BIOL121 - Biology Notes PDF

MODULE 1: Levels of Organisation - Atoms to Organism Co-operative Hierarchy 1. Chemical and Molecular Levels - Atoms in combination - Complex protein molecule - Protein filaments 2. Cellular Level (heart muscle cell) - The basic unit of life - Cell numbers vary in health and disease 3. Tissue Level (cardiac muscle tissue) 4. Organ level (the heart) 5. Organ system level (cardiovascular system) - An organ system is a group of organs working together - Humans have 11 organ systems Functions - Control/Direct - Cool and warm - Digest - Move - Protect - Remove - Reproduce - Store - Support - Transport 6. Organism level - A human is an organism Atoms - smallest chemical unit of matter Molecules - a group of atoms working together Organ - a group of different tissues working together - Organ functions are supplied by tissues - Multi-tasking (e.g. skeletal muscle) - Specialists (e.g. heart) Tissue - A group of similar cells working together - Epithelial - Connective - Muscle - Neural Cells - a group of atoms, molecules and organelles working together Animal cell: Elements and Macromolecules Elements - Symbols = C, K etc - Ions and electrolytes (Na+, K+, Ca2+) Macromolecules - Proteins - Carbohydrates - Lipids/fats - Nucleic acids Functions - structure/form work - Storage - Messengers - Control Body Cavities TOPIC 1A: CHEMISTRY All substances are made of tiny particles called atoms. An element is a substance that is made of only one type of atom. The atoms of any element are different to the atoms of any other element. So nitrogen is made from a different type of atom to sodium, and carbon atoms are different to oxygen atoms. There are about 100 different elements. These are shown in the periodic table, which is a chart with all the elements arranged in a particular way. Atomic Structure As shown in the diagram below, an atom has a small central nucleus made up of smaller sub-atomic particles called protons and neutrons. The nucleus is surrounded by even smaller sub-atomic particles called electrons. Protons and electrons have an electrical charge. Both have the same size of electrical charge, but the proton is positive and the electron negative. Neutrons are neutral. The number of electrons in an atom is equal to the number of protons in its nucleus. This means atoms are neutral within overall electrical charge. Electronic Structure The electrons in an atom are arranged in energy levels, these are also called shells or orbits. Each electron in an atom is found in a particular shell. The innermost shell (lowest energy level) fills with electrons first. Each shell can only hold a certain number of electrons before it becomes full. The first shell can hold a maximum of two electrons, the other shells can hold up to a maximum of 8 electrons (only true for the first 20 elements). The outermost shell is also known as the valence shell and electrons that occupy the outermost shell are also known as valence electrons. Valence electrons are the electrons of an atom that can participate in the formation of chemical bonds with other atoms (see Chemical Reactions for more information). You can work out the electronic structure of an atom from its atomic number or its position in the periodic table. The number of occupied shells is the same as the period number (row in the table) and the number of electrons in the outermost shell (valence shell) is the same as the group number (column in the table). Molecules, Compounds and Ions Ionic Bonds https://youtu.be/TxHi5FtMYKk - Atoms can gain or lose electrons from their outer shell (valence shell) in chemical reactions. When they do this they form charged particles called ions. - When atoms lose electrons they form positively charged ions known as cations. When atoms gain electrons to form negatively charged ions known as anions. - Remember that electrons carry a negative charge and protons (in the nucleus) carry a positive charge. The diagram below shows that when an atom loses (or donates) an electron it becomes positively charged and when an atom gains (or accepts) an electron it becomes negatively charged. Covalent Bonds https://youtu.be/OTgpN62ou24 A covalent bond forms when two atoms share a pair of valence electrons. Hydrogen gas (H2) forms the simplest covalent bond - a molecule is formed by two individual hydrogen atoms joining together by sharing their single valence electron. Octet Rule: - The tendency of atoms to prefer 8 electrons in their outer shell Chemical Equations A chemical equation represents the total chemical change that occurs in a chemical reaction using words or symbols for the substances involved. Reactants are the substances that are changed and products are the substances that are produced in a chemical reaction. Sodium + Chlorine → Sodium Chloride The chemical formula of a compound tells you how many atoms of each element the molecule contains. Organic Compounds Organic compounds can be recognised from their formulae - they all contain the elements carbon and hydrogen. Examples of organic compounds are carbohydrates, lipids and proteins and nucleic acids. These may be classified as (a) small biological molecules and (b) large biological molecules and polymers. Inorganic Compounds These are compounds that are not made by living things. They usually do not contain the element carbon but there are a few exceptions (e.g. carbon dioxide and carbon monoxide). Other examples of inorganic compounds are water (which exists as molecules) and salts (which contain ions such as potassium, calcium and chloride). PH The pH Scale This is a scale from 0 – 14. The pH scale measures the hydrogen ion (H+) concentration of a substance and therefore how acidic or basic/alkaline a substance is. It ranges from 0 (strongest acid) to 14 strongest base), and a pH of 7 is neutral. An indicator is a chemical that changes colour when in contact with an acid or a base. Acids Acids have a pH lower than 7 (1 to 6), the lower the number the stronger the acid. Acidic solutions turn blue litmus paper red and turn universal indicator paper red if they are strongly acidic, and orange or yellow if they are weakly acidic. Bases/Alkalis Substances that can react with acids and neutralise them are called bases. Bases that dissolve in water are called alkalis. - Alkaline solutions have a pH greater than 7 (8 to 14). The higher the number the stronger the alkali. Neutral Solutions Neutral solutions have a pH of 7. They do not change the colour of litmus paper, but they turn universal indicator paper green. Distilled water is an example of a neutral substance. - When the H+ ions from an acid react with the OH– ions from an alkali, a neutralisation reaction occurs to form water. TOPIC 1B: CELLS, TISSUES AND MEMBRANES Combinations of many chemicals form our cells. Cells are the basic structural and functional units of the body. Each cell has a specific task and works with many other cells to help our body maintain homeostasis. A cell can be divided into three main parts: plasma (cell) membrane, cytoplasm, and nucleus. Organelles within the cytoplasm have specific functions related to cell structure, growth, maintenance, and metabolism. Functions of the Plasma Membrane - Maintains the composition of ICF and ECF - Determines movement of substances into and out of cells. - Communicates with other cells and organs (receptors) - Links adjacent cells Structural Features of the Plasma Membrane - Phospholipids - Hydrophilic phosphate heads - Hydrophobic lipid tails - Proteins (peripheral or integral) - Channels, gates or pumps - Carrier proteins - Receptors - Anchoring proteins Selective Permeability - Due to the structure of the membrane - Lipid biulayer - It lets some substances in or out of the cell, but stops other - Distinction based on - Solubility - Size - Charge NUCLEUS - Control of storage and processing of genetic information CYTOPLASM - Where most cellular activities occur, such as many metabolic pathways including glycolysis, and processes such as cell division RIBOSOMES - Protein synthesis ROUGH ENDOPLASMIC RETICULUM - Modifies and packages newly synthesised proteins. Ribosomes can be attached to this structure. MITOCHONDRIA - Produce 95% of the ATP required by the cell PLASMA MEMBRANE - Separates the interior of all cells from the outside environment. Controls the movement of substances in and out of cells. Tissues and Membranes Epithelial Tissue - Lining, covering - Functions: protection, absorption, filtration, excretion, secretion - Classified by shape and number of layers Connective Tissue - Functions - Support and bind other tissue - Provide insulation and protection - Classified according to physical properties - Connective tissue proper - Fluid connective tissue - Supporting connective tissue Muscle Tissue - Specialised for contraction - Types - Skeletal - Smooth - Cardiac Nervous Tissue - Primary function is communication - Types - Neurons (nerve cells) - Neuroglia (support cells) Membranes - Physical barriers that line parts of the body - Consists of - An epithelium - Supporting connective tissue TOPIC 1C: DIFFUSION AND OSMOSIS: The plasma membrane is selectively permeable, it allows the passage of some ions or molecules but restricts the passage of others. This distinction is based on: Size and shape – larger molecules cannot directly cross through the phospholipid bilayer. Electrical change – changed molecules cannot directly cross through the phospholipid bilayer. Lipid solubility – water soluble molecules cannot directly cross through the phospholipid bilayer. Passage across the membrane is either: Passive – it results from the random motion and collisions of ions and molecules (kinetic energy). Active – energy expenditure, generally in the form of ATP, is required. Membrane transport is categorised according to the mechanism involved: Simple diffusion – the movement of a molecule directly through the phospholipid bilayer from an area of higher concentration to an area of lower concentration (until the concentration is the same on both sides of the membrane). Facilitated diffusion – the movement of an ion or molecule from an area of higher concentration to an area of lower concentration (until the concentration is the same on both sides of the membrane), via a channel or carrier protein. Osmosis – the movement of water molecules to an area of higher solute concentration, where the concentration of water is lower. Active transport – the movement of an ion or molecule from an area of lower concentration to an area of high concentration, via a channel or carrier protein. Diffusion rates are influenced by: Distance – the shorter the distance, the faster the diffusion. Molecular size – the smaller the molecule size, the faster the diffusion. Temperature – the higher the temperature, the faster the diffusion. Concentration gradient – the steeper the concentration gradient, the faster the diffusion. Electrical force – opposite electrical charges attract each other and like charges repel each other. Tonicity A cell placed in a/an ISOTONIC solution would experience net flow of water no net flow of water in or out of the cell. A cell placed in a/an HYPERTONIC solution would experience net flow of water out of the cell. A cell placed in a/an HYPOTONIC solution would experience net flow of water into the cell. TOPIC 1D: HOMEOSTASIS Homeostasis – the body’s ability to maintain a stable (balanced) internal environment in the face of variable external conditions through constant interactions of the body’s many regulatory processes. In other words, homeostasis is your body’s ability to detect when something is out of balance, to process this information and to bring about changes that will restore balance. For example, the normal levels of glucose in your blood sit somewhere between 70 – 110 mg/100 ml. This range is maintained through regulatory systems such as the interplay between insulin and glucagon (you will learn more about these hormones later in semester). Feedback System - Cycle of events in which body conditions are: - Monitored - Evaluated - maintained/changed - Re-evaluated Components 1. Controlled condition - Variable that is monitored 2. Stimulus - Any disruptions to the controlled condition 3. Receptors - Detects change and notifies the control centre 4. Control centre - Sets the range - Receives information from the receptor - Evaluates and processes the information(determine what action to take) - Sends output commands to effector 5. Effector - Receives commands from the control centre and produces the response 6. Response - Effect that changes the controlled condition Positive & Negative Feedback Increasing body temperature when in a cold environment - NEGATIVE Blood clotting sop blood flow from an open wound - POSITIVE Increasing calcium levels in blood when they are low - NEGATIVE An decrease in heart rate after stopping exercise - NEGATIVE Milk letdown when breast feeding - POSITIVE An increase in respiratory rate at high altitudes - NEGATIVE Release of glucagon to increase blood glucose levels - NEGATIVE MODULE 2: TOPIC 2A: PRINCIPLES OF MICROBIOLOGY What is a microorganism - Tiny living organisms - Living organisms can reproduce independently - Viruses & prions not ‘living’ - Everywhere - Essential for the decomposition & recycling of nutrients - Affect our everyday life Prokaryote vs Eukaryote PROKARYOTE No nucleus or membrane-bound organelles EUKARYOTE Separate nucleus and membrane-bound organelles PROKARYOTE EUKARYOTE - Small (under 5 millionths of metre) - Large (over 5 millionths of a metre) - Unicellular - Multicellular - Organelles have no membrane - Organelles have membrane - Asexual reproduction - Sexual reproduction Virus - Not living - No cellular structures - Protein capsule around DNA or RNA - Can mutate - Antibiotics are ineffective (antivirals instead) - Size = billionths of a metre Bacteria - Prokaryote - Mostly uni-cellular - Different shapes - Have cell wall (thickness important) - E.g. conditions - Salmonella - Golden Staph - Syphilis Protozoa - Eukaryotic cells - Unicellular - Usually motile - Size from 1 to 150 microns (millionth of a metre) - Examples - Giardia - Malaria - Cryptosporidium Fungi - Eukaryote - Uni- or multi-cellular - Has cell wall - Produce spores - Size about 2-10 microns - Examples - Tinea - Ringworm - Aspergillus Helminths - Eukaryote - Multi-cellular - Large (organ systems) - Eggs/larva/adult - Don’t proliferate in host - Examples - Cestodiasis] - (Tapeworm infestation) - Ascariasis - Guinea worm Microbiology - Bacteria Temperature - most between 10 degrees C - 39 degrees C Pathogenic bacteria optimum ~37 degrees C THERMOPHILE MESOPHILES PYSCHROPHILES (heat-loving) (love moderate temps) (cold-loving) Optimum 60 degrees C Optimum 25 - 30 degrees C Optimum 10 degrees C Bacteria - Growth Requirements pH - most close to neural ~ pH 7 (variable depending on the organism) Helicobacter pylori have enzymes which enable them to survive quite happily at pH 3.5 found in stomach antrum (area closest to the small intestine). This enables them to survive and potentially cause ulcers. Bacteria - Gram Stain Structural difference in cell wall - Gram positive - thick layer of peptidoglycan - Gram Negative - reinforced with 2nd membrane GRAM +VE GRAM -VE - Capable of forming spores - More difficult to kill! - (spores survive extreme conditions - Produce endotoxins – e.g. Clostridium difficle) (endotoxins released when bacteria - Reinfection +++ die, can cause sepsis - ?fatal) e.g. Staphylococci, Streptococci, e.g. E. coli, Salmonella, Neisseria Pneumococci, Clostridia.. Pseudomonas, Legionella... Normal Flora (microbiota) - Our bodies have microbes in residence on various areas - Bacteria 10x more than human cells - Resident flora - colonised/transient - Hygiene Beneficial Roles Skin - Reduces pH - Change environmental conditions - Not ideal for other species Oral & Vagina - Completes & inhibits pathogens & yeasts Intestine - Excrete antibacterial chemicals - Synthesise and secrete vitamins (esp. Vit. K) - Stimulate local immunity (lymphatic tissue, Ig) Possible Harmful Effects - Competition for nutrients - Bacterial synergism: normal flora & pathogen - Endogenous disease: fever, inflammation, cancer - Opportunistic infection: overgrowth, infection. Common Causes of Opportunistic Infection - Genetic predisposition - Chemotherapy or other therapies that impact immunity - HIV/AIDS - Bone marrow disease - Pregnancy Microbiology - Transmission Mode of Transmission Contact - Is contact between people, either directly via touch or indirectly via two people touching the same inanimate object Vehicle - Is transmission of pathogens via vehicles such as air, water, food (COVID) Vector - Transfer of pathogens via an animal (often arthropods like mosquitos or ticks) Vector-Borne - Mosquito - RossRiver, Barmah Forrest, Malaria - Tick - Australian tick typhus Fomite-Borne - Transmission via an inanimate object (COVID) Vertical (transplacental) - Intrauterine and postpartum Chain of Infection Environmental Control STERILISATION Destruction/elimination of ALL microbes - Methods Heat– dry (e.g. burning) / moist (e.g. boiling) Heat & pressure – e.g. autoclave Radiation Filtration Chemical – e.g. bleach, hydrogen peroxide DISINFECTION Elimination of MOST pathogens from inanimate objects - Methods Chemical – e.g. alcohol, chlorine Gas – e.g. formaldehyde SANITATION Safe disposal of human urine and faeces TOPIC 2D: INTEGUMENTARY SYSTEM (SKIN) The Skin - Covers the entire body - Surface area = 1.2 - 2.2 square meters - Is the largest organ of the body - Weighs 4-5kg (7% of total body weight) - Is a major component of the integumentary system - Skin, glands, hair and nails - Integument = covering Layers of the Skin EPIDERMIS DERMIS HYPODERMIS - Outermost layer - Derm = skin - Hypo = under - Composed of epithelial cells - Deep to the epidermis - Subcutaneous layer, not - Keratinised stratified - Makes up the bulk of skin really part of the skin - Composed of connective - Lies beneath the dermis squamous epithelium tissue - Also called the superficial - Thinner portion of the two - Mainly collagen fascia (band) - Avascular - Highly vascularised - Anchors the skin to - No blood vessels - Highly innervated underlying structure - Stores fat EPIDERMIS - 4 distinct cell types 1. Keratinocytes - most abundant, produces keratin, arises from the deepest layer of the epidermis 2. Melanocytes - spider-shaped cells, produces melanin, found in the deepest layer of the epidermis 3. Langerhan’s cells - star-shaped macrophage cells, activate immune system, originate from bone marrow 4. Merkel cells - present at the epidermis-dermis junction, associated with nerve endings, function as sensory receptors Layers of the Epidermis 1. Stratum basale (deppest layer, sits on top of dermis) 2. Stratum spinosum 3. Stratum granulosum 4. Stratum lucida 5. Stratum coneum (outermost layer, what you see) DERMIS - cell types - Fibroblasts - Macrophages - Some mast cells - White blood cells Layers of the Dermis Papillary - Thinner of the two layers - Superficial to the recticular layer - Sits directly underneath the stratum basale of the epidermis Reticular - Thicker of the two layers ~80% of the dermis - Deep to the papillary layer - Lots of collagen to stop penetration Skin Colour 1. Melanin - Pigment make in skin (melanocytes) - Exposure to UV increases melanin synthesis - Darker skin due to more melanin, and type of melanin produced, not more melanocytes 2. Carotene - yellowish/orange pigment (found in carrots) - Accumulates in the stratum corneum 3. Hemoglobin - Red pigment of blood - Gives fair-skinned people a ‘pinkish hue’ 4. Redness - Embarrassment, fever, hypertension, inflammation, allergy etc 5. Parlour - Fear, anger, anaemia, hypotension 6. Jaundice - Liver disorder (accumulation of yellow bile in tissues) 7. Black/blue (bruises) - Blood has escaped from vessels and clotted beneath the skin = hematoma (blood mass) What, Where Why? WHAT WHERE WHY NAILS modifications of the located distally on the protection of the underlying epidermis, densely packed posterior surface of the nerves aids in picking things epithelial cells containing fingertips and distally on the up, scratching, digging, fibres of hard keratin superior surface (kera = horn) of the toes GLANDS clusters of specialised sweat glands: whole body sweat glands: regulate body epithelial cells that secrete a except nipples and parts of temp, remove wastes substance. eg, oil, sweat, external genitalia sebaceous glands: softens wax, milk, etc sebaceous glands: whole body skin and hair, ↓bacterial except palms and soles growth, ↓ water loss HAIR shaft: slender filament of whole body except palms, warmth, protection against keratinised cells root: below soles, lips, nipples and parts physical trauma, heat loss, the surface, embedded within of the external genitalia sunlight, detect insects on skin skin, keep out foreign - follicle: group of cells tha particles, etc surround the root, holds hair in place Functions of the Skin’ 1. Protection The skin is the most vulnerable organ of the body. It is constantly exposed to bacteria, abrasions, temperature extremes, chemicals, etc Acts as 3 types of barriers: - Chemical barrier: Skin secretions and melanin - Physical barrier: Continuity of skin, waterproof - Biological barrier: Langerhan’s cells, macrophages 2. Body temperature regulation Sweating - 500ml/day at rest (unnoticeable) - up to 12L/day during vigorous exercise 3. Cutaneous sensation Sensory receptors on the skin allow us to feel light touch, pressure, vibration, tickling (mechanoreceptors), temperature (thermoreceptors), pain (nociceptors), etc Hair follicle receptors – insects, wind, etc 4. Metabolic function Produces vitamin D (when exposed to UV) for calcium and phosphorous absorption (bone development) 5. Blood reservoir The dermis is highly vascularised - Blood can be temporarily shunted from the skin and relocated to another part of the body that requires it 6. Excretion and Absorption Removal of nitrogenous wastes such as urea, ammonia, uric acid, and salts, etc in sweat. Absorbs vitamins A, D, E and K and oxygen Effects of Aging on Skin - ↓Basal cell activity, epidermis thins → ↑injuries, tears, infections, etc - ↓Langerhan cells → ↓immune sensitivity → ↑skin damage and infections - ↓ Vitamin D production → ↓calcium and phosphorus absorption → muscle weakness and bone degradation - ↓ melanocyte activity → skin becomes pale and more likely to get sunburn, hairs go grey - ↓ glandular activity → ↓thermoregulation, ↑dry skin - ↓blood supply to dermis → cool skin → activates thermoreceptors → elderly often “feel cold” - ↓elastic/collagen fibres in dermis → sagging and wrinkling - ↑time taken for repairs TOPIC 2B: LYMPHATICS 1. Drains excess fluid & proteins from all tissues back to blood circulation 2. Defends the body against external and internal threats (immunity / resistance to diseases) 3. Transports fats and vitamins from gut to liver (digestion) 1. Immune cells 2. Lymph fluid 3. Lymph vessels 4. Lymphatic organs & tissues - Lymphocytes - key players - Produced from the same precursor cell in the bone marro - Mature in bone marrow or thymus LYMPH - Means “fluid” - Fluid connective tissue - Contains lymphocytes & macrophages + enemies they seek out & destroy - foreign cells (microbes) - Foreign proteins - Cancer cells - Plasma proteins & RBC usually not found blood plasma(from capillaries) ↓ interstitial/tissue fluid ↓ lymphatic capillary ↓ lymph vessels, trunks & ducts ↓ blood plasma (vein at base of neck) i - Capillaries that begin as blind ended tubes - Structure similar to blood capillaries - One layer of epithelial (endothelial) cells supported by basement membrane - Structure helps to let fluid in, but not out - overlapping endothelial cells open when tissue fluid pressure is high (one-way valve) - Fluid inside is called “lymph” - Lymph capillaries in intestinal villi = Lacteals - Thin walls - Resemble veins; have more valves - Have lymph nodes at intervals - Respiratory & muscular pumps promote flow of lymph towards large veins/heart - Vessels unite to form 2 thoracic ducts - Right side head, arm & chest empty into right lymphatic duct - Left side and lower body empties into main thoracic duct (largest vessel) - Lymph from ducts flow into left & right subclavian veins Lymphatic Organs and Tissues Primary lymphatic organs - Red bone marrow - Thymus Secondary lymphatic organs - Spleen - Lymph nodes Diffuse lymphatic tissue - tonsils, adenoids & Peyer’s patches Red Bone Marrow - In flat bones - At end of long bones - Contains haemopoietic stem cells - Produces & matures B cells and make pre - T cells (lymphocytes) Thymus Gland - in the mediastinum - large in infancy - max size (70g) at puberty - atrophied (3 g), but functional in adulthood T cells mature here Thymus makes thymosin hormones for development and maturation of T cells Lymph Nodes - Size 1 - 25 mm - Along lymphatic vessels (esp. Near neck, axillae & inguinal area) - Multiply lymphocytes; “finishing school” for B cells - Filter lymph: Afferent vessels brings lymph with foreign material into node - foreign matter trapped in fibres - destroyed by macrophages, B & T cells - Efferent vessel leaves node with cleaner lymph Spleen - Between stomach and diaphragm - Macrophages remove worn- out or defective RBCs, WBCs, and platelets. - Stores & releases blood & blood cells - Site of production of blood cells during the second trimester of pregnancy - MALT: mucosa-associated lymphoid tissue - Nodules scattered in connective tissue layer in the mucous membranes Examples - Tonsils - Peyer’s patches in the small intestine - Appendix What is Oedema? - Excessive accumulation of interstitial fluid in tissue spaces due to: - blood pressure - obstruction to lymph flow TOPIC 2C: BODY DEFENCES What is an Anitigen? - Anything capable of inducing an immune response - Anything foreign to you as the host Examples: - Microbes or their parts - Protein from other species (rabbit serum, dust mite, cat hair, pollen) - Transplanted tissue from other humans/animals Body Defenses Non-specific (innate) - General defence/attack on all antigens - Inborn - First and second line defences Specific (acquired or adaptive) - specialist/targeted defence against one type of antigen - Acquired during life - Third line defences Non-specific defences General properties - Do not distinguish between threats - React same each time as first time - Present at (before) birth - Second line defenses respond to tissue damage caused by pathogens or ‘mechanical’ means First Line Defences Non-specific Aim - keep every invader out/deny entry the SAME way via chemical and physical barriers 1. Skin - epidermis, sebum, sweat 2. Mucous membranes - mucous +_ hairs, cilia 3. Fluids that help protect these surfaces - tears, saliva, nasal secretions, urine, gastric juice 4. Defecation and vomiting, coughing and sneezing Second Line Defences Act once microbes have entered the body Non-specific: ANY invader inside is attacked the SAME way 1. Antimicrobial chemicals 2. Phagocytes 3. Natural killer cells 4. Inflammation 5. Fever 1. Antimicrobial Chemicals Interferon interferes with viral replication and activates immune cells - Made by infected host cells and WBC - Effective against bacteria as well Complement is a set of plasma proteins that ‘complements’ all aspects of the immune response - All of these “support” the immune cells 2. Phagocytes Phagocytosis = cell eating Phagocyte = cell that eats - Fixed or free - Attracted to the effected site by chemotaxis - Destroy bugs and clean up dead tissues - Where? (connective tissue, wandering) 3. Natural Killer Cells Immune serveillance - targets abnormal cells Abnormal cells? - Bacteria in interstitial fluid - Virus infected cells - Cancer cells 4. Inflammation - Damaged cells send out chemical messages - Body responds with inflammation - This process is supported by phagocytosis - Destroys and removes antigens: immune response - Limits effects of injurious agent - Cleans up dead tissue and debris - Promotes healing 5. Fever - Systemic response - Temperature regulator in hypothalamus is reset - Body tries to attain temperature above 37.2 degrees C - Help by destroying bugs whose enzymes cannot work at high temperature - Higher metabolic rate to help healing Thirs Line Defences Specific Immunity (aka adaptive or acquired immunity) - Develops an exposure to a particular antigen - Antigens from microbes, “wrong” cells - Uses B and T lymphocytes made in bone marrow - B cells mature in bone marrow; T cells mature in thymus Properties of Specific Defenses Specific - 1 antigen - 1 response Versatile - many threats! Memory - formed after first exposure Tolerance - must exist toward own cells (antigens) Overview of the Specific Immune Response Humoral Immunity: B-lymphocytes - B-cells make antibody (immunoglobulin) against the antigen; antibody-mediated immunity - Aka humoral immunity = antibodies work in the body humours (body fluids) - Destroy microbes/toxins that circulate in blood and body fluids e.g. bacteria Humoral Immunity: Antibodies - Made against antigens - Stay in blood & lymph nodes or attached to B-cells - Can be measured in blood: “titre” - 1 antibody type for each antigen..... a match! - Inactivate and/or target antigens for destruction Defense Against Bacteria - Bacteria live between cells, on epithelial surfaces, in fluids - Attacked mostly by antibodies from B cells - Helped by non-specific defences (e.g. fever, pH) Two Ways to Activate B-cells 1. Phagocyte (APC) engulfs bacteria & “presents” antigens to helper T-cell....... 2. Antigen attaches to antibodies on surface of B-cells “Humoral Immunity” has memory - EVERY different antigen will cause a dedicated plasma and memory cell to be made… - the memory cell will remember.... - and produce antibodies instantly next time it sees that same antigen Cell-mediated Immunity: T lymphocytes T cells kill abnormal cells directly - don’t make antibody - viruses inside your host cells - fungal cells - transplanted tissue - cancer cells Also form memory cells...immune memory Types of T cells Definitions - IMMUNE SYSTEM ALL body cells and tissues involved in production of immunity - T CELLS Lymphocytes that mature in the thymus gland. Associated with cell-mediated immunity. - ANTIBODY Proteins produced by plasma cells in response to a specific antigen. Combines with that antigen to neutralise, inhibit or destroy it. - LYMPHOCYTE A type of white blood cell that helps carry out cell-mediated and antibody-mediated immune responses; found in blood and lymphatic tissues. - PATHOGEN Microbes capable of causing disease - B CELLS Lymphocytes that complete their development in red bone marrow. Associated with antibody-mediated immunity. - IMMUNITY Being resistant to injury, particularly by poisons, foreign proteins and invading pathogens. i.e. resistant to infection and disease - PLASMA CELLS Cells that develop from B cells and produce antibodies. - ANTIGEN Antibody generator. A substance (often a protein) that can provoke an immune response and react specifically with the antibodies or cells it provoked. - Of or relating to the skin INTEGUMENTARY - The body's most abundant epithelial cells. These cells form layers or strata and contain large amounts of the protein keratin KERATINOCYTE - A cell of the lymphatic system that plays a role in the immune response LYMPHOCYTE - The native microbial forms that an individual harbors NORMAL FLORA - A large, active phagocytic cell derived from monocytes MACROPHAGE - A protein produced by plasma cells that will bind to specific antigens and promote their destruction or removal from the body ANTIBODY - A molecule capable of inducing an immune response ANTIGEN macr- large -itis - inflammation phago - to-eat a- without sub - below MODULE 3: TOPIC 3A NERVOUS SYSTEM: STRUCTURE Main Parts of the Nervous System 1. Central Nervous System (CNS) - Brain - Spinal Cord 2. Peripheral Nervous System (PNS) - All neural tissue outside the CNS (peripheral nerves) Histology of the Nervous System Main cell types in the nervous system 1. Neurons - The functional unit of the nervous system - Cell body (soma) - Contains all the major cell organelles, including the cell nucleus - Generates genetic information and machinery for protein synthesis - Dendrites - Numerous, highly branched neuronal processes - Receive input from other neurons and convey it to the cell body - Provide a receptive area that transmits electrical messages to cell body - Axon - A single, long process - Carries electrical impulses in the form of action potentials - Away from the cell body to other neurons or effectors - Conducts impulses away from the cell body - Axon terminal - Essential for synaptic transmission to occur - Contains a specific messenger molecule (neurotransmitter), which is released when an action potential arrives - Myelin Sheath - A special, fatty covering around some of the axons → myelinated axons - Myelinated axons conduct electrical impulses faster and more effectively - Myelinated axons are white → ‘white matter’ - Cell bodies and dendrites are not myelinated → they have a darker, greyish tone → ‘grey matter’ - Nodes of Ranvier - Gaps between adjacent segments of myelin 2. Glia (neuroglia, glia) - Glial cells have many functions; all of those are essential for the survival, well-being and functions of neurons. They: - Support, nurture and protect nerve cells - Help maintain homeostasis - Fight pathogens and remove damaged and dead cells - Maintain K+ balance in the extracellular space - Make and circulate cerebrospinal fluid - Produce myelin sheath - Contribute to nerve regeneration (but only in the peripheral nervous system) Neuronal Communication Resting Membrane Potential - The inside of living cells is more negative than the outside - Resting membrane potential → -70mV Why does resting membrane potential develop? - Highly asymmetric K+ ion concentration on the 2 sides of the membrane - ‘Na/K+ exchanger’ *intracellular K+ concentration: 4mM - *Extracellular K+ concentration: 150mM - High K+ permeability of the cell membrane *Presence of ‘leaky’ K+ channels in the membrane - ‘Selectively permeable membrane’ Action Potentials - In neurons, the resting membrane potential may rapidly and reversibly change → Action potential - Action potential is the language neurons speak when communicating with each other - Na+ and K+ channels = pores in the cell membrane that allow the movement of Na+ and K+ ions - Na+ channels open when the membrane gets depolarised and allow entry of Na_ ions → further depolarisation - K+ channels open when the membrane gets strongly depolarised and allow exit of K+ ions → depolarisation Action potentials are generated at the beginning of an axon, and then they propagate along the entire length of the axon - Axon hillock = white it gets decided if an action potential will be fired or not - If we block action potential conduction, we prevent painful stimuli from reaching the central nervous system - Some drugs inhibit the opening of Na+ channels → no action potential can be fired → no pain sensation → (local) anaesthesia - Lidocaine blocks voltage-gated Na+ channels and thus prevents action potential firing and conduction- → local anesthesia Synaptic Transmission Synapse = a specific structure that allows a neuron to communicate with another cell - The presynaptic terminal contains synaptic vesicles (little sacs that contain neurotransmitter molecules) - Neurotransmitter = a messenger molecule that is released from the presynaptic terminal and acts on the postsynaptic cell How does a synapse work? - Electrical impulse (action potential) arrives - Evokes release of neurotransmitter - Neurotransmitter binds to postsynaptic cell membrane - A new electrical impulse is generated on the postsynaptic cell Neurotransmitters - Chemical messengers - Excite or inhibit the postsynaptic neuron/cell - Drugs may mimic, enhance, or dampen down the effects of neurotransmitters Synaptic Transmission 101 - Action potential travels along the axon and reaches the presynaptic terminal - Ca2+ channels open - Ca2+ ions enter the presynaptic terminal - The neurotransmitter (e.g., acetylcholine) gets released into the synaptic cleft by exocytosis - The neurotransmitter binds to postsynaptic receptor molecules - Ion channels open in the postsynaptic membrane, which may result in action potential firing of the postsynaptic cell - Action potential propagates along the postsynaptic cell How are the Effects of Neurotransmitters terminated? - Enzymatic degradation in the synaptic cleft (e.g. acetylcholine) - Reuptake by the presynaptic terminal (e.g. glutamate) - Uptake by glial cells (e.g. glutamate) - Diffusion out of the synaptic cleft TOPIC 3A: NERVOUS SYSTEM: CENTRAL NERVOUS SYSTEM Central Nervous System Structure and Function Sensory Division of the Nervous System - Sensory system → receives information from the environment and body → knows what is happening - Afferent Division → brings information to the central nervous system Motor Division of the Nervous System - Motor system → sends information to muscles and glands so that they do something (move or secrete something) - Efferent division → carries information from the central nervous system Integrative (control) Part of the Nervous System - Makes decisions based on the sensory input, and then instructs the motor system to do something - Integrative system = central nervous system Efferent Division of the Peripheral Nervous System → Somatomotor System - To skeletal muscle → voluntary and involuntary movements (including various reflexes) - One-neuron pathway → Autonomic Nervous System - To smooth muscles, cardiac muscles and glands → controls autonomic functions - Two-neuron pathway Main Parts of the Brain 1. Cerebrum 2. Diencephalon a. Thalamus b. Hypothalamus 3. Cerebellum 4. Brainstem a. Medulla b. Pons c. Midbrain The corpus callosum serves as the main connection pathway between the two cerebral hemispheres Grey matter (outside) and white matter (inside) Spinal Cord A flattened cylinder, about 45cm long - Does not go all along the spine; it ends at the level of the L2 vertebra (roughly at the level of your elbows in a standing position) Cerebrum 1. Frontal - Accommodates motor centres that initiate and are essential for voluntary movements - Hosts the motor speech centre (Broca’s area; one side only) - Involved in short-term memory formation - Controls behaviour, personality, mood and motivation - Plays a part in smell, plus dealing with motor function 2. Parietal - Sensory integration - Accommodates the primary somatosensory cortex - Handles all the sensory info except for vision, hearing, and smell. 3. Temporal - Accommodates the auditory cortex as well as the sensory speech centre (Wernicke’s centre; on one side only) - Involved in smell sensation - Involved in hearing and smell. You can find this by looking on the outside of one of the hemispheres. You will see a horizontal groove called the lateral fissure. This structure is the section of the cerebrum below this line. 4. Occipital - Accommodates the visual cortex - Essential for visual processing - Receives and interprets visual sensory messages Parts of the Diencephalon - Thalamus - Sensory relay station - connects sensory pathways to the cortex - Controls the amount of sensory information reaching the cortex - Involved in pain perception - Involved in motor control - Controls emotions and motivation Parts of the Diencephalon - Hypothalamus - Autonomic functions (e.g. controls satiety and hunger, features the thermoregulatory and thirst centres) - Involved in controlling circadian rhythm, provides the highest level of control for the endocrine apparatus, produces hormones (ADH and OXT), and integrates the function of the endocrine and nervous systems - Influences emotions and behaviour Cerebellum - Involved in movement control (including eye movements) - Coordination of skilled voluntary movements - Adjusts muscle tone Brainstem Midbrain - reflex centre for head and eye movements Pons - accommodates some of the respiratory centres + connects the medulla and cerebellum to the rest of the brain Medulla Oblongata - Connects the spinal cord to the brain - Various sensory and motor pathways pass along the medulla; most of them cross the midline - Accommodates respiratory and cardiovascular centres as well as the swallowing and vomiting centres MEDULLA OBLONGATA Is located right under the cerebellum. In this the nerves cross over so the left hemisphere controls the right side of the body and vice versa. This area of the brain controls the vital functions like heartrate and respiration (breathing) PITUITARY GLAND Is a sac-like area that attaches to the brain between the pons and the optic chiasm. Produces important hormones. CEREBRUM Associated with higher brain function. It enables us to be aware of ourselves and our sensations, to communicate, remember, understand and initiate voluntary movements THALAMUS Receives messages from the nerve axons and then transmitters them to the appropriate parts of the brain CEREBELLUM Provides precise timing and appropriate patterns of skeletal muscle contraction for smooth coordinated movements PONS Is next to the medulla. It serves as a bridge between the medulla and the upper brainstem, and it relays messages between the cerebrum and the cerebellum SPINAL CORD Transmits neural signals between the brain and the rest of the body HYPOTHALAMUS Responsible for hormone production. Controls ANS initiates physical response to emotions, regulates body temperature, regulates food intake, regulates water balance & thirst, and regulates the sleep-wake cycle CORPUS CALLOSUM Is a bundle of white fibres that connects the two hemispheres of the brain, providing coordination between the two Spinal Cord - Conducts sensory information from the receptors to the brain - Conducts motor information (commands) from the brain to effector organs (muscles and glands) - Serves as a reflex centre Cervical Enlargement - Accommodates all the cell bodies of neurons that supply skeletal muscles of the UPPER limbs Lumbar Enlargement - Accommodates all the cell bodies of neurons that supply skeletal muscles of the LOWER limbs Spinal Cord - Cross Section - Grey matter on the inside (forms an H- or butterfly shaped structure) - While matter on the outside - The central canal accommodates cerebrospinal fluid - Nerve roots → Spinal nerves are attached to the spinal cord - Dorsal root: sensory 9afferent) information is coming into the spinal cord - Dorsal root ganglion → accommodates the cell bodies of the sensory neurons whose axons enter the spinal cord via the dorsal root - Ganglion: a structure containing a number of nerve cell bodies; often forming a swelling on a nerve fibre. - Ventral root: Motor information is leaving the spinal cord and proceeds to (mainly) muscles. - The dorsal and the ventral roots converge and form a spinal nerve, which contains both afferent and efferent (e.g. sensory and motor) fibres. Spinal Nerves We have 31 pairs of spinal nerves: - 8 pairs of cervical - 12 pairs of thoracic - 5 pairs of lumbar - 5 pairs of sacral - 1 pair of coccygeal Cranial Nerves - Twelve pairs - Numbered in Roman numerals (I – XII) - Numbered front to back - All, except one, work locally (i.e., head/neck region) - Vagus nerve (X): leaves the head-neck region and passes down to the thoracic and abdominal cavities Efferent division of the peripheral nervous system Somatomotor system - To skeletal muscles → voluntary and involuntary movements (including various reflexes) - One neuron pathway Autonomic nervous system - To smooth muscles, cardiac muscle and glands → controls autonomic functions - Two neuron pathway - Sympathetic nervous system - Fight of flight reaction→ prepares the body for an emergency (increased HR, increased RR, inhibition of the intestines) - Most body systems are affected - Parasympathetic nervous system - Rest and repose effect (decreased HR, increased intestinal mobility - Some systems are affected Nerves and reflexes What is a reflex? ‘An automatic and often inborn response to a stimulus that typically involves a nerve impulse passing inward from a receptor to the spinal cord and then passing outward from the spinal cord to an effector (such as a muscle or gland) without reaching the level of consciousness and often without passing to the brain.’ TOPIC 3A; NERVOUS SYSTEM: PERIPHERAL NERVOUS SYSTEM RARE PATHWAY ADRENAL MEDULLA Sympathetic Versus Parasympathetic Divisions - Note the different neurotransmitters at the second synapse (noradrenaline versus acetylcholine) - Note the difference in the locations of the ganglia - Note the functional differences (i.e., fight or flight versus rest and repose reactions; widespread versus localised response) - Note the difference in the locations of the preganglionic neuronal cell bodies (e.g. where do the relavent nerves originate from?) - They originate from the thoracolumbar segments of the spinal cord → THORACOLUMBAR ORIGIN - Parasympathetic nerves originate from the brain stem and sacral segments of the spinal cord → CRANIOSACRAL ORIGIN 1. Sympathetic ganglia are close to the CNS 2. Short preganglionic fibres 3. Long postganglionic fibres WEEK 3 VOCAB, PREFIXES AND SUFFIXES - An electrical signal that propagates along the membrane of a nerve or muscle cell ACTION POTENTIAL - An atom or molecule having a positive or negative charge due to the loss or gain of electrons ION - A single protein or protein complex that traverses the lipid bilayer of a cell membrane. In doing so, it forms a channel to facilitate the movement of ions through the membrane according to their electrochemical gradient ION CHANNEL - A chemical compound released by one neuron to affect the membrane potential of another NEUROTRANSMITTER - This site of communication between a nerve cell and some other cell SYNAPSE - A rapid, automatic response to stimulus REFLEX - Carry information towards the CNS. AKA afferent neurons SENSORY NEURONS - Carry information away from the CNS. AKA efferent neurons MOTOR NEURONS MODULE 4: TOPIC 4A: MOVEMENT AND SUPPORT: SKELETAL SYSTEM Your skeletal system includes the bones of the skeleton plus cartilages, ligaments, and other connective tissues that stabilise or interconnect the bones. The skeleton is the support structure of the body. It is primarily formed from bone (or osseous tissue), a hard, dense connective tissue that makes up about 18% of the weight of the human body (Tortora et al., 2019). It is worth noting that cartilage, ligaments, and tendons are avascular connective tissues (i.e., they lack blood vessels), so all exchange of nutrients and wastes must occur via diffusion through the extracellular matrix. Clinically, this means these tissues tend to heal more slowly when damaged compared to tissues with a good blood supply (e.g., bone). There are two divisions of the adult skeleton: the axial and appendicular skeleton (Figure 2). The axial skeleton has 80 bones and forms the longitudinal axis of the body. It comprises about 40% of the bones in the human body, including the skull and bones associated with the skull (e.g., hyoid bone), the vertebral column (cervical, thoracic, lumbar), and the thoracic cage (sternum and ribs) (Tortora et al., 2019). The appendicular skeleton includes all bones of the upper and lower limbs and the supporting bones (pectoral and pelvic girdles) that connect them to the trunk (126 bones in total) (Tortora et al., 2019). Your appendicular skeleton lets you manipulate objects and move from place to place. The appendicular skeleton is dominated by long bones. Axial and Appendicular Skeleton Bone Anatomy and Physiology Bone Composition - Bone = CT with lots of hard background matrix (osseous tissue) surrounding widely separated cells - 55% crystallised mineral salts, 30% collagen, 15% water - Mineral salts mainly calcium phosphate with calcium hydroxide hydroxyapatite crystals - Mineral salts are incorporated into the collagen fibre framework where they crystalise and harden calcification Properties of Bone - Crystallised salts and collagen fibres together are responsible for the properties of bone - Hardness and rigidity of bone provided by crystallised mineral salts; resists compression forces - Flexibility of bone from collagen fibres (like metal reinforcement rods in concrete) - Tensile strength of bone from lots of collagen fibres resistant to stretching and tearing - Collagen fibres bend out of the way under compression forces Bone Classification - By shape - By structure - Compact versus spongy bone - Organic versus inorganic components Bone Shapes FLAT LONG SESAMOID SHORT IRREGULAR Protect internal function small bone formed in provide provide attachment organs and as levers tendon; protect stability, support sites for ligaments attachment site tendons by helping and for muscles overcome limited motion compression forces Organic and Inorganic Components of Bone Organic: gives flexibility and great tensile strength to bone ability to resist tearing, stretching and some twisting forces - Primarily collagen fibres - Approximately one-third of the matrix weight Inorganic: gives hardness, rigidity, ability to resist compression forces and supports body tissues - Minerals of calcium, ions, phosphates and carbonate - Approximately two-thirds of the matrix weight Long Bone Anatomy - Diaphysis: bone shaft of compact bone - Metaphysis: joins diaphysis and epiphysis; spongy bone below the layer of compact bone - Epiphysis: ends of bone; spongy bone below the layer of compact bone - Red marrow: in spongy bone; blood cell production - Yellow marrow: in the medullary cavity; lipid storage - Articular cartilage: protects bone ends Periosteum and Endosteum - Periosteum: on the outside of bone - Two layers (fibrous outer & cellular inner) - Endosteum: in medullary cavity and covering spongy bone - Contains bone cells Bone Cells Four types of bone cells - Osteogenic or osteoprogenitor cells (stem cells) produce osteoblasts - Osteoblasts build bone with both organic & inorganic components; when surrounded by matrix osteocytes - Osteoclasts secrete acids and enzymes to break down/resorb bone (resorption) - Above cell types are located in the periosteum and endosteum (see Figure previous slide ) - Osteocytes maintain matrix and mineral content - Located within bone matrix in lacunae Spongy and Compact: why two different types of bone? The combination of compact and spongy bone structure provides support, strength, and protection whilst being lightweight - Ideal strength for weight bearing (compact and spongy bone) - Resists compression (compact bone) - Resists forces applied from different angles (spongy bone) - Less ATP needed for movement (spongy bone) 1. Located beneath periosteum of all bones. Diaphysis of long bones. This describes a COMPACT BONE 2. Located within epiphyses of long bones; interior of some large bones (e.g., sternum or ilium) This is a SPONGY BONE 3. The function of this bone is to support, protect, resist stress produced by weight and movement COMPACT 4. Provides some support and stores red bone marrow SPONGY 5. Resists forces applied from different directions and is lightweight SPONGY 6. Withstands compression; strong; supports weight COMPACT 7. Trabeculae and has many spaces in the arrangement of its tissue SPONGY 8. Parallel osteons and has few spaces in the arrangement of its tissue COMPACT 9. Also known as trabecular or cancellous bone SPONGY 10. Also known as cortical bone COMPACT TOPIC 4B: MOVEMENT AND SUPPORT: JOINTS Joint Classification - Joints = arthroses = articulations - Any place where adjacent bones or bone and cartilage come together (articulate with each other) to form a connection - Joints classified two ways: - Structurally i.e. by anatomical components - Classification depends on presence or absence of a space/cavity between articulating bones and type of CT - Functionally i.e. by the range of movement (articulation) permitted at the joint - Classification depends on the degree of movement Structural Classification - Fibrous joints - No joint cavity - Bones held together by dense, irregular CT Suture: bones held very tightly together by layer of dense, irregular CT; only found in the skull Stenosis: complete fusion of two bones into one e.g. frontal bones - Gomphosis: a ligament holding a tooth in jaw socket - Interosseous membranes (syndesmosis): between radius and ulna, tibia and fibula; greater distance between articulating surfaces Fibrous joints form strong connections between bones. (a) Sutures join most bones of the skull. (b) An interosseous membrane forms a syndesmosis between the radius and ulna bones of the forearm. (c) A gomphosis is a specialised fibrous joint that anchors a tooth to its socket in the jaw. Cartilaginous Joints - No joint cavity - Bones connected by hyaline cartilage or fibrocartilage - Synchondrosis: has hyaline cartilage e.g. epiphyseal plate - Symphysis: has a pad of fibrocartilage between the bones e.g. pubic symphysis and intervertebral discs Synovial Joints - Joint cavity/space between articulating bones - Joint held together by articular/joint capsule and ligaments - Joint cavity contains synovial fluid Components 1 - Joint/articular capsule (two layers): inner synovial membrane produces synovial fluid + outer fibrous layer continuous with periosteum encloses cavity Articular/hyaline cartilage: protects ends of bones during movement Synovial fluid: - Lubricates cartilage to reduce friction and shock - Supplies oxygen and nutrients to chondrocytes and removes wastes - Contains phagocytic cells to remove debris and microbes Ligaments: tough, resistant to strain; hold bones together in joint Components 2 Joint cavity: space for bones to articulate Meniscus: pads of fibrocartilage between articulating bones - Assists with shock absorption, weight distribution, and allowing better fit between articulating surfaces e.g. in knee Bursae: sacs with synovial membrane and fluid; resemble joint capsules - Positioned to reduce friction e.g. in shoulder and knee - Between bone and the skin, tendons, muscles or ligaments Functional Classification - Synarthrosis: an immovable joint i.e. suture and stenosis, synchondrosis - Amphiarthrosis: a slightly moveable joint i.e. interosseous membranes, syndesmosis and symphysis - Diarthrosis: freely moveable joint; have a variety of shapes and permit different types of movements e.g. elbow, hip Structural and Functional Categories Joint Movements - Extension and flexion are angular movements that increase (extension) or decrease (flexion) the angle between articulating bones. For example, when you bend at the elbow to lift a weight in a bicep curl (i.e., bring it towards your shoulder); this is flexion. The opposite movement to release the bicep curl is extension. - Abduction and adduction are angular movements away (abduction) or towards (adduction) the midline of the body. Both movements usually occur along the frontal plane. For example, when you lift your arm from beside your body to in line with your shoulder; this is abduction. Adduction is the opposite, returning your arm from in line with your shoulder towards the side of your body. - Circumduction is circular movement of the distal end of a body part. For example, moving the hand in a circle at the wrist joint. - Rotation is when a bone revolves around its own longitudinal axis. For example, when you shake your head 'no', you are rotating the head at the atlanto-axial joint. Functions of Muscular Tissue Storing and Moving Substances within the Body Protein reserves Sphincter muscles Controlling movement of substances Digestive system Cardiovascular system Urinary system Reproductive system Lymphatic system Stomach anatomy Soft Tissues Types of Muscle Tissue 1. Smooth Located in walls of hollow internal structure Blood vessels - changes diameter Stomach, intestine, bladder, uterus, airway to lungs Involuntary control Spontaneous rhythmic cycles (pacesetter cells) Influenced by hormones, stretching, ANS No tendons Smooth Muscle Histology - Uni-nucleated - Spindle shaped - Non-striated - Autorhythmic - Can divide - Can regenerate 2. Cardiac Only found in the heart Involuntary control Pacemaker cells (autorhythmic) Influenced by ANS and hormones Cardiac Muscle Histology Uni-nucleated Striated Branched Intercalated discs Myoglobin stores O 2 Cannot divide Cannot regenerate 3. Skeletal Most abundant muscle type in the body Voluntary control Controlled by nerves of the central nervous system Can be influenced by hormones Contraction = shortens muscle Relaxation = lengthens muscle Skeletal muscle can ONLY pull bone Skeletal Muscle Histology - Very long - Multinucleated - Cylindrical - Striated - Myoglobin stores - Cannot divide - Can repair Skeletal Muscle Organisation 1. Muscle - Organ 2. Fascicle - Functional unit in which muscle fibres work together 3. Fibre - Individual cells (myocytes) 4. Myofibril - Contractile fibres 5. Myofilaments - Thin filaments (actin) - Thick filaments (myosin) - Elastic filaments (titin) Skeletal Muscle Fibres - Aka myocytes - Sarcolemma - Sarcoplasm - Transverse tubules - Sarcoplasmic reticulum - sarcomere Myofibril Structure - Bundles of protein filaments (myofilaments) - Actin - Myosin - Titin - Myofilaments are responsible for muscle contraction - Sarcomere = contractile unit TOPIC 4A: MOVEMENT AND SUPPORT: MUSCULAR SYSTEM Skeletal Muscle Contraction Neuromuscular junction Contraction/relaxation How does Muscle Contraction Occur? Occurs at the level of myofibrils (contractile elements) During contraction and relaxation actin and myosin slide past each other Contraction is stimulated by the presence of calcium Requires adenosine triphosphate (ATP) as an energy source Summary: steps in muscle contraction/relaxation 1. ACh released in NMJ; binds to receptors 2. Action potential reaches T tubule 3. Sarcoplasmic reticulum releases Ca 2+ 4. Active site exposure; cross bridge formation 5. Contraction cycle begins 6. Ach broken down by AChe (acetylcholine esterase) 7. Sarcoplasmic reticulum recaptures Ca 2+ 8. Contraction ends 9. Relaxation occurs; passive return to resting length Muscle Tone Certain degree of contraction or undertone of contraction that occurs in muscles while at rest Allows us to maintain posture Stabilises bones and joints Ready response state events that occur during muscle contraction and relaxation: 1. Action potential spreads across sarcolemma. 2. Action potential reaches and travels down T-tubules. 3. Sarcoplasmic reticulum releases Ca2+. 4. Ca2+ binds to regulatory proteins on actin and exposes the active sites. 5. Myosin binds to active sites on actin forming cross-bridges. 6. Powered by ATP, repeated cycles of myosin pulling, pivoting, and detaching from actin occur. 7. Sarcomere shortens, muscle contracts. 8. Action potential stops arriving at the sarcolemma. 9. Ca2+ is reabsorbed into sarcoplasmic reticulum. 10. Active sites on actin become covered again, myosin detach from actin. 11. Contraction ends, and muscle relaxes. Muscle/Growth Regeneration Hypertrophy ^ use ^ of tissue size due ^ in size of cells e.g., skeletal muscle Hyperplasia ^ of tissue size due ^ in cell number e.g., smooth muscle Atrophy ↓ use ↓ in tissue size due ↓ in size of cells e.g., skeletal muscle WEEK 4 VOCAB - A cell that dissolves the fibers and matrix of the bone OSTEOCLAST - A cell that produces the fibers and matrix of the bone OSTEOBLAST - Membrane covering bone; essential for bone growth, repair and nutrition PERIOSTEUM - A freely movable joint where the opposing bone surfaces are separated by synovial fluid SYNOVIAL JOINT - An increase in the angle between two articulating bones EXTENSION - A movement that decreases the angle between two articulating bones FLEXION - A neurotransmitter that, when it binds to its receptor, initiates a muscle action potential ACETYLCHOLINE - Dense, fibrous cord of connective tissue that attaches muscle to bone TENDON - The functional junction between two neurons or between a neuron and an effector (e.g., muscle) SYNAPSE MODULE 5: TOPIC 5B: COMMUNICATION: ENDOCRINE SYSTEM The endocrine system coordinates functioning between different organs through hormones, which are released into the bloodstream from specific types of cells within endocrine (ductless) glands. Once in circulation, hormones affect function of the target tissues, which may be another endocrine gland or an end organ.” Endocrine: hormones - Secretion directly to the bloodstream - No ducts - E.g. insulin and glucagon Exocrine - Secretion onto epithelial surfaces - Via ducts - e.g., sweat, mucous, digestive enzymes Endocrine system: what does it do? Regulates growth and activity of target cells in the body Regulates growth Controls reproduction (inc. pregnancy and menopause) Regulates sleep Allows body to cope with stress, trauma and infection Regulates circulation and red blood cell production Controls digestion and absorption of food Regulates metabolism, water and electrolyte balance HOMEOSTASIS!!!! What is a hormone? - Blood-borne chemical messenger - Specific target - Low concentration Where are receptors located? - In the cell membrane - Cytoplasm - Nucleus Water soluble hormones - Cannot easily cross cell membrane - Interact with receptors on/in cell membrane - Effects are ‘indirect’ i.e., via second messenger systems - Most hormones (e.g., insulin, PTH, adrenaline) Fat-soluble hormones - Can easily cross cell membrane - Interact with receptors inside cell - Effects are ‘direct’ - e.g., cortisol, aldosterone, sex hormones, vitamin D, thyroid hormone Hormones: Mechanism of action Rates of enzymatic reaction - Change shape of enzyme; change function Controlling transport - open/close membrane channel Controlling gene expression - Turn on/off - Increase/decrease rate of protein production Role of the endocrine and nervous systems in maintaining homeostasis To preserve homeostasis, cellular activities must be coordinated throughout the body, but only a fraction of the cells in your body are innervated and commands from the nervous system are very specific and short-lived (i.e., measured in seconds). Given that many life processes (e.g., growth, development, and reproduction) occur over longer periods (hours to days to years), we need another means of control. This is where the endocrine system comes in. The activity of the endocrine system is coordinated with that of the nervous system to provide an integrated control of all body systems throughout our lifespan. Sends messages directly to effector (target) organs via nerves: NERVOUS Responses are quick but short-lasting: NERVOUS Messages are in the form of electrical impulses: NERVOUS Act on effector (target) organs to bring about change: BOTH Responses are slow, but longer in duration: ENDOCRINE Messages are in the form of chemical messengers BOTH Chemical messengers are hormones ENDOCRINE Chemical messengers used are neurotransmitters NERVOUS Sends messages indirectly to effector (target) organs via blood ENDOCRINE Responses aim to maintain homeostasis BOTH Chemical messenger must bind to a receptor on the target cell BOTH Uses adrenaline/noradrenaline as a chemical messenger BOTH Usually regulated via negative feedback mechanisms BOTH Hypothalamus-pituitary axis Anterior Pituitary - Makes and releases OWN hormones - Lots of hormones - Connection via capillary beds Posterior Pituitary - Stores and releases hormones made by the hypothalamus - Two hormones - Connection via nerve fibres Two hormones Oxytocin - Controls uterine contractions at the onset of labour - Controls milk release from lactating breast Anti-diuretic hormone - Acts on kidneys to reabsorb water - Regulates blood osmolarity - aka vasopressin Hypothalamus and Anterior Pituitary (thyroid gland) - Sensory inputs from the environment - Releasing (RH) and inhibiting (IH) hormones from the hypothalamus control the release of anterior pituitary hormones Two hormones: Thyroid Hormones - TH, T3, T4/thyroxine - Need iodine Calcitonin - ↓ blood calcium Thyroid hormone function Thyroid hormones affect almost all body cells - Increase basal metabolic rate - Increased metabolic rate means increased heat production - Stimulate protein synthesis and usage of fuels (to make ATP) - Enhanced sympathetic activity (e.g. ↑HR and ↑BP) - Essential for normal growth and development (especially skeletal and nervous systems) Regulation of thyroid secretion Hypothalamus and Adrenal Gland Essential for life Superior to kidney - Paired glands - Two regions - Cortex - medulla The hypothalamus controls adrenal glan function in 2 ways 1. Hormones secreted by the anterior lobe control other endocrine organs 2. Secretion of regulatory hormones to control activity of the anterior lobe of the pituitary gland. 3. Control of sympathetic output to adrenal medullae 4. Secretion of epinephrine and norepinephrine Adrenal cortex: Cortisol Adrenal medulla - control via innervation The adrenal medulla is a modified part of the SNS that secretes adrenaline and noradrenaline Metabolic effects - Increases amount of energy for immediate use: - Glycogenolysis – releases glucose - Lipolysis CVS effects - Increases cardiac output (↑heart rate and ↑stroke volume) - Vasodilation of coronary and skeletal muscle blood vessels - Bronchodilation - Vasoconstriction of blood vessels to ‘non-essential’ tissues (GIT, skin, kidneys) Glucose Homeostasis Why is it important - Our cells use glucose to produce ATP (energy) - Our cells use ATP to power important biological functions e.g., Protein synthesis e.g., Muscle contraction e.g., Nerve impulse transmission - The brain consumes LOTS of glucose derived energy How is glucose homeostasis regulated? Pancreas is key. Regulated by: 1. Insulin 2. Glucagon 3. Other hormones - Adrenaline, cortisol and growth hormone all act to increase BGL Hyperglycaemia Pancreas is key. After you eat: - Blood glucose increases - Insulin is released - Use - Store Hypoglycaemia Pancreas is key. When you are fasting: - Glood glucose decreases - Glucagon is released - Release stores - Make new glucose Calcium Homeostasis Why is calcium metabolism so carefully controlled? Calcium is important in many physiological processes - Structural component of bones and teeth (99% total calcium) - Maintains normal excitability of nerve and muscle cells - Muscle contraction (skeletal and cardiac) - Co-factor in many important reactions - Milk production Normal Calcium Balance How is Calcium Metabolism regulated? Parathyroid glands are key. Regulated by: 1. Parathyroid Hormone (PTH) 2. Vitamin D (calcitriol) 3. Calcitonin - Of minor significance in adult humans and more relevant in growing individuals Hypocalcaemia (increase blood calcium level) 1. Parathyroid glands release PTH 2. Osteoclasts release Ca2+ from bone 3. Calcium is reabsorbed from urine by the kidneys 4. Calcium absorption in the small intestine increases via vitamin D synthesis 5. Ca2+ levels in blood increase Hypercalcaemia (decrease blood calcium level) 1. Thyroid gland releases calcitonin 2. Osteoclast activity is inhibited 3. Ca2+ reabsorption in the kidneys decreases 4. Ca2+ level in blood decreases Function of Hormones TOPIC 1F: BASIC PROCESSES: GENETICS Genetics and Inheritance DNA = Deoxyribonucleic acid - Double-stranded helix - 4 bases Chromosome = 1 long DNA molecule DNA and nucleotides: - Phosphate group - Deoxyribose sugar - Nitrogen-containing base - Nucleotide pairs joined by hydrogen bonds Gene = unit of heredity - at specific location on a chromosome - code for a specific protein or enzyme to be made Allele = alternate DNA sequence version of a gene - Example: DNA sequence/code for brown eye colour pigment different than blue pigment sequence Autosome: chromosome pairs 1-22 - same in males and females Sex-chromosome: - chromosome pair 23 - XX in females - XY in males - 2 alleles per gene: 1 inherited from mum, 1 from dad Homozygous for a gene: the 2 alleles are identical Example: AATGCCATC AATGCCATC Heterozygous for a gene: the 2 alleles are different Example: ATTGCCGGT TTAGCCGGT Genotype: the two alleles for the gene - i.e. the genetic makeup e.g., Bb or BB Phenotype: outcome of the physical expression of the protein due to the allele(s) - i.e. the observable properties e.g., brown eye colour Types of Inheritance Dominant versus Recessive - When two alleles are different one may express the phenotype (dominant allele) thereby masking the expression of the recessive allele - To express a dominant trait only 1 dominant allele needs to be present (homozygous or heterozygous) - To express a recessive trait there must be 2 recessive alleles - Dominant allele is written as a capital letter; recessive allele with a lowercase letter e.g., B = dominant, b = recessive Autosomal Dominant Disease Example: - 50% of children inherit the dominant allele, N, therefore has neurofibromatosis type 1 - 50% inherit 2 normal alleles (nn) so are disease-free Codominance - Two alleles are dominant over a recessive allele - When both dominant alleles present, both phenotypes are expressed - Example human ABO blood groups - A and B alleles dominant over O - A blood group = AA or AO - B blood group = BB or BO - AB blood group = AB - O blood group = OO Sex-linked versus autosomal - When the disease allele is on the X chromosome it is sex-linked - Most X-linked diseases have recessive alleles - Males more commonly affected than females - X and Y chromosomes shown in genotype for sex-linked diseases Cell Division: Mitosis and Meiosis - Process by which cells reproduce themselves - Two types: Mitosis (replaces somatic/body cells) - Meiosis (forms gametes in ovaries and testes) Cell Cycle Two major phases of the cell cycle Mitosis: (cell division). Interphase: (cell grows and performs all its normal functions). DNA Replication Before ANY cell division the DNA must be replicated (copied) Replication of DNA occurs during the S phase of the cell cycle Mitosis Meiosis Mitosis vs Meiosis SEX CHROMOSOME Special pair of chromosomes that determin sex: X or Y chromosome in humans. GENOTYPE The genetic makeup of an organism. ALLELE Any of several forms of a gene, usually arising through mutation, that are responsible for hereditary variation GENE A portion of a DNA strand that functions as a hereditary unit, is located at a particular site on a specific chromsone, and codes for a specific protein or polypeptide. PHENOTYPE The physical appearance or observable traits of an organism. Often determined by the genetic makeup of an individual but environment can play a role. AUTOSOME Chromosome other than the X or Y chromosome. MUTATION A change in the nucleotide sequence of the DNA in a cell. These changes lead to variation between individuals which can be beneficial, deleterious (causes disease) or neutral (doesn't change the protein built). —----------------------------------------------------------------------------------------------------------------------- HETROZYGOTE An individual carrying two different alleles of a particular gene eg. Aa. AFFECTED ALLELE An allele or variant of a gene that will give rise to a disease phenotype. SEX-LINKED Relating to a gene carried on, or a trait transmitted by, a sex chromosome. RECESSIVE The ________ allele will not be expressed in a heterozygote, the individual must carry two copies of this allele to express the ________ phenotype. CARRIER A genetic __________ (or just _______), is a person or other organism that has inherited a recessive allele for a genetic trait or mutation but does not display that trait or show symptoms of the disease. DOMINANT The ________ allele will be expressed in a heterozygote ie. the individual will have the phenotype of that allele. HOMOZYGOTE An individual carrying two identical alleles of a particular gene eg. AA or aa. CO-DOMINANT Both allele's phenotypes will be expressed in a heterozygote individual. —--------------------------------------------------------------------------------------------------------------------- NEGATIVE FEEDBACK A corrective mechanism that opposes or negates a variation from normal limits ENDOCRINE Pertaining to hormones and the glands that make and secrete them into the bloodstream through which they travel to affect distant organs HORMONE A chemical that is secreted by one cell and travels through the bloodstream to affect the activities of cells in another part of the body RECEPTOR A cell protein that binds a specific hormone to elicit a physiological response in the target cell HYPOTHALAMUS Small region of the brain that is the major link between the nervous and endocrine systems —----------------------------------------------------------------------------------------------------------------------- DNA. Inherited genetic material inside each human cell DEOXYRIBONUCELIC ACID Threadlike strands of DNA and proteins found inside the nucleus, that serve to carry the genomic information from cell to cell CHROMOSOME DNA segment that is the biological unit of heredity. Located in a definite position on a particular chromosome GENE Alternate forms of a single gene that control the same inherited trait. Located in the same position on homologous chromosomes ALLELES The observable expression of a genotype; physical characteristics of an organism determined by genetic makeup and influenced by interaction between genes and internal and external environmental factors PHENOTYPE PREFIX/SUFFIX HOMO - same HETERO - different ZYG - joined together AUTO - self PHENO - show MODULE 6: TOPIC 6A: CARDIOVASCULAR SYSTEM: THE HEART The heart lies in the mediastinum, with about 2/3 of the heart mass lying to the left of the body's midline. The wall of the heart consists of three layers; the epicardium (external layer), myocardium (middle layer) and endocardium (inner layer). These are shown in the image below. Blood Flow Through the Heart 1 - Deoxygenated VENA CAVA 2 - Deoxygenated RIGHT ATRIUM 3 - Deoxygenated RIGHT ATRIOVENTICLE VALVE 4 - Deoxygenated RIGHT VENTRICLE 5 - Deoxygenated RIGHT SEMILUNAR VALVE 6 - Deoxygenated PULMONARY TRUNK 7 - Deoxygenated PULMONARY ARTERIES 8 - Deoxygenated/Oxygenated LUNGS 9 - Oxygenated PULMONARY VEINS 10 - Oxygenated LEFT ATRIUM 11 - Oxygenated LEFT ATRIOVENTRICULAR VALVE 12 - Oxygenated LEFT VENTRICLE 13 - Oxygenated LEFT SEMILUNAR VALVE 14 - Oxygenated AORTA 15 - Oxygenated PERIPHERAL CIRCULATION Heart DIagram - External Heart Diagram - Internal Conduction System of the Heart Cardiac Cycle Atrial systole Atrial diastole Ventricular systole Ventricular diastole Wiggler’s Diagram The phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood DIASTOLE The phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries SYSTOLE The simple squamous epithelium that lines the heart ENDOCARDIUM The cardiac muscle tissue of the heart MYOCARDIUM Blood vessels transporting blood from the left ventricle throughout the body and back to the right atrium SYSTEMIC CIRCULATION Blood vessels transporting blood from the right ventricle to the lungs and back to the left atria PULMONARY CIRCULATION The natural pacemaker of the heart; determines heart rate SINOATRIAL NODE —----------------------------------------------------------------------------------------------------------------------- cardi- or cardio - heart -gram - record brady - slow tachy - swift vas- or vaso - vessel —----------------------------------------------------------------------------------------------------------------------- MODULE 7: Blood Vessells TOPIC 7B: CARDIOVASCULAR SYSTEM: BLOOD VESSELS AND BLOOD PRESSURE Blood flows between the heart and peripheral tissues via a network of blood vessels. Arteries (efferent vessels) carry blood away from the heart, while veins (afferent vessels) carry blood toward the heart. Capillaries (exchange vessels) connect the smallest arteries (arterioles) and the smallest veins (venules). The thin wall of capillaries allows the exchange of nutrients, dissolved gases, and wastes between blood and interstitial fluid. The walls of arteries and veins contain three layers: 1. Tunica intima - this innermost layer is composed of an epithelial (endothelium) and connective tissue layer. The endothelium is continuous throughout the vascular system, including the lining of the chambers of the heart. In arteries, the outer margin of this layer contains a layer of elastic fibers called the internal elastic membrane. 2. Tunica media - this middle layer contains smooth muscle in a framework of loose connective tissue. When the smooth muscle contracts the vessel diameter decreases (vasoconstriction). When the smooth muscle relaxes the vessel diameter increases (vasodilation). In arteries, the outer margin of this later also contains a layer of elastic fibers called the external elastic membrane. 3. Tunica externa (tunica adventitia) - this outermost layer is a substantial sheath of connective tissue primarily composed of collagenous fibers, that typically bled into those of adjacent tissues, stabilising and anchoring the blood vessel. Comparison of Arteries and Veins VEINS ARTERIES - Thinner walls - Withstand higher pressure - Are low pressure - Lined with smooth muscle for - Experience low blood flow autonomic control - Have larger diameters - Help maintain pressure - Has valves to assist with returning - Have high elasti component for blood to the heart recoil - Experience high blood flow Blood Flow - Mean Arterial Pressure - Cardiac Output (HR X SV) - Total Peripheral Resistance - Vessel length - Vessel diameter - Vasoconstriction - Vasodilation - Blood Viscosity Capillary Exchange Capillaries are the smallest blood vessels in our body. Capillaries are microscopic and permeate most tissues in our body and, importantly, they are the ONLY blood vessels whose walls permit exchange between the blood and surrounding interstitial fluid. In this video, we will look at exchange of fluid between capillaries and our tissues, which is how oxygen and nutrients are moved into the interstitial fluid and wastes moved from the interstitial fluid into our capillaries. - Capillary hydrostatic pressure HPC - Interstitial fluid hydrostatic pressure HPif - Capillary colloid osmotic pressure OPc - Interstitial fluid colloid osmotic pressure OPif Baroreceptor Reflex The baroreceptor reflex allows us to quickly respond to changes in blood pressure. In this video, we will look at the series of actions that allows your baroreceptor reflex to quickly bring your blood pressure back to normal if your blood pressure raises or lowers. TOPIC 7C: CARDIOVASCULAR SYSTEM: BLOOD Components of Blood Erythrocytes Anucleated Biconcave discs Filled with haemoglobin (Hb) Haemoglobin Heme group bound to Globin protein Heme contains iron Fe2+ binds O2 Haemoglobin also binds CO2, but it is the globin proteins that bind it. Oxyhemoglobin Haemoglobin bound with oxygen Deoxyhemoglobin Haemoglobin without oxygen after oxygen diffuses into tissues (reduced Hb) Carbaminohaemoglobin Haemoglobin bound with carbon dioxide Leukocytes - Only complete cells in blood - ~1% of the total blood volume - Essential to immune system - Can leave capillaries via diapedesis - Move through tissue spaces Granulocytes - Phagocytic - Contain cytoplasmic vesicles (granules) - Stain differently - Acidic, Basic, or Both Neutrophils - Most abundant WBC Basophils - Release histamine Eosinophils - Counter parasitic worms Neutrophil - 50 – 70% of WBC - Multilobed nucleus - Granules stain both acid & basic - Peroxidases & hydrolytic enzymes - Defensins (antibiotic-like proteins) - Main bacteria killers Eosinophil - 2 – 4% of WBC - Bi-nucleated - Granules stain acidic - Digestive enzymes - Target parasitic worms Basophil - 0.5% of WBC - Bi-nucleated - Granules stain basic - Contain histamine - Release causes vasodilation and chemotaxis of other WBCs Agranulocytes - Do not have visible granules - May look similar – but are not! - Function is different - Nucleus shape - Spherical (lymphocytes) - Kidney-shaped (monocytes) Monocytes - 4 – 8% of WBC - Large U-shaped nucleus - Monocytes in blood – macrophages in tissue - Highly mobile & phagocytic - Activate lymphocytes Lymphocytes - ≤25% of WBCs - Large, dark nucleus - Two main types - T-cells – cellular immune response (virus-infected, tumour) - B-cells – plasma cells (antibodies) Natural killer - Part of the innate system - 2 – 18% of lymphocytes in peripheral blood - Detect MHC class I-deficient cells - Presence of MHC-class I on cells inhibits NK function Platelets - Megakaryocyte - Cytoplasmic fragments of this larger cell - Platelet granules contain: - Serotonin, Ca2+, enzymes, ADP, platelet- derived growth factor (PDGF) - Involved in the clotting mechanism Mast cell Reside in tissues - Boundaries between tissues and external environments Important role in inflammation - Activation causes release of inflammatory mediators Can be activated by a range of stimuli - allergens, pathogens, and physiological mediators Blood Groups Human blood groups - Glycoproteins on surface of RBCs - Unique to an individual - Recognized as foreign if transfused into another person - Promote agglutinatio - Antigens used to classify - Present or absent - Many groups (ABO, Rh, MNS, Dufy, Kell, Lewis) - Two main groups – ABO & Rh - Cause bad reactions if mismatched in transfusion - Foreign RBCs destroyed by host immune response ABO blood groups - Based around two antigens - A&B - A blood = A antigens on RBC - B blood = B antigens on RBC - AB blood = A & B antigens on RBC - O blood = Neither A nor B on RBC - Our plasma contains pre-formed antibodies recognizing A or B - No previous contact with antigen required Therefore: - A blood – anti-B - B blood – anti-A - AB blood – no anti-A or anti-B - O blood – both anti-A and anti-B Haemostasis - Series of reactions designed to stop bleeding - Three key phases – occur in rapid succession 1. Vascular spasms 2. Platelet plug formation 3. Coagulation (blood clotting) Vascular Spams Platelet Plug Formation Coagulation - A series of reactions which transforms blood from liquid to gel - Reinforcing the platelet plug - Coagulation initiated through two pathways - Intrinsic - Extrinsic - Both converge to a common pathway The final three steps of this series of reactions are: 1. Prothrombin activator is formed from both pathways 2. Prothrombin is activated into thrombin 3. Thrombin catalyses fibrinogen (soluble protein) into fibrin (insoluble protein) mesh. It traps blood cells and seals the hole Clot removal Clot retraction – first step - Platelets contract and pulls clot together - Brings edges of damage vessel together Repair – second step - Platelet derived growth factor (PDGF) stimulates rebuilding of blood vessel walls - Fibroblasts form a connective tissue patch - Stimulated by vascular endothelial growth factor (VEGF) endothelial cells multiply and restore lining Week 7 | Vocab, prefixes, suffixes A small blood vessel, located between an arteriole and a venule, whose thin walls permits the diffusion of gases, nutrients, and wastes between plasma and interstitial fluids CAPILLARY The resistance to blood flow, primarily caused by friction with the vessel walls PERIPHERAL RESISTANCE A protein arranged around an iron-containing haeme pigment that transports most of the oxygen, and some carbon dioxide, in blood HAEMOGLOBIN Anucleate fragments of cytoplasm enclosed in cell membranes. Circulate in blood and play an important role in haemostasis PLATELETS Stoppage of bleeding HAEMOSTASIS Liquid component of blood PLASMA Blood vessel carrying blood away from the heart ARTERY Blood vessel carrying blood towards the heart VEIN Determined by the presence and/or absence of certain genetically determined antigens on the surface your erythrocytes BLOOD TYPE —----------------------------------------------------------------------------------------------------------------------- a-or an - without baro - pressure -rrhage, rrhagic - to-burst-forth/bleeding haem -,haemo - blood thromb - clot MODULE 8:. TOPIC 6A: RESPIRATORY SYSTEM STRUCTURE AND FUNCTION Structure and Function Three major parts: Airways for ventilation Muscles for ventilation Alveoli for gas exchange Nasal Cavity, Nostrils and Sinuses: Function: Channel air into pharynx Warm, moisten and filter air Connected to olfactory bulbs Form: Mucous membranes Highly vascular Pharynx Function: Channel air into larynx Warm, moisten and filter air Form: Mucous membrane Highly vascular L-shaped bend Larynx Function: Channel air into trachea Modulate vocalisations Exclude solids and liquids from trachea Form: Cartilaginous chamber Rings of muscle (vocal cords) Glottis, epiglottis and laryngeal muscles Trachea Function: Channel air into lungs Form: Flexible tube ~12cm long Anterior to oesophagus The Lungs - Sacks containing airways and blood vessels - Entered via hilum - Divided into lobes by fissures - Right lung 3 lobes - Left lung 2 lobes due to cardiac notch Bronchial Tree Alevoli Alveolar sacs: Compose of multiple alveoli Bunch of grapes arrangement Alveoli: Individual grapes in bunch Thin film of liquid on inside Thin membrane with capillary network Defences Temperature and Moisture Vascular epithelium: - Warms cold air Mucous membranes: - Moisten dry air Nasal conchae: - Slow and disrupt airflow Particulates and pathogens Physical structures: - Nasal hairs - Nasal conchae - L-shaped bend in pharynx Mucous membranes: - Sticky trap Sneeze reflex - Triggered by irritation of nasal mucosa - By chemical or physical irritants or allergens - Expels irritants Mucociliary escalator - Goblet cells - Mucous membranes ciliated - Sweep debris toward pharynx - Cough expels debris from body - Debris swallowed Tonsils - In mucous membranes of pharynx - Five aggregations of lymphatic nodules - Detect and trap inhaled pathogens - Flush them via lymph system Trachea form - Epiglottis in larynx should exclude solids, but... - Trachea held open by C-shaped cartilaginous rings - Gap in rings contains trachealis muscle - Can expand to prevent blockages Alveolar macrophages - Phagocytic cells in alveoli walls - Destroy particulates + pathogens - Also called dust cells TOPIC 6B: VENTILATION What is pressure Pressure is the force exerted on a container by its contents Pressure gradients Movement from area of higher pressure to area of lower pressure - Down the pressure gradient Movement stops when pressures are equal - No pressure gradient The Process of Ventilation The Pleura Inhalation - External intercostal muscles pull ribs out and up (~25% of normal breath) - Diaphragm pulls down ~1cm (~75% of normal breath) - Intrapleural cavity expands - Air pressure in cavity drops (same volume of gas in larger space) - Pressure gradient created - lungs > intrapleural cavity - Lungs expand - Air pressure in lungs drops (same volume of gas in larger space) - Pressure gradient created - atmosphere > lungs - - Air inhaled into lungs - Air pressure in lungs rises (greater volume of gas in same space) - Pressure gradient equalised - lungs = atmosphere Exhalation - External intercostal muscles relax & ribs return to normal - Diaphragm relaxes & returns to normal position - Intrapleural cavity constricts - Air pressure in cavity rises (same volume of gas in smaller space) - Pressure gradient created - intrapleural cavity > lungs - Air exhaled from lungs - Air pressure in lungs drops (smaller volume of gas in same space) - Pressure gradient equalised - lungs = atmosphere Measuring Respiration and Ventilation Respiration rate: - Number of breaths per minute (bpm) - Normally 12-20 in healthy adult Ventilation rate: - Volume moved with each inhalation or exhalation × breaths per minute - E.g., 500ml × 20 breaths per minute = 10 litres per minute What is forced breathing for? - When oxygen requirements are higher than normal - Extra muscles engaged during inhalation to expand the ribs more than usual - Extra muscles engaged during exhalation to contract the ribs more than usual - Active processes (use energy to drive muscles) Surface Tension in the Alveoli - Surface tension of water makes alveoli collapse after exhalation - Reinflation of alveoli difficult - Surfactant reduces surface tension of water - Makes inhalation easier - Lack of surfactant makes breathing difficult Airway Resistance - Airflow through airways driven by pressure gradients - Slowed by resistance (friction against walls of airways) - Airways surrounded by smooth muscle - Broncho-constriction and -dilation alter resistance - Constrictive lung diseases increase airway resistance – make inhalation difficult Lung Muscles TOPIC 6C: GAS EXCHANGE AND CELLULAR RESPIRATION Gas Exchange Partial Pressures/Gradients Atmospheric Composition Types of Gas Exchange 1. Internal Respiration 2. External Respiration Conducting zone - Passage for moving air into and out of lungs - Not involved in gas exchange - Nasal cavity + pharynx + larynx + trachea + bronchi + bronchioles + terminal bronchioles Respiratory zone - Surfaces involved in gas exchange Anatomical dead space Volume of air in conducting zone (not involved in gas transfer) ~150ml in adult male Physiologic dead space - Anatomic dead space + alveolar dead space - Alveolar dead space = volume of air in respiratory zone not involved in gas transfer - Alveolar dead space usually negligible in healthy person Alveolar ventilation - Separate from ve

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