Biomedicine: Human Sciences - Cytology, Basic Genetics PDF

Welcome to Biomedicine: Human Sciences The College of Naturopathic Medicine (CNM) © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 1 Biomedicine: Human Sciences Lecture 1: Cytology, Basic Genetics and H...

Welcome to Biomedicine: Human Sciences The College of Naturopathic Medicine (CNM) © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 1 Biomedicine: Human Sciences Lecture 1: Cytology, Basic Genetics and Histology © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 2  Learning Outcomes In today’s topic you will learn:  The characteristics of life.  Homeostasis, positive and negative feedback systems.  Different types of cells and cell organelles.  Genetics: DNA, RNA, gene structure, function and inheritance.  The two types of cell division.  Understanding protein synthesis.  Movement of substances.  Types of tissues in the human body. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 3  Biomedicine Anatomy: Study of the structures that form the body. Physiology: How the parts of the body work. Pathology: Study of abnormalities from normal function. anatomy = Greek for ‘cutting up' (like in a dissection) physio- = Greek for ‘nature / natural’ patho- = Greek for ‘suffering’ or ‘disease’ -ology = Greek for ‘study of’ © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 4  Characteristics of Life Metabolism: Sum of all the chemical processes in the body. Responsiveness: Ability to respond to changes in the environment. Movement: Movement of the whole organism or of individual organs, cells and structures inside cells. Reproduction: Formation of new cells or production of a new individual. Growth: Increase in size or increase in number. Differentiation: Development to specialised state. Vital Force / Life Force / Qi. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 5  Characteristics of Death Loss of heartbeat. Absence of breathing. Loss of brain function. No Vital Force / Life Force / Qi. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 6  Homeostasis homeo- = Homeostasis is a fundamental principle of ‘of the same kind’ physiology. stasis = still The condition of equilibrium (balance) in the body’s internal environment maintained by the body’s own regulatory processes. It is dynamic and ever-changing whilst always remaining within certain narrow limits to ensure optimal functioning of all life processes. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 7  Homeostasis The following physiological variables must be kept pH scale: within narrow parameters (homeostatic balance) in 14 the body: 1. Core temperature (36.5-37.5°C). 2. Water and electrolyte concentrations. 3. pH (acidity or alkalinity) of body fluids. 4. Blood glucose levels. 5. Blood and tissue O2 / CO2 levels. 6. Blood pressure. 0 7. Flow of Life Force. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 8  Homeostasis An important aspect of homeostasis is the maintenance of body-fluid composition and volume. Body fluids are either intracellular or extracellular (e.g. blood plasma, synovial fluid, lymph fluid, interstitial fluid). intra = inside Proper functioning of body cells relies on extra = outside cellular = cell interstitial fluid composition. It changes synovial fluid = a lubricating as substances move back and forth fluid found in many joints inter- = between (cells) between it and the blood. -stitial = positioned © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 9  Homeostatic Control Homeostasis is constantly being disturbed by external and internal factors and so requires control systems to bring it back into balance. These control systems are made up of: 1. Disruptors: Change homeostatic parameter. 2. Detectors: Receptors that detect disruption (often nerves). 3. Control centre: Determines limits within which parameters should be maintained. Evaluates input and generates output. 4. Effectors: Structures that receive output. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 10  A feedback system is a group of receptors and effectors communicating with their control centre. Negative feedback: Positive feedback: The output reverses the Strengthens change in input. one of the body’s controlled conditions © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 11  Negative Feedback System The output reverses the input. Accounts for most body variables. The effector response decreases the effect of the original stimulus, maintaining or restoring homeostasis. Works like a central heating system. Negative feedback examples include: Increasing or decreasing body temperature, blood glucose, blood pressure. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 12  Positive Feedback System Tends to strengthen / reinforce change in one of the body’s controlled conditions (‘amplifier’). Like negative feedback, it still provides commands to an effector. However, this time it works to reinforce (fairly rare in the body). Stimulus progressively increases the response — as long as the stimulus is continued. Examples include: Childbirth, milk production, enzyme reactions, immunity, blood clotting. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 13  Body Organisation Atoms and molecules: Chemical level. Cells: The smallest living units in the body. Tissues: Groups of cells that work together to perform a function. Organs: Groups of tissues working together. Systems: Related organs that have a common function. The organism: All body parts together. Vital Force: The energy that creates life. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 14  Systems of the Human Body Skeletal system Muscular system Respiratory system Cardiovascular system Digestive system Endocrine system Lymphatic system Integumentary system Urinary system Reproductive system Nervous system Immune system Life / Vital Force influences all body systems. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 15  Body Cavities The body’s organs are primarily located within four cavities: 1. Cranial. 2. Thoracic. 3. Abdominal. 4. Pelvic. The diaphragm is the main muscle of breathing. It differentiates the thoracic cavity (above it) from the abdominal cavity (below it). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 16  The Cell Theory cyto- = cell (‘hollow vessel’) All known living things are made up -ology = a field of study of cells and Vital Force. The cell theory The cell is the structural and functional was proposed unit of all living things. in 1839. All cells come from pre-existing cells by cell division. Cells contain hereditary information in the form of DNA, which is passed on from cell to cell during cell division. All energy flow of life (metabolism and Life Force) occurs within cells. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 17  Cell Memory We typically think of the brain as being the main structure to store memory in the body. However, memories can be stored outside the brain in individual body cells. Cell memory describes the ability of cells to remember experiences which influence the Vital Force in our cells and body. Traumatic experiences and even negative beliefs may be stored as a negative charge of energy in cells. Vital Force is free-flowing throughout the body in a healthy person, but can become blocked creating the possibility for disease. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 18  Disease A disruption of body physiology can cause disease. Cells are interconnected making up organs and systems through their energy flow. When this is disrupted, diseases manifest in these organs. Stagnation of energy can be caused by many factors such as dietary choices, lifestyle influences, drugs and exposure to harmful substances, such as radiation. Healing involves correcting energy blockages, promoting self-healing. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 19  Metal Toxicity and Cell Damage Heavy metals such as aluminium, mercury and lead can accumulate in the body and cause damage to cells. Aluminium toxicity has been significantly linked to disorders such as Alzheimer’s. It can cause damage to neurons in the brain and is also a risk factor for cancers such as breast cancer. Aluminium is widely abundant — it is used to make foil, kitchen pans, anti-perspirants, and is also a key ingredient of vaccine. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 20  cyto- = cells Cells and Oxidative Stress toxic = poison Oxidative damage (damage of a structure by a molecule containing oxygen) often occurs due to toxins, stress, smoking, diets rich in refined sugars and processed foods, etc. The oxygen molecules that can cause oxidative damage are also known as free radicals. Free radicals are unstable and highly-reactive molecules. They lack an electron in their atomic structure, which can be donated by antioxidants. Antioxidants include vitamin C, E and beta-carotene. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 21  Cells and Oxidative Stress Oxidative damage influences key cell structures and even causes genetic mutation — this occurs during the development of cancer. Cell membranes can be damaged by toxic metals such as mercury (e.g. in dental filings, some vaccines), aluminium and lead. It is essential to consider the balance between free radicals and antioxidants in patients. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 22  Prokaryotic and Eukaryotic Cells Prokaryotic cell: Cells are either classified Eukaryotic cell: as being prokaryotic or eukaryotic. Prokaryotic cells contain no nucleus, and no membrane binds internal cell structures. Eukaryotic cells contain a nucleus and membrane- eukaryotes: with nucleus bound organelles. prokaryotes: without nucleus © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 23  Please refer to your DNA = deoxyribonucleic acid Glossary and Prefixes and Suffixes Cells RNA = ribonucleic acid Characteristic: Prokaryote: Eukaryote: Nucleus: No nucleus (DNA / RNA Membrane-bound located in cytoplasm). nucleus. Relative size: Far smaller. Bigger. Membrane-bound Absent. Many present. organelles: Cell wall: Present. Only in plants / fungi. Cell division: Binary fission (rapid mitosis). Involves mitosis. Includes: Bacteria. Human / animal cells. Plants / fungi. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 24  Cell Components Cell wall: Internally, cells consist of: Human cells do NOT Cytosol: Basic watery have a cell wall (only fluid inside a cell. a cell membrane). Organelles: Small Plant, fungal and specialised structures within the cell, e.g. bacterial cells have organ- = the Greek ribosomes produce cell walls. proteins. ‘organon’ meaning Cell walls provide instrument / tool Cytoplasm: Cell content strength and rigidity to organelles = specialised excluding the nucleus cells and surround the structures within a (includes the cytosol and cell membrane. living cell. organelles). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 25  phospho- = phosphate Cell Membrane lipid = fat bilayer = double layer The cell membrane is a flexible, semi- permeable membrane that separates the cell’s external and internal environment. Structurally, it is a phospholipid bilayer. This arrangement occurs because lipids are hydrophobic (water-hating — tails on the inside) and the phosphate heads are hydrophilic (water-loving — on outside). trans- = across The membrane is embedded with transmembrane proteins. The membrane controls substance movement in and out of cells. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 26  Cell Membrane The cell membrane is a fluid structure, which allows mobility and assists in cell processes such as growth, movement and secretion. Transmembrane proteins perform the following: 1. Transport of substances in / out of cells: This includes the movement of charged particles, e.g. hydrogen (H+) and larger molecules, e.g. glucose. 2. Immunological identity: Helps our immune cells recognise our own cells (this stops our white ion = a molecule with blood cells from attacking our body cells). an electric charge, e.g. hydrogen, sodium, potassium 3. Receptors: Recognition sites for hormones, etc. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 27  Phospholipid Bilayer Lipid tails The hydrophobic lipid (green) tails face inwards whilst the hydrophilic phosphate heads face outwards. The membrane is also Phosphate heads (purple spheres) embedded with Autoimmune diseases (e.g. coeliac transmembrane disease) occurs when white blood cells proteins and other fats target our own cell membrane proteins. such as cholesterol. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 28  Cell Junctions Cell junctions are contact / communication points between the adjacent cell membranes of tightly-packed cells. These include: 1. Tight junctions: Found in the stomach, intestines and bladder. Transmembrane proteins fuse cells together to reinforce the junctions and seal off passageways (prevents leaking). 2. Gap junctions: Small fluid-filled tunnels between neighbouring cells, e.g. nerves. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 29  Organelles The following are key organelles found in body cells: Nucleus (and nucleolus) Mitochondria Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes Cytoskeleton © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 30  Organelles: Nucleus The nucleus is a spherical structure that contains the body’s genetic information in the form of DNA. All body cells have a nucleus, with the exception of red blood cells. These lose their DNA (deoxyribonucleic acid) nucleus during development to maximise the = a self-replicating material present in living organisms space available to carry oxygen in the blood. as the main constituent of chromosomes, carrying The nucleus controls all cell functions, hence genetic information. RNA (ribonucleic acid) = is the brain of the cell. It contains a essential for protein nucleolus which produces RNA. synthesis. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 31  Organelles: Nucleus The nucleus is surrounded by a double-layered nuclear membrane which separates the nucleus from the cytoplasm. The membrane is continuous with the rough endoplasmic reticulum. The nuclear membrane contains nuclear pores for substance movement in and out of the nucleus. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 32  Organelles: Cytoskeleton The cytoskeleton is a network of protein filaments (microtubules and microfilaments) that extends through the cytosol. These protein filaments assist in the following: 1. Generate cell movement — e.g. enable white blood cells to migrate to sites of injury. In muscle cells, they are the organelles that enable muscle contraction. 2. Physical support and shape — they determine the cell shape. 3. Cell division — they move chromosomes apart. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 33  Organelles: Mitochondria Mitochondria are the second-largest organelle and are bean-shaped. Mitochondria are the cell powerhouses because they generate ATP (adenosine triphosphate). ATP is the energy currency of body cells. They are located near where oxygen enters cells (e.g. towards periphery / outside), or where ATP is used in the cell. They contain a double-layered membrane with fluid in between. The inner membrane has a series of folds called cristae which produce a vast surface area for reactions to take place. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 34  Organelles: Mitochondria Cells can contain one hundred to several Mitochondria thousand mitochondria, depending on the cell. under microscopy: Muscle cells (including those in the heart) are thought to contain the most mitochondria. They use ATP to generate muscle contraction. Mitochondria use oxygen and nutrients such as glucose to create ATP in a process called aerobic respiration (see equation below). (Glucose) + oxygen  carbon dioxide + water + ATP © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 35  Organelles: Ribosomes Ribosomes act as the sites of protein There are synthesis. Their name reflects the high thousands of content of ribonucleic acid (RNA). ribosomes per cell (25% of cell mass) Ribosomes are either free (mobile) in cytoplasm or bound to rough endoplasmic reticulum (stationary). Free ribosomes make protein for inside the cell, whilst those on the rough endoplasmic reticulum make protein for outside the cell. They synthesise proteins for specific organelles, which they export from the cell, e.g. hormones. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 36  Organelles: Endoplasmic Reticulum (ER) The endoplasmic reticulum (ER) is endoplasmic = within plasma a network of membranes in the form reticulum = network of flattened sacs. The ER extends from the nuclear envelope throughout the cytoplasm, to the cell membrane. Rough ER: Continuous with nuclear membrane. Its outer surface is studded with ribosomes (hence rough appearance).  Synthesises and transports proteins. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 37  Organelles: Smooth ER Smooth ER: The smooth ER contains no ribosomes, hence the smooth appearance. It contains unique enzymes and performs the following:  Synthesises lipids and steroid hormones, e.g. oestrogen.  In the liver, enzymes of smooth ER detoxify alcohol and drugs.  In muscle, it releases calcium for muscle contraction. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 38  Organelles: Golgi Apparatus The Cell Post Office The Golgi apparatus modifies, sorts, packages and transports proteins received from the rough ER. It consists of flattened membranous sacs. Most cells have several Golgi apparatuses. A transport vesicle that buds off from the rough ER moves towards the Golgi apparatus and releases proteins into it. Enzymes modify the proteins and they bud off in transport vesicles. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 39  lyso- = breakdown Organelles: Lysosomes soma = body Lysosomes are vesicles that perform a key role in cell digestion. Contain as many as 60 powerful enzymes, which can break down a variety of molecules once fused with them. Lysosomes recycle worn-out organelles; they engulf and digest these and the components are returned to the cytosol for re-use. They are also used to digest foreign cells. Lysosomes also release enzymes externally, such as with sperm to assist egg entry. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 40  Chromosomes There are six feet of DNA per human cell Chromosomes are thread-like structures of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. Each cell in the body (except sex cells, i.e. sperm / eggs) contains 46 chromosomes (or 23 pairs). Normal body cells are called somatic cells, whilst sex cells are called gametes. The hereditary units called genes are arranged along chromosomes. Chromosomes are formed of DNA that has coiled up. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 41  Chromosomes DNA forms a double helix which coils around proteins called histone. DNA is organised into a mass of compact, string-like fibres called chromatin. Just before cellular division, the chromatin condenses even further and is subdivided into 46 individual molecules called chromosomes. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 42  Chromosomes Chromosome set: X and Y chromosomes: The 23rd pair of chromosomes controls the inheritance of sex: In males, the two sex chromosomes are different = XY In females, the two sex chromosomes are the same = XX Therefore, if there is a genetic disease on the single X chromosome, the Y cannot counteract it; this may lead to sex-linked, genetic diseases in males. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 43  Genes Genes are sub-sections of DNA that act as instructions to make proteins. They are located along chromosomes — there are thousands per chromosome. A gene holds the information to build and maintain cells and pass genetic traits to offspring. All body cells (somatic cells) contain the full genome (full set of genes). One gene codes for the production of one protein. Only certain genes are working depending on the cell’s job — only certain genes are switched on. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 44  Protein Synthesis Cells use the DNA code as a template synthesis = production for the synthesis of a specific protein. mRNA = messenger RNA poly = many Proteins can be used by cells, whilst others peptide = protein are hormones, antibodies, enzymes, etc. Gene Protein synthesis includes two phases: 1. Transcription: A copy of one gene is made into mRNA. This travels out of the nucleus to a ribosome. 2. Translation: The ribosome reads the code and produces a chain of amino acids to form the required protein. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 45  Mutation A mutation describes a change in the genetic information (DNA sequence). DNA consists of various sequences of four nucleotides (A, T, C, G). A mutation changes this sequence through different mechanisms. ATCG are the four Mutations in gametes (sex cells) are nucleotide base passed on to offspring. Mutations in pairs found in DNA somatic cells cannot be inherited. Nucleobases: Adenine (A) Thymine (T) Mutations can occur by chance or be induced Cytosine (C) by mutagenic agents, e.g. radiation, smoking, Guanine (G) vaccines. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 46  Video and Summary Quiz: 1) Define the term homeostasis. 2) Briefly explain how a negative feedback system works. 3) Describe the structure of the cell membrane. 4) Describe TWO functions of the cell membrane. 5) What is meant by the term hydrophilic? 6) How many chromosomes does a human somatic cell have? 7) Describe the main function of ribosomes. 8) Name the cell organelle involved in energy (ATP) production. 9) Name the cell organelle that modifies, sorts and packages proteins. 10) State ONE function of lysosomes. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 47  Cell Reproduction: Mitosis Somatic cells reproduce via mitosis to mito- = Greek for ‘thread’ -osis = process create two cells identical to the original mother cell. Mitosis is used for growth and repair. A full set of chromosomes is first duplicated and then evenly distributed into both daughter cells. The chromosomes are split (pulled apart) by the protein filaments that make up the cytoskeleton. One division creating two identical daughter cells. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 48  Rates of Mitosis The following cells and organs replace themselves as follows: The outer layer of skin (epidermis) — every 40 days. Stomach and intestines (superficial lining / mucosa) — every five days. Liver (can regenerate entirely from a quarter of its tissue) — five months. Red blood cells — every 90-120 days. Taste buds — every 10 days. However, some cells in the body cannot undergo mitosis; e.g. the specialised nerve cells called ‘neurons’. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 49  Cell Reproduction: Meiosis Meiosis describes the process through which meiosis: from Greek gametes (sex cells) are formed. meaning ‘to reduce or diminish’ Produces four haploid cells through two divisions. The four cells produced are non- identical as the chromosomes overlap (hence genetic variability). All gametes have a haploid nucleus, which means they contain 23 chromosomes. All somatic cells (body cells) have a diploid (2n)= 46 chromosomes. haploid (n) = 23 chromosomes diploid nucleus (46 chromosomes). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 50  Cell Reproduction: Meiosis Gametes (sex cells) are haploid cells (23 chromosomes). A female gamete (ovum) is larger and immobile, whilst a male gamete (sperm) is smaller and mobile (due to its tail / flagellum). Fertilisation (conception) describes the fusion of a male and a female gamete. This leads to the formation of a zygote (a diploid cell) which has two copies of each chromosome (23 pairs) — one from each parent. The zygote then undergoes mitosis and develops into an embryo and finally a foetus (after eight weeks). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 51  Cellular Reproduction © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 52  Transport of Molecules Substances can move in and out of cells through the cell membrane. Transport of materials across the cell membrane is essential to cell life. Certain substances must move into the cell to support various functions such as metabolism and immunity, whilst substances must also be excreted from the cell. The two main types of movement that occur are passive and active transport. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 53  Passive Transport Passive transport describes the movement of substances from an area of high to low concentration (down the concentration gradient). Passive transport requires NO energy. The three types of passive transport are: 1. Diffusion — the movement of small substances from a high to low concentration. 2. Osmosis — the passive movement of water. 3. Facilitated diffusion — the movement of larger substances from high to low concentration facilitate = to assist with the aid of transmembrane proteins. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 54  Passive Transport Osmosis: Facilitated diffusion: Diffusion: Movement down the concentration gradient aided by Movement of small Movement of water down transmembrane molecules down the concentration gradient. proteins. For larger the concentration Water dilutes concentrated substances such gradient, such as solutions and concentrates as glucose and gases, e.g. oxygen. diluted solutions. charged molecules. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 55  Active Transport Active transport describes the movement of substances from an area of low to high concentration (up the conc. gradient). Active transport requires energy (ATP). The main examples of active transport are: 1. Pumps (e.g. sodium-potassium pump) — use protein pumps in the cell membrane to allow specific molecules up the concentration gradient. 2. Endocytosis — engulfing of particles into the cell through cell membrane extensions. 3. Exocytosis — removal of waste from the cell. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 56  phago- = to eat Active Transport pino- = to drink (from Greek) Pump e.g. H+ pump: Endocytosis: Exocytosis: Movement of molecules up the Particles are Removal of waste concentration gradient engulfed by the cell. from the cell. using a protein pump. Phagocytosis: ‘Cell- The material Used for H+ , K+, Na+ eating’ (solids). fuses with the cell The Na+-K+ pump is Pinocytosis: ‘Cell- membrane before important for nerves. drinking’ (liquids). being expelled. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 57  epi- = covering Histology -thelial = layer of cells A tissue is a group of specialised cells with a similar function. The four types of tissue are: i. Epithelial tissue — covers parts of the body. Cells are closely packed together; e.g. epidermis (skin), digestive tract lining, lungs, heart, etc. ii. Connective tissue — most abundant tissue, including bone, cartilage and blood. iii. Muscular tissue — contracts to create movement. iv. Nervous tissue — transmits electrical signals round the body. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 58  epi = on top Epithelial Tissue -thelial = layer of cells Epithelial tissue is covering / lining tissue. Consists of closely-packed cells arranged in continuous sheets, in single or multiple layers. Divided into covering and glandular epithelium. Epithelial tissue provides a selective barrier, for protection and secretion of substances. Epithelial tissue is located in blood vessels, the heart, lungs, reproductive organs, urinary tract, gastrointestinal tract (GIT), skin, eyes. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 59  Epithelial Tissue: Glands A gland is a single cell or groups of epithelial cells that produce secretions. There are two types: Exocrine glands: Secrete their products into ducts. Secretions include saliva, milk, sebum, sweat, enzymes. Endocrine glands: Enter interstitial fluid and then diffuse into blood. These glands produce hormones. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 60  extra = outside Connective Tissue cellular = cell Connective tissue is the most diverse and abundant kind of tissue in the body. Most connective tissues provide a supportive function (bone and cartilage), whilst other types are fluid (blood). Connective tissues are formed of two basic elements: Extracellular matrix. Cells (that are widely spaced apart). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 61  Connective Tissue 1. Extracellular matrix: Formed of ground substance and protein fibres. - Ground substance is between cells and helps determine the functionality of the tissue (fluid, semi-fluid or calcified). Contains water, hyaluronic acid and chondroitin sulphate. Fibres are collagen and elastic. 2. Cells: The cells are widely spaced unlike epithelium. - These include cells that synthesise the protein fibres, white blood cells and fat cells. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 62  Connective Tissue Cells in connective tissue are widely spaced apart. The distribution of cells is different to the packed cell structure seen in epithelial tissues. The spaces between cells are called the extracellular matrix and contain the ground substance and protein fibres. Protein fibres are produced by fibroblasts. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 63  Connective Tissue: Fibres Collagen and elastic fibres are found within the matrix of connective tissue. They are produced by fibroblasts. Collagen fibres: Elastic fibres: Made from the protein Made from the protein collagen. elastin, surrounded by glycoprotein to add strength. Strong fibres. Smaller diameter. Especially in bone, Strong but stretchy. Allow ligaments, tendons. tissue to return to original shape. Occur in parallel bundles In skin, blood vessel walls, for extra strength. and lung tissue. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 64  adipo = fat Connective Tissue: Cells cyte = cell 1. Fibroblasts: Large and most numerous cells. Secrete protein fibres to make collagen and elastic fibres. Active in repair and healing. 2. Adipocytes: Store triglycerides (fat). 3. White blood cells: Macrophages  engulf foreign cells (phagocytes). Lymphocytes  produce antibodies. Mast cells  release inflammatory chemicals. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 65  Connective Tissue Functions 1. Structural framework (bone, cartilage). 2. Transport nutrients and wastes (blood). 3. Protection for vital organs (bone, cartilage, adipose). 4. Support and interconnection (tendons, ligaments, etc.). 5. Insulation (adipose tissue). 6. Energy store. 7. Production of blood and lymphatic cells (adipose tissue, bone marrow). 8. Defence and repair (blood, lymph). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 66  Connective Tissue Summary Connective tissue Extracellular Cells Adipocytes: matrix Fat storage Ground Fibres: Leukocytes: Fibroblasts: substance Collagen Macrophages Produce / elastin Lymphocytes collagen and Mast cells elastic fibres © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 67  Membranes Membranes in the body combine epithelial and connective tissues. Membranes are flat sheets that cover or line areas of the body. The four types of membranes in the body are: 1. Cutaneous membrane (the skin). 2. Mucous membrane. synovial = a lubricating fluid in many joints cutaneous = from Latin ‘cutis’ meaning skin 3. Serous membrane. mucus = a secretion lining mucous membranes 4. Synovial membrane. serous from ‘serum’ = a thin watery fluid © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 68  Mucous Membranes Mucous membranes line hollow organs that open to a surface of the body. Mucous membranes line the entire digestive, respiratory and genito-urinary tracts. In the digestive system, the membranes secrete enzymes needed for digestion and also act as the sites for absorption. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 69  Mucous Membranes The epithelial layer contains goblet cells that produce and secrete mucus — a slimy fluid, which: 1. Protects the lining membrane from mechanical and chemical injury / drying (e.g. in the stomach). 2. Traps foreign particles in the respiratory tract (before they are removed by microscopic hairs called cilia). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 70  serous = watery Serous Membranes secretion Serous membranes line body cavities parietal = walls of a cavity that do not open to the exterior. visceral = referring to organs Serous membranes are double-layered, containing an: 1. Inner visceral layer — surrounds organs. 2. Outer parietal layer — lines a cavity. Between the visceral and parietal layers lies serous fluid. Serous fluid enables an organ to glide freely within the cavity without friction. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 71  Serous Membranes The three serous membranes in the body are: 1. Pericardium: Surrounding the heart. 2. Pleura: Lining the thoracic cavity and surrounding the lungs. 3. Peritoneum: Lining the abdominal cavity and surrounding abdominal organs (and some pelvic organs). © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 72  Synovial Membranes -cyte = cell Synovial membranes line cavities of freely- movable joints in the body. The membranes contain cells called synoviocytes, which secrete synovial fluid. Synovial fluid lubricates and nourishes the moveable joint cavities which it bathes. Synovial membranes also surround tendons that could be injured by rubbing against bones, e.g. over the wrist joint. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 73  Summary Quiz: 1. Briefly describe what the process of mitosis produces. 2. Meiosis is a process that produces what type of cells? 3. Define the term mutation. 4. State TWO major differences between passive and active transport. 5. What is moving during osmosis? 6. Name the type of gland that secretes its products into ducts. 7. Name TWO protein fibres found in connective tissue. 8. Name TWO body systems where mucous membranes exist. 9. Name the serous membrane surrounding the lungs. 10.Explain the role of goblet cells. © CNM: Human Sciences – Cytology, Basic Genetics and Histology. BQ/MC 74