the cell through vesicles
- Endocytosis is the reverse of exocytosis, taking in material into the cell
- White blood cells use endocytosis to engulf bacteria and viruses
Osmosis and Fluid Balance
- Isotonic solutions have the same concentration of dissolved substances as the cell interior
- Hypotonic solutions have a lower concentration of dissolved substances than the cell interior, causing water to move into the cell
- Hypertonic solutions have a higher concentration of dissolved substances than the cell interior, causing water to move out of the cell
- Osmosis is important in intravenous fluid therapy to maintain body fluid and electrolyte balance
Intercellular Signaling
- Cells need receptors and signaling systems to respond to changes in their immediate environment, communicate with other cells, and coordinate cellular functions.
- Intercellular signaling involves communication between cells, while intracellular signaling occurs within cells, responding to extracellular and intracellular stimuli.
Types of Signaling
- Direct Signaling: Direct cell-to-cell signaling through gap junctions, allowing electrical signal transduction and the transfer of ions or small molecules between cells.
-
Chemical Signaling: Signaling by secreted molecules, including:
- Endocrine Signaling: Hormones produced by endocrine glands, traveling through the bloodstream to distant cells, and received by surface or intracellular receptors.
- Paracrine Signaling: Signals similar to hormones, but not entering the bloodstream, and traveling to nearby cells, with the gradient of signal molecules determining the outcome.
- Autocrine Signaling: Signal molecules secreted by the target cell, such as prostaglandins, with the key difference being that the target cell is also the signaling cell.
Gap Junctions
- Allow direct communication between cells through the transfer of ions or small molecules.
- Composed of connexons, which are transmembrane proteins forming a 3 nm thin hydrophilic channel.
- Facilitate direct communication between cells, enabling the transfer of signaling molecules such as ATP, cAMP, IP3, Na+, K+, and Ca2+.
Second Messengers
- Produced in response to signal binding, causing a cellular response.
- Some signals can cross the membrane and bind to receptors in the cytoplasm.
Coagulation Cascade
- A series of enzyme reactions that lead to the formation of a blood clot, involving plasma proteinase cascades
- Types of cascades: Coagulation (forms fibrin), Fibrinolytic (degrades fibrin), Complement (inflammation), Kinin (inflammation)
Blood Functions
- Delivers plasma-borne substances to tissues
- Removes waste, delivers oxygen, and carries heat
- Delivers defensive leukocytes to tissues
- Aids hemostasis in case of blood vessel injury
- Coagulation and Fibrinolytic cascades ensure balance between clotting and bleeding
Hemostasis
- Requires: Reflex Vasoconstriction, Initial Platelet plug, Coagulation cascade, and Fibrin stabilisation
- Platelets:
- Activated by contact with extravascular material
- Adhesion to surface, activation, degranulation, and aggregation
- Secondary haemostasis:
- Exposure of tissue factor (TF) binds Factor VII, activating Extrinsic Coagulation Cascade
- Thrombin converts soluble fibrinogen to insoluble fibrin
- Thrombin recruits further platelets, forming a solid permanent plug
Counter-Regulatory Mechanisms
- Fibrinolytic cascade: Tissue plasminogen activator (t-PA) generates plasmin, degrading fibrin
- Thrombomodulin interferes with the coagulation cascade
- Mechanisms restrict inappropriate extension of the haemostatic plug beyond the site of injury
Plasma Proteins
- Albumin: the major protein (50% of all plasma protein, 4% w/v), transport protein
- Other proteins: Clotting Cascade, Fibrinolytic Cascade, Kinin cascade, Complement cascade, Antibodies/anti-microbials, Hormones, Inflammatory mediators
Proteinase Cascades
- Involved in proteolysis, breakdown of proteins into smaller polypeptides
- Inactive proteinase substrates are activated by proteinase activity, leading to amplification of an initially small signal
Normal Haemostasis
-
- Transient arteriolar vasoconstriction: Reflex neurogenic stimulation, Endothelin release
-
- Primary haemostasis: Platelet adhesion and activation, platelet flattening, release of secretary granules, recruitment of additional platelets
Action Potential
- Depolarization of the cell membrane occurs when the membrane potential becomes less negative and more positive (+30mV)
- This is due to the opening of voltage-gated Na+ channels, allowing an influx of Na+ ions
- The membrane is approximately 600 times more permeable to Na+ ions
- Local depolarization of the cell membrane causes the spread of depolarization down the axon, but it decays with distance
Voltage-Gated Na+ Channels
- These channels are ion-selective, only allowing Na+ ions to pass through
- They are controlled by a voltage sensor that responds to the level of the membrane potential
- Normally, these channels are closed, but they open when prompted by a gating agent (voltage above the threshold)
Action Potential Phases
- Phase I: Depolarization
- Phase II: Repolarization (inactivation of voltage-gated Na+ channels, opening of voltage-gated K+ channels, and K+ efflux)
- Phase III: Hyperpolarization and return to Resting Membrane Potential (RMP)
Propagation of Action Potential
- Sequential opening, inactivation, and closing of Na+ and K+ voltage-gated channels cause depolarization and repolarization of the cell membrane
- After an action potential, there is a refractory period when the membrane is hyperpolarized and not as excitable
Speed of Action Potential Propagation
- Axon resistance affects the speed of propagation (larger diameter = less resistance, myelin provides additional insulation)
- Action potentials are only produced in the exposed spaces of Ranvier's nodes
- Current spreads under myelin, but unmyelinated nerve has slower conduction due to current leak
Synaptic Signaling
- A special case of paracrine signaling that involves a special structure (synapse)
- Only occurs between cells with a synapse (communication between neurons or between neuron and effector cells)
Neurotransmission
- Biological active chemicals (neurotransmitters) that transmit signals from a neuron to another neuron or target cell across a synapse
- Excitatory neurotransmitters (e.g., Acetylcholine, Noradrenaline, Glutamate) cause influx of Na+ and depolarization
- Inhibitory neurotransmitters (e.g., GABA, Glycine) cause influx of Cl- and hyperpolarization
Importance of Action Potential and Neurotransmitters
- Understanding action potential and neurotransmitters is crucial for health professionals in managing pain and other conditions
Pain Management
- tooth pain is transmitted through Aδ fibers (myelinated, fast, sharp pain) and C fibers (unmyelinated, slow, burning sensation)
Local Anaesthesia
- Local anaesthetic (e.g., lignocaine) reversibly prevents transmission of the nerve impulse in the region to which it is applied
- Lignocaine binds to voltage-gated Na+ channels in the peripheral nerve cell membrane and blocks the influx of Na+
Recap
- Action potential is a brief reversal of electric polarization of the cell membrane
- Controlled by movement of ions across the cell membrane
- Important for communication between cells
Hyaluronic Acid
- Formed at the cell surface by an enzyme complex
- Not sulphated
- Extremely long chains
- Acts as a scaffold, binding many proteoglycans
- Known as the 'goo' molecule
- A major component of the Extracellular Matrix (ECM), especially abundant in synovial fluid
Heparan Sulphate
- Components manufactured in the Golgi
- Similar to hyaluronic acid, except highly sulphated
- Regulates a wide range of biological activities, including angiogenesis, blood coagulation, and cellular signalling
Proteoglycans
- Consist of a protein core with attached Glycosaminoglycans (GAGs), excluding hyaluronic acid
- Can form non-covalent complexes with hyaluronic acid
- Known as the 'filler' of ECM space
- The major biological function of proteoglycans derives from the physicochemical characteristics of GAGs
Collagen
- Synthesized intracellularly and matured extracellularly
- A major component of the ECM
Elastin
- Similar to collagen
- Hydrophobic uncoiling domains, giving it a 'rubber band' property
Glycosaminoglycans (GAGs)
- Also known as mucopolysaccharides
- Long, unbranched polysaccharides
- All repeating disaccharide units, consisting of an amino sugar and a uronic acid
- Strongly negatively charged, often sulphated and carboxyl groups
- Attract and trap water by strong charge and trapping cations, providing hydration and swelling pressure to withstand compression forces
ECM turnover
- Permits remodeling and adaptation to function
- Synthesis balanced by degradation
- Degradation by enzymes, such as hyaluronidase, metalloproteinases, and serine proteinases
Connective Tissue
- Joins tissues together
- Usually has blood vessels
- Cells are separated from each other
- Extracellular matrix (ECM) consists of collagen, elastin, glycosaminoglycans, and hyaluronic acid
- Supports the organs and other special tissues
- Fills in spaces
- Supports the epithelium (lamina propria)
Types of Connective Tissue
- Loose collagenous connective tissue
- Dense collagenous connective tissue
- Elastic tissue
- Bone
- Cartilage (no blood vessels)
- Adipose tissue (fat)
- Blood
Loose Connective Tissue
- Has blood vessels, elastin fibers, and fibroblasts
- Example: small intestinal mesentery
Dense Connective Tissue
- Tendon is a good example
- Has neatly arranged collagen fibers
- Macroscopically, tendons are white/opaque because they have very few blood vessels
- Very similar to scar tissue in appearance and structure
Tendons
- Join muscles and bones together
- Sometimes form between tissue masses and organs
- Lots of collagen fibers, making them hard and rope-like
Adipose Tissue
- Special connective tissue
- Triglyceride/H2O store
- Structural, especially in hands, soles, orbit, and resist starvation
- Body contour, influencing sexual morphology
Bone
- Highly vascular
- Calcified collagen
- Internal structure optimized to resist forces (Wolf's Law)
- Soft tissue (marrow) in spaces
Bone Remodeling
- Always a surface process
- Key cells involved: osteoblasts, osteocytes, and osteoclasts
Epithelial Tissues
- Epithelial cells are tightly bound together and rest on a basement membrane with distinct polarity.
- They have no vascular supply, and nutrients are delivered by diffusion and mitosis.
Characteristics of Epithelial Cells
- They renew continuously by mitosis.
- They have structural and functional polarity.
- They are avascular, meaning they have no direct blood supply.
Roles of Epithelia
- Protection (skin)
- Absorption (small and large intestine)
- Transport of material at the surface (mediated by cilia)
- Secretion (glands)
- Excretion (tubules of the kidneys)
- Gas exchange (lung alveolus)
Types of Epithelia
- Squamous (meaning scale-like)
- Cuboidal
- Columnar
Epithelial Tissue Organization
- Simple epithelial tissue
- Stratified epithelial tissue
- Pseudo-stratified epithelial tissue (looks stratified but all cells are in contact with the basement membrane)
Basement Membrane
- A specialized extracellular matrix (ECM) sheet
- Composed of intertwining collagen fibers
Cell Junctions
- Desmosomes: keratin-binding, permeable to H2O2 and ions, and able to resist mechanical stress
- Hemidesmosomes: anchor epithelial cells to the basement membrane
- Examples of desmosomes and hemidesmosomes can be found in skin, intestines, and respiratory tract
Clinical Relevance
- Epithelial transition zone is vulnerable to HPV invasion and subsequent immortalization (cancer) of cervical epithelial cells.
Central Dogma
- The central dogma describes the flow of genetic information during cell growth and replication: DNA → RNA → Protein
- Information doesn't flow backward
- Proteins and some RNA are considered "gene products"
Transcription
- Transcription is the DNA-directed synthesis of RNA
- Same language is used between DNA and RNA
- DNA is long, while RNA is short and contains only a few genes
- In eukaryotes, each gene is transcribed to give a separate mRNA that encodes only a single protein
- In prokaryotes, an mRNA molecule may carry information from a single gene or from several genes next to each other on the chromosome
Transcription Process
- Unwinding of DNA double helix
- Template strand is used
- Complementary base pairing occurs
- RNA polymerase forms RNA
- Uracil is the base that would be in the RNA sequence that wouldn't be in the DNA sequence being copied
Types of RNA
- mRNA: carries gene information
- tRNA: involved in protein synthesis
- rRNA: makes up ribosomes
- MicroRNA: regulates gene expression
Translation
- Translation is the synthesis of proteins from RNA
- mRNA nucleotide sequence is translated into amino acids, which is a different language
- The genetic code is a dictionary that links a sequence of RNA to an amino acid
The Genetic Code
- Problem: 4 different RNA bases, but 20 different amino acids
- Solution: the genetic code, which links a sequence of RNA to an amino acid
- Codon: 3 RNA bases that code for 1 amino acid
Mutations
- Silent mutations: codon containing a changed RNA base, but codes for the same amino acid
- Missense mutations: codon contains a changed RNA base, producing a different amino acid
The Genome
- The genome is the complete set of information in an organism's DNA
- Carries information for gene expression, protein synthesis, and more
- Huge amount of information: 3.0 x 10^9 base pairs of DNA, 20,000-25,000 genes
- Genes account for 2% of the genome, while 98% is non-coding DNA
Packaging of the Genome
- Problem: 2 meters of DNA per cell, but the cell nucleus is only 6μm
- Solution: DNA is wrapped around histone proteins to form chromatin, which is then wound up to form chromosomes
- Chromosomes have a centromere (center) and telomere (ends)
Karyotype
- A karyotype is the complete set of chromosomes in an organism
Human Embryo Development
- At 4 weeks, the human embryo has pharyngeal arches, occipital somites, cervical somites, forelimb bud, heart, and umbilicus.
- Somites are blocks of mesoderm that form muscle and bone.
Pharyngeal Arch Formation
- Pharyngeal arches form at day 23, with the first arch forming on day 22.
- The pharyngeal arches are formed from the pharyngeal/visceral/branchial region.
Development of Pharyngeal Arches
- The first pharyngeal arch appears on day 22, with the second and third arches appearing on day 24, and the fourth and sixth arches appearing on day 29.
- The contents of the pharyngeal arches include muscle, cartilage, cranial nerves, and blood vessels.
Development of the Pharynx
- Pharyngeal pouches form on the endodermal side between the arches, with pharyngeal grooves (or clefts) forming from the lateral ectodermal surface of the neck region to separate the arches.
Muscle Development
- Muscle cells from the superior somites invade the pharyngeal arches.
- The muscles derived from the pharyngeal arches include:
- First arch: masticatory muscles, mylohyoid, anterior belly of digastric, tensor tympani, and TVP.
- Second arch: facial expression, posterior belly of digastric, stylohyoid, and stapedius.
- Third arch: stylopharyngeus.
- Fourth and sixth arches: intrinsic laryngeal and pharyngeal muscles.
Cartilage and Bone Development
- Neural crest cells from the developing brain form cartilage and cranial nerves in the pharyngeal arches.
- The cartilage and bone derived from the pharyngeal arches include:
- First arch: Meckel's cartilage (mandible), Palatopterygoquadrate bar (part of sphenoid), malleus, and incus.
- Second arch: stapes, part of hyoid, and temporal bones.
- Third arch: part of hyoid.
- Fourth and sixth arches: larynx cartilage.
Cranial Nerve Development
- Neural crest cells from the developing brain form cranial nerves in the pharyngeal arches.
- The cranial nerves derived from the pharyngeal arches include:
- First arch: Trigeminal (V2, V3).
- Second arch: Facial nerve (VII).
- Third arch: Glossopharyngeal (IX).
- Fourth and sixth arches: Vagus (X).
Blood Vessel Development
- The blood vessels derived from the pharyngeal arches include:
- First arch: Maxillary artery and external carotid artery.
- Second arch: Internal carotid artery.
- Fourth and sixth arches: Arch of the aorta.
Development of the Face
- The development of the face involves the formation of the frontonasal process, maxillary process, and mandibular process.
- The face develops from the fusion of the frontonasal process, maxillary process, and mandibular process.
Development of the Hard Palate
- The development of the hard palate involves the formation of the primary palate and the secondary palate.
- The primary palate is formed from the fusion of the medial nasal processes, while the secondary palate is formed from the fusion of the maxillary process and the palatal shelves.
- The hard palate is formed from the ossification of the maxilla and the mid-palatal suture.
Malformations of the Face and Palate
- Cleft lip and palate can occur due to the failure of fusion of the maxillary process and the medial nasal process.
- Cleft palate can occur due to the failure of fusion of the palatal shelves.
- Orofacial clefts occur in 1 in 700 births, with cleft lip with cleft palate occurring in 1 in 1600 births, and cleft palate without cleft lip occurring in 1 in 2800 births.
- Cleft palate is more common in females than males, with a ratio of 2:1.
- Cleft palate often occurs with other defects in one-third of cases.
Stages of Tooth Development
- There are six stages of tooth development: initiation, bud, cap, bell, root formation, and eruption
- Each stage is characterized by specific changes in the structure and formation of the tooth
Initiation Stage
- The initiation stage is the first stage of tooth development
- It is characterized by the formation of the primary epithelial band and the dental lamina
Bud Stage
- The bud stage is the second stage of tooth development
- It is characterized by the formation of the bud and the condensation of ectomesenchyme
Cap Stage
- The cap stage is the third stage of tooth development
- It is characterized by the formation of the cap and the differentiation of the inner enamel epithelium
Bell Stage
- The bell stage is the fourth stage of tooth development
- It is divided into early and late bell stages
- The early bell stage is characterized by the formation of the papilla and the differentiation of the inner enamel epithelium
- The late bell stage is characterized by the formation of the cervical loop and the differentiation of the outer enamel epithelium
Root Formation Stage
- The root formation stage is the fifth stage of tooth development
- It is characterized by the formation of the root sheath and the differentiation of odontoblasts
Tooth Structure
- A tooth is composed of enamel, dentine, and cementum
- The enamel is the outermost layer of the tooth
- The dentine is the layer beneath the enamel
- The cementum is the layer that covers the root of the tooth
Enamel Formation
- Enamel is formed by the differentiation of ameloblasts
- The ameloblasts produce enamel matrix proteins that are deposited on the dentine
- The enamel matrix proteins are then mineralized to form the enamel
Dentine Formation
- Dentine is formed by the differentiation of odontoblasts
- The odontoblasts produce dentine matrix proteins that are deposited on the pulp
- The dentine matrix proteins are then mineralized to form the dentine
Cementum Formation
- Cementum is formed by the differentiation of cementoblasts
- The cementoblasts produce cementum matrix proteins that are deposited on the root of the tooth
- The cementum matrix proteins are then mineralized to form the cementum
What are Micro-organisms?
- Micro-organisms are defined as organisms too small to be seen by the unaided eye, less than 1mm in diameter.
- They are important because they make life possible, produce foods, and cause disease.
Classes of Microbes
- Cellular microorganisms:
- Bacteria (e.g. Escherichia coli, Porphymonas gingivalis)
- Archea (e.g. Methanogens)
- Fungi (e.g. Yeasts)
- Protists (e.g. Algae, Protozoa, Slime molds)
- Acellular microorganisms:
- Viruses (e.g. HIV, Herpes, COVID)
- Viroids (RNA, plant diseases)
- Virusoids (nucleic acids, animal diseases)
- Prions (infectious proteins, e.g. scrapie and mad cow disease)
Characteristics of Micro-organisms
- Bacteria:
- Prokaryotes
- Single-celled
- Cell walls contain peptidoglycan
- Ubiquitous in environment and human microbiome
- Diseases: caries, periodontal disease, skin infections, food poisoning
- Fungi:
- Eukaryotes
- Diverse group
- Unicellular (e.g. yeasts) or multicellular (e.g. molds and mushrooms)
- Role in oral thrush (e.g. Candida albicans)
- Protists:
- Algae: produce 50% of the world's oxygen
- Protozoa: motile, hunter-gatherers
- Slime molds
- Water molds
- Human disease: e.g. malaria
Importance of Micro-organisms
- Microbes are involved in human disease
- Koch's postulates: a set of criteria to establish a causal link between a microbe and a disease
- Reservoirs of microbes: humans, animals, soil, water
- Mechanisms of transmission: direct contact, vectors, airborne, waterborne
Summary
- Microbes are diverse and divided into cellular and acellular groups
- Microbes are involved in many human diseases, particularly oral infections
- Understanding micro-organisms is important for human health and disease prevention
Bacterial Morphology and Nomenclature
- Bacteria can be classified based on their morphology (shape and arrangement) and nomenclature (naming convention)
Morphology
- Bacterial shapes:
- Cocci: round or spherical
- Bacilli: rod-shaped
- Spirochaetes: spiral-shaped
- Other shapes: filamentous, curved, pleomorphic
- Bacterial arrangements:
- Clumps: e.g., Staphylococci
- Chains: e.g., Streptococci
- Twos/Diplo: e.g., Diplococci
- Fours/Tetrads: e.g., Micrococci
- Eights/Cubic: e.g., Sarcina sp. mutans
Respiration
- Aerobes: require oxygen (O2)
- Anaerobes: require carbon dioxide (CO2)
Classification of Bacteria
- Historical criteria:
- Staining (Gram-positive or Gram-negative)
- Shape (rods, cocci)
- Respiration (aerobes or anaerobes)
- Modern criteria:
- Genomic similarity (DNA sequence similarity to reference sequences)
Nomenclature
- Latin name: e.g., Escherichia coli K1
- Genus species strain: e.g., Escherichia coli K1
- Strain: descendants of a single cell with a distinct characteristic(s)
- Species: a collection of strains that share many stable properties and differ significantly from other groups of strains
- Genus: a group of species exhibiting similar characteristics
- Species name: written in italics, with genus name capitalized and species name in lowercase
Phylogenetic Tree
- Based on genetic data
- Tips represent nucleotide sequences
- Origin: last common ancestor
- Branching points: represent a divergence event
- Distance between tips: reflects the number of genetic changes
Bacterial Growth Curve
- The growth curve consists of four phases: Lag, Exponential, Stationary, and Death.
- Lag phase: adjustment period, bacteria adapting to new environment, replicating chromosomes to build new proteins/enzymes.
- Exponential phase: cells growing and dividing, maximal growth, continues until nutrients are exhausted or inhibitory molecules accumulate.
- Stationary phase: cell numbers stop increasing, DNA replication is arrested, cells produce new proteins to enhance survival during starvation.
- Death phase: cells stop growing, even if supplied with new medium.
Bacterial Growth in Oral Environment
- Lag phase: immediately after a meal, adjusting to new influx of nutrients.
- Exponential phase: after meal, post adjustment, cells dividing maximally.
- Stationary phase: period of fasting in between meals, nutrients limited, bacteria susceptible to antimicrobials.
- Death phase: variable between bacteria.
Growing Bacteria in the Lab
- Media consistency: solid, semi-solid, and liquid media support bacterial growth.
- Solid media: allows for isolation of single colonies.
- Semi-solid media: for microaerophilic bacteria.
- Liquid media: allows for uniformed growth until either nutrient limitation or build-up of inhibitors.
Bacteria Quantification
- Methods: cell counting under a microscope, serial dilution and plating on agar, qPCR.
- qPCR: relative quantification or absolute quantification.
Optical Density
- Measuring optical density at wavelength 600 nm is typically used to interrogate growth dynamics in the lab.
Conditions Affecting Bacterial Growth
- Temperature: most bacteria grow optimally at 37°C, but can vary between 0°C and 121°C.
- pH: most bacteria grow optimally between pH 7-8, but can vary between pH 0 and 11.
- Oxygen: strict aerobes require oxygen, facultative aerobes prefer oxygen, facultative anaerobes prefer no oxygen, and strict anaerobes cannot grow in oxygen.
Culture Media
- Defined media: exact composition known.
- Complex media: extracts from plants or animal, exact composition unknown.
- Additives can be incorporated to enrich or inhibit certain bacteria.
Gut Microbiota
- The stomach has a highly acidic environment, resulting in few viable bacteria.
- The small intestine is acidic with bile juices, which also limits the presence of viable bacteria.
- The large intestine has a huge diversity of bacteria, with 10^12 cells per gram of stool.
- Symbiotic relationships between gut microbiota and the host:
- Produce biotin and vitamin K.
- Prevent pathogens from colonizing.
- Aid in the absorption of nutrients.
Oral Microbiota
- The mouth is colonized soon after birth.
- After tooth eruption, anaerobes such as Porphymonas, Prevotella, and Fusobacterium species increase.
- Symbiotic relationships between oral microbiota and the host:
- Alter taste perception.
- Distinguish between super-tasters and non-tasters.
- Vary in tongue microbiota.
Changes to the Oral Microbiota
- The oral microbiome can modulate nitric oxide homeostasis and blood pressure in humans.
Homeostasis and Dysbiosis
- Dysbiosis is an example of changes to the microbiota, such as in obesity.
- Germ-free mice versus conventional mice on the same diet.
- Germ-free mice can eat more and gain less weight than conventional mice.
- Microbiota affects caloric absorption.
- Dysbiosis can cause dental conditions, including:
- Dental caries.
- Periodontal disease.
- Oral cancer.
Microbe-Host Interaction
- Humans are holobionts, consisting of a host and microbiome.
- Microbes can be beneficial or cause harm.
- The microbiome across the human body is diverse and can be in flux.
Host-Microbe Interactions
- Infection/colonization: the acquisition of microorganisms by the host.
- Commensalism: a state of infection that results in no damage to the host.
- Symbiosis/mutualism: a state of infection where both the host and microbe benefit.
Humans as Holobionts
- A holobiont is a host and its microbiome.
- The human microbiome consists of all microbes that share our body space.
- Humans carry 10^14 microbial cells and 10^13 human cells.
- Humans need their microbiome for beneficial tasks and protection from foreign substances and pathogens.
Microbiome - Commensals
- Commensals are 'normal' microbes present on the skin and in the oral, respiratory, and gastrointestinal tracts.
- They protect the host against pathogens and provide nutrients.
- Commensals are acquired in the first year of life.
Microbiome Composition
- The microbiome has a huge diversity in composition, including bacteria, fungi, and viruses.
- Some members are culturable, while most cannot be cultured.
- Culture-independent methods are used to study the microbiome.
16S Ribosomal RNA Sequencing
- 16S rRNA is a subunit of the ribosome.
- It has a slow rate of evolution and is highly conserved between bacteria and archaea.
- It has hypervariable regions that can be used to study diversity.
Shotgun Metagenomics
- Shotgun metagenomics involves sequencing every nucleic acid within a given sample, including DNA and RNA.
- It can be used to study bacteria, viruses, fungi, and even host DNA.
- It allows for extended characterization of the community, including subtyping, AMR genes, and virulence genes.
Metagenomics Can Be Used for Insights into Population Dynamics
- Metagenomics can provide insights into population dynamics.
Host Microbiome Varies with Body Site
- The microbiome varies across different body sites, including the skin, gut, and oral cavity.
Skin Microbiota
- The skin environment is slightly acidic, with high salt, low water content, and inhibitory substances.
- Bacteria are present on superficial skin (dead cells) and sweat glands.
- Bacteria partially degrade skin oil to volatile fatty acids, contributing to body odor.
Respiratory Microbiota
- The respiratory microbiota has a specific composition and function.
Gut Microbiota
- The stomach has a highly acidic environment, resulting in few viable bacteria.
- The small intestine is acidic with bile juices, which also limits the presence of viable bacteria.
- The large intestine has a huge diversity of bacteria, with 10^12 cells per gram of stool.
- Symbiotic relationships between gut microbiota and the host:
- Produce biotin and vitamin K.
- Prevent pathogens from colonizing.
- Aid in the absorption of nutrients.
Oral Microbiota
- The mouth is colonized soon after birth.
- After tooth eruption, anaerobes such as Porphymonas, Prevotella, and Fusobacterium species increase.
- Symbiotic relationships between oral microbiota and the host:
- Alter taste perception.
- Distinguish between super-tasters and non-tasters.
- Vary in tongue microbiota.
Changes to the Oral Microbiota
- The oral microbiome can modulate nitric oxide homeostasis and blood pressure in humans.
Homeostasis and Dysbiosis
- Dysbiosis is an example of changes to the microbiota, such as in obesity.
- Germ-free mice versus conventional mice on the same diet.
- Germ-free mice can eat more and gain less weight than conventional mice.
- Microbiota affects caloric absorption.
- Dysbiosis can cause dental conditions, including:
- Dental caries.
- Periodontal disease.
- Oral cancer.
Microbe-Host Interaction
- Humans are holobionts, consisting of a host and microbiome.
- Microbes can be beneficial or cause harm.
- The microbiome across the human body is diverse and can be in flux.
Host-Microbe Interactions
- Infection/colonization: the acquisition of microorganisms by the host.
- Commensalism: a state of infection that results in no damage to the host.
- Symbiosis/mutualism: a state of infection where both the host and microbe benefit.
Humans as Holobionts
- A holobiont is a host and its microbiome.
- The human microbiome consists of all microbes that share our body space.
- Humans carry 10^14 microbial cells and 10^13 human cells.
- Humans need their microbiome for beneficial tasks and protection from foreign substances and pathogens.
Microbiome - Commensals
- Commensals are 'normal' microbes present on the skin and in the oral, respiratory, and gastrointestinal tracts.
- They protect the host against pathogens and provide nutrients.
- Commensals are acquired in the first year of life.
Microbiome Composition
- The microbiome has a huge diversity in composition, including bacteria, fungi, and viruses.
- Some members are culturable, while most cannot be cultured.
- Culture-independent methods are used to study the microbiome.
16S Ribosomal RNA Sequencing
- 16S rRNA is a subunit of the ribosome.
- It has a slow rate of evolution and is highly conserved between bacteria and archaea.
- It has hypervariable regions that can be used to study diversity.
Shotgun Metagenomics
- Shotgun metagenomics involves sequencing every nucleic acid within a given sample, including DNA and RNA.
- It can be used to study bacteria, viruses, fungi, and even host DNA.
- It allows for extended characterization of the community, including subtyping, AMR genes, and virulence genes.
Metagenomics Can Be Used for Insights into Population Dynamics
- Metagenomics can provide insights into population dynamics.
Host Microbiome Varies with Body Site
- The microbiome varies across different body sites, including the skin, gut, and oral cavity.
Skin Microbiota
- The skin environment is slightly acidic, with high salt, low water content, and inhibitory substances.
- Bacteria are present on superficial skin (dead cells) and sweat glands.
- Bacteria partially degrade skin oil to volatile fatty acids, contributing to body odor.
Respiratory Microbiota
- The respiratory microbiota has a specific composition and function.
Disadvantages of Living in a Biofilm
- Slow diffusion of nutrients and buildup of by-products due to biofilm structure
- Difficulty in removing substances, leading to buildup of heavy metals
- Bacteriocins, protein toxins that target similar bacteria, produced by S. salivarius to reduce URT infections
Oral Microbiology
- 6 months of childhood: tooth emergence and establishment of solid foods, leading to increased diversity of oral microbiome
- Bacterial taxa emerging during this period include Fusobacterium, Lactobacillus, Neisseria, Gemella, and Haemophilus
- Streptococcus species dominate the infant oral microbiome in early childhood, with a narrow diversity
- Impact of delivery mode and early feeding on oral microbiome development
- Type of milk consumed influences early diversity, with breast-fed infants having higher abundances of Streptococcus and Veillonella species
Plaque Development
- Mutans exchange DNA to enable bacteria to tolerate acidic conditions
- Advantages and disadvantages of life within a biofilm
Learning Objectives
- Know stages of microbial colonization of the oral cavity
- Understand factors influencing microbial colonization of the oral cavity
- Know factors causing changes in oral microbial composition over time
- Know stages of plaque development
- Know advantages and disadvantages of life within a biofilm
Leukocytes (White Blood Cells)
- Neutrophilic PMN (most common WBC):
- Kills bacteria
- Makes pus
- Involved in immunity against parasitic infections, especially in the intestine
- Plays a role in allergies and asthma
- Monocytic PMN:
- Kills bacteria
- Eats debris
- Attacks intracellular pathogens
- Has a wide role in immunity
- Can become macrophages
- Lymphocytes (second most common type of WBC):
- Includes T, B, and NK cells
- Involved in specific immunity
- Provides immunity against viruses
- Involved in tumor protection
- Eosinophils (rarest variety of WBC in blood):
- Can become mast cells
- Contributes to allergy
Chemotaxis
- Directional movement of neutrophils towards bacteria
- Triggered by low molecular weight products released by bacteria, such as fMLP and peptidoglycan
- Neutrophils have surface receptors that detect these products
Opsonisation
- Coating of microorganisms by complement system to facilitate phagocytosis
- Recognized by special receptors on phagocytic cells
Phagocytosis
- Capture and digestion of foreign particles by phagocytic cells
- Chemokines attract macrophages and neutrophils to infected tissues
- Opsonins attach to microbes to increase phagocyte adhesion
Killing Mechanisms
- Oxygen-independent pathway: uses lysosomal enzymes (collagenase, gelatinase, phospholipases, or serine proteases)
- Oxygen-dependent pathway: uses reactive oxygen and nitrogen species (RONS)
Innate Immune System
- Cells:
- Antigen-presenting cells (APCs): dendritic cells, macrophages, B cells
- Phagocytic cells: neutrophils, macrophages
- Pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs)
- Effects of activating TLRs:
- Cytokine production (IL-1, TNF) leading to fever and inflammation
- Chemokine production leading to cell recruitment
- Activation of bacterial killing mechanisms
- Activation of dendritic cells
Acquired Immunity
- Has a memory, providing improved protection against future infections
- Basis for immunity against re-infection and immunization
Cells of the Immune System
- Dendritic cells originate from bone marrow, with myeloid/monoblast origins
- Can be tissue-derived (conventional DC) or blood-derived
- Functions: antigen trap, antigen processing, migration, cytokine production (e.g., IL-12)
- Expresses Class II MHC and presents antigens to T-cells
Antigen-Presenting Cells (APCs)
- Sedentary in epithelium/dermis, migrate to draining lymph node, and change phenotype
- Functions: antigen processing, antigen presentation (non-phagocytic)
- Examples: dendritic cells, macrophages, B cells, Langerhans cells
Antigen Presentation to T-Cells - MHC
- MHC class I: expressed on all nucleated cells, present self-antigens
- MHC class II: expressed on professional APCs (dendritic cells, macrophages, B cells, Langerhans cells), present foreign antigens
- Each MHC displays one peptide-MHC complex at a time, with high expression levels increasing the propensity to activate T-cells
MHC Checkpoints for Activation
- MHC-TCR engagement requires co-stimulation (CD28-CD80/CD86)
- IL-2 is released by T cells, promoting proliferation
- 'Brake pads' (CTLA-4) limit expansion after activation
- 3 signals for T-cell activation: TCR-MHC engagement, CD4/8-MHC binding, CD28-CD80/86 binding
Adaptive (Specific) Immunity - Characteristics
- Specificity: recognizing pathogen epitopes
- Memory: accelerated and larger response upon re-exposure
- Self-limitation: mass apoptosis of lymphocytes in the absence of antigen presentation
Antigen Recognition - B Cells and Activation
- T-dependent antigens (e.g., soluble proteins) require T-cell 'help' (CD40, cytokines)
- T-independent antigens (e.g., lipids, polysaccharides) do not require T-cell help
- B1 cells produce 'natural antibody' (IgM only)
- Each B-cell has a unique specificity, with 10 billion possible combinations
Course Overview
- The course covers head and neck anatomy for oral health therapists
- Aim is to provide students with an understanding of the anatomy of the head and neck
Learning Outcomes
- Perform extra- and intra-oral examinations
- Understand and assess oral health condition, and diagnose oral health diseases
- Give local anaesthesia
- Extract teeth
- Recognise variations of normal anatomy and pathology
Anatomical Knowledge
- Identify the major landmarks of the orofacial region
- Identify the bones of the skull
- Identify the ‘muscles of facial expression’, muscles of the neck, ‘muscles of mastication’ and muscles of the tongue
- Describe the blood circulation, lymph nodes and glands of the head and neck
- Describe the basic nervous system biology
- Describe the innervation of the face, head and neck, including the teeth
- Identify the anatomical landmarks of the oral cavity relevant to local anaesthesia
- Identify and describe the components of the temporomandibular joint (jaw joint), (TMJ)
Course Outline - Semester 1
- Introduction to course and anatomical terminology
- Oral Cavity
- Skull (osteology): cranial bones and vertebrae
- Skull (osteology): facial bones
- Muscles: facial expression
- Muscles: mastication, tongue and neck
Course Outline - Semester 2
- Circulation
- Nervous system and cranial nerves
- Trigeminal nerve
- Salivary glands
- Lymph nodes
- Temporomandibular joint
Resources
- Lectures
- Tutorials
- Online material: Glossary, Online Wilson Museum, Acland anatomy videos, Thieme Atlas, Electronic textbooks
Recommended Textbooks
- Introductory Textbooks: Fehrenbach and Herring, 2007, Illustrated anatomy of the head and neck; Phinney and Halstead, 2011, Dental assisting coloring book
- Advanced Textbooks: Anatomy: A Photographic Atlas (9th Edition)
Lecture 1: Introduction to Head & Neck Anatomy
- Introduction to the anatomy course
- Anatomical Terminology: Planes, Laterality, Movement
Movement Terminology
- Lateral Flexion: movement of head towards shoulder
- Rotation: turning the head around to a particular side away from midline
- Elevation & Depression: moving a body part superiorly or inferiorly
- Protraction & Retraction: jutting jaw out and bringing it back
- Abduction: moving away from midline
- Adduction: moving towards midline
Soft Palate
- Contains muscles, aponeuroses, fat, and glands
- Muscles and aponeuroses are part of the palatine muscles
- Fat and glands are present in the soft palate
Palatine Aponeurosis
- Thin, firm, fibrous sheet formed by the expanded tendon of the tensor palati muscle
- Provides support to the other palatine muscles that attach to it and gives strength to the soft palate
Muscles of Palate
- There are five paired palatal muscles:
- Levator palati: lifts the palate up and back
- Tensor palati: tightens the palate and pulls the auditory tube open
- Palatoglossus: forms the posterior pillar of the fauces
- Palatopharyngeus: forms the posterior pillar of the fauces
- Exhibits first signs of inflammation through redness, bleeding, or swelling
Gingiva (Gums)
- Gingiva proper: covers the alveolar processes of the maxilla and mandible and finishes at the neck of each tooth
- Two types of gingiva:
- Free gingiva: forms a collar around the tooth and is not attached to bone (normally 1-3mm depth)
- Attached gingiva: adjacent to free gingiva and is firmly attached to bone structure (can range 3-12mm in height)
Tongue
- Mobile muscular organ
- Two parts: oral (moveable part) and pharyngeal (non-moveable part)
- Covered in mucous membrane
- Functions:
- Speaking
- Mastication
- Taste
- Swallowing
Tongue Structure
- Dorsal (upper) surface:
- Oral (anterior 2/3) and pharyngeal (posterior 1/3) parts are divided by the palatoglossal arch and sulcus terminalis
- Foramen caecum: remnant of the embryological duct associated with the thyroid gland
- Ventral (inferior) surface:
- Body: oral part of the tongue
- Apex: tip of the tongue
- Root: connected to the hyoid bone via the hyoglossus and genioglossus muscles
Oral Tongue – Dorsal
- Lingual papilla:
- Fungiform (white circle)
- Filiform (fur)
- Vallate (7-12, mushroom)
- Taste buds associated with all except filiform papillae
Oral Tongue – Ventral
- Frenulum
- Deep lingual veins
- Fimbriated folds (slight fold of mucous membrane)
- Sublingual folds with openings and sublingual papilla (prominence of mucous membrane that overlies the sublingual gland, has openings for sublingual and submandibular glands)
Extrinsic Muscles of Tongue (Position the tongue)
- Genioglossus: upper genial tubercle to hyoid bone and base of tongue, protrusion/deviation
- Hyoglossus: hyoid bone to side of tongue, depresses side of tongue (sucking, retraction)
- Styloglossus: styloid process to side of tongue, lifts tongue up and back
- Palatoglossus: palatal aponeurosis to side of tongue, tongue up
Intrinsic Muscles of Tongue (Shape the tongue)
- Superior longitudinal muscles: elevate, assist in retraction
- Transverse and vertical muscles: narrow the tongue, and pull the tongue towards the floor of the mouth
- Inferior longitudinal muscles: deviate the tongue to the side and pull the tip of the tongue downwards, also assists in retraction
Intervertebral Disc and Vertebral Spine
- Intervertebral discs provide cushioning to reduce stress of impact, protect nerves, and allow movement.
- Synovial joints allow for motion of the vertebral spine.
Cranial Fossae
- The internal cranial cavity has three cranial fossae: anterior, middle, and posterior.
- Each fossa has a specific floor and boundaries.
Anterior Cranial Fossa
- Floor: orbital plate of frontal bone and lesser wing of sphenoid bone.
- Features: cribriform plate, crista galli, and olfactory nerve filaments.
Ethmoid Bone
- Features: crista galli, cribriform plate, perpendicular plate, superior and middle nasal conchae, medial wall of orbit, and ethmoidal air cells.
Middle Cranial Fossa
- Floor: body of sphenoid bone medially and greater wing of sphenoid bone laterally.
- Features: hypophyseal fossa, pituitary gland, and posterolateral boundaries.
Sphenoid Bone
- Features: greater and lesser wings, body, hypophyseal fossa, sphenoid sinus, orbital surface, optic canal, superior orbital fissure, and pterygoid plates.
Posterior Cranial Fossa
- Floor: occipital bone and petrous temporal bone.
- Features: clivus and posterior boundaries.
Skull Bones
- The skull consists of 22 bones: 8 cranial bones and 14 facial bones.
- Cranial bones: frontal, temporal, parietal, occipital, ethmoid, and sphenoid.
- Facial bones: maxilla, zygomatic, lacrimal, nasal, inferior nasal conchae, palatine, mandible, and vomer.
Skull Features
- The articulations between the bones are mostly non-moveable sutures, fibrous joints that may ossify with age.
- Exceptions to this are the Temporomandibular Joint (TMJ) and the ossicles of the ear.
- Terminology: body, processes/plates/spines, and eminence.
Facial Bones
- The facial skeleton consists of 14 bones that form the orbit, nasal cavity, oral cavity, and paranasal sinuses.
- The facial bones are frontal, nasal, maxilla, mandible, zygomatic, sphenoid, temporal, parietal, lacrimal, inferior nasal concha, and ethmoid.
Orbit
- The orbit is formed by 7 bones: frontal, ethmoid, sphenoid, zygomatic, lacrimal, maxilla, and palatine.
- The zygomatic bone forms the infraorbital margin and articulates with maxilla, frontal, temporal, and sphenoid bones.
- The lacrimal bone contributes to the medial wall of the orbit and contains the nasolacrimal duct.
Maxilla
- The maxilla is a paired bone that contributes to the orbit, nasal cavity, and oral cavity.
- The maxilla articulates with nasal, lacrimal, zygomatic, ethmoid, vomer, and palatine bones.
- The maxilla has a frontal process, infraorbital groove, maxillary tuberosity, anterior nasal spine, infra-orbital foramen, zygomatic process, and alveolar process with teeth.
Nose and Nasal Cavity
- The external structure of the nose is formed by the nasal bone, frontal process of maxilla, and nasal process of frontal bone.
- The nasal cavity has a floor, roof, and lateral wall formed by 8 bones: nasal, frontal, ethmoid, sphenoid, maxilla, lacrimal, inferior nasal concha, and palatine.
- The nasal septum has a cartilaginous part anteriorly and a bony part posteriorly.
Other Bones
- The mandible is a bone that forms the lower jaw.
- The hyoid bone is not part of the facial skeleton.
- The paranasal sinuses are air-filled cavities within the facial bones.
- The oral cavity is formed by the maxilla, mandible, and palatine bones.
Muscles of Facial Expression
- Muscles of facial expression are skeletal muscles, meaning they are voluntary, striated, and attached to bones, cartilages, ligaments, fascia, organs, skin, or mucous membranes.
Categories of Muscles in the Head and Neck Region
- Muscles in the head and neck region can be categorized into:
- Muscles of facial expression
- Muscles of mastication (chewing and swallowing)
- Muscles of the tongue (swallowing)
- Muscles of the neck (movement of head and neck, speaking)
Muscles of Facial Expression
- All muscles of facial expression are paired except for the orbicularis oris
- Muscles of facial expression generally originate from bone and insert into skin, where short tendons intertwine with collagen of the dermis
Scalp, Forehead, and Eyebrows
- Occipitofrontalis muscle:
- Has two bellies: frontal and occipital, joined by epicranial aponeurosis
- Origins: frontal belly from aponeurosis to skin of eyebrows, occipital belly from superior nuchal line to aponeurosis
- Actions: surprise, frown
- Corrugator supercilli muscle:
- Origin: supraorbital ridges
- Insertion: skin of eyebrow
- Action: frown
- Procerus muscle:
- Origin: nasal bones
- Insertion: skin of eyebrow
- Action: frown
Muscles of the Neck
- Anterior/Lateral muscles of the neck include:
- Suprahyoid muscles: Digastric, Mylohyoid, Stylohyoid, Geniohyoid
- Infrahyoid muscles: Omohyoid, Thyrohyoid, Sternohyoid, Sternothyroid
Posterior Triangle
- Muscles in the floor of the posterior triangle include:
- Splenius capitus muscle
- Levator scapulae muscle
- Scalene muscles (posterior, middle, anterior)
Triangles of the Neck
- The triangles of the neck are regions of the anterior and lateral neck used to describe the location of key features
- The boundary between the anterior and posterior triangle of the neck is divided by the Omohyoid muscle
Muscles and Attachments
- Sternocleidomastoid muscle:
- Attachments: from sternum and clavicle to mastoid process (temporal bone)
- Function: tilts and rotates the head (single), flexes head and raises sternum (paired)
- Trapezius muscle:
- Attachments: external occipital protuberance and superior nuchal line to ligamentum nuchae, spinous processes of T12, clavicle, and scapula
- Function: moves shoulder and scapula, extends the head
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