Endeavour College of Natural Health endeavour.edu.au

Endeavour College of Natural Health endeavour.edu.au

BIOH122 Human Biological Science 2 Session 8 Immune System 1 Bioscience Department Endeavour College of Natural Health endeavour.edu.au

Session Plan o Immune system: Overview o Innate Immunity: Non specific resistance Second line of defence Phagocytosis Inflammation o Adaptive (Specific) Immunity Overview Endeavour College of Natural Health endeavour.edu.au 3

The Second Line of Defense Endeavour College of Natural Health endeavour.edu.au 4

Second Line of Defense: Internal Defenses o The second line of defence: Internal defences provided by Antimicrobial substances Natural killer cells Phagocytes Inflammation Fever Endeavour College of Natural Health endeavour.edu.au 5

Antimicrobial Substances o Antimicrobial substances that discourage microbial growth: Interferons Complement system Iron-binding proteins Antimicrobial proteins Endeavour College of Natural Health endeavour.edu.au 6

Antimicrobial Substances o Interferons (IFNs): Produced by lymphocytes, macrophages, and fibroblasts infected with viruses. Interfere and stop viral replication. o Complement system: A group of about 30 inactive proteins present in blood plasma and on plasma membranes when activated, these proteins complement or enhance certain immune, allergic, and inflammatory reactions. Endeavour College of Natural Health endeavour.edu.au 7

Antimicrobial Substances o Iron-binding proteins: Inhibit growth of certain bacteria by reducing amount of available iron. o Examples: Transferrin: in blood and tissue fluids Lactoferrin: in milk, saliva, and mucus Ferritin: in the liver, spleen, and red bone marrow Haemoglobin: in red blood cells Endeavour College of Natural Health endeavour.edu.au 8

Antimicrobial Substances o Antimicrobial proteins (AMPs): Have broad-spectrum antimicrobial activities and attract dendritic cells and mast cells. o Examples: Dermicidin produced by sweat glands Defensins and Cathelicidins: produced by neutrophils, macrophages, and epithelia Thrombocidin: produced by platelets Endeavour College of Natural Health endeavour.edu.au 9

Natural Killer Cells o Natural Killer cells: A type of cytotoxic lymphocyte o Present in blood, spleen, lymph nodes and red marrow kill a wide variety of microbes and tumour cells attack any body cells that display abnormal or unusual plasma membrane proteins and cause cytolysis or induce apoptosis kill infected cells and release microbes to be destroyed by phagocytes Endeavour College of Natural Health endeavour.edu.au 10

Phagocytes o Phagocytes: cells that ingest microbes or other particles such as cellular debris o The two major types of phagocytes: Neutrophils Macrophages (developed from monocytes) fixed macrophages stand guard in specific tissues In the skin, liver, lungs, brain, spleen, red marrow and lymph nodes wandering macrophages are in most tissues Endeavour College of Natural Health endeavour.edu.au 11

Phagocytosis o Phagocytosis: the process of ingesting microbes or other particles such as cellular debrisby phagocytes o The five phases of phagocytosis 1. Chemotaxis, 2. Adherence 3. Ingestion 4. Digestion 5. Killing Endeavour College of Natural Health endeavour.edu.au 12

Phagocytosis Endeavour College of Natural Health endeavour.edu.au 13

Phagocytosis 1. Chemotaxis: a chemically stimulated movement of phagocytes to a site of damage chemicals from invading microbes, white blood cells, damaged tissue cells, or activated complement proteins. 2. Adherence: attachment of the phagocyte to the microbe or other foreign material Enhanced by the binding of complement proteins to the invading pathogens 3. Ingestion: a process of engulfing the microbe Caused by pseudopods which in turn merge to form phagosomes. Endeavour College of Natural Health endeavour.edu.au 14

Phagocytosis 4. Digestion: Lysozyme, which breaks down microbial cell walls Other digestive enzymes that degrade carbohydrates, proteins, lipids, and nucleic acids. Lethal Oxidants produced by phagocytes such as superoxide anion (O2 ), Hydrogen peroxide (H2O2) Endeavour College of Natural Health endeavour.edu.au 15

Phagocytosis 5. Killing: The chemical attack of lysozyme, digestive enzymes, and oxidants quickly kills microbes. o A microbe may evade phagocytosis through: capsule formation, toxin production, interference with lysozyme secretion, microbe s ability to counter oxidants produced by the phagocytes. Endeavour College of Natural Health endeavour.edu.au 16

Inflammation o Inflammation: a nonspecific, defensive response of the body to tissue damage o Function: to trap microbes, toxins or foreign material and begin tissue repair o Initiated by damaged cells due to: Pathogens Abrasions Chemical irritations Distortion or disturbances of cell Extreme temperatures Endeavour College of Natural Health endeavour.edu.au 17

Inflammation o Signs of inflammation: Redness Heat Swelling Pain Loss of function depending on the site and extent of the injury. Lawrence, Willoughby, and Gilroy, 2002 2011 Nature Publishing Group, a division of Macmillan Publishers Limited. Endeavour College of Natural Health endeavour.edu.au 18

Stages of Inflammation o Three basic stages of inflammation: 1. Vasodilation and increased permeability of blood vessels, 2. Emigration (movement) of phagocytes from the blood into interstitial fluid, 3. Tissue repair Endeavour College of Natural Health endeavour.edu.au 19

Stages of Inflammation 1. Vasodilation and increased permeability of vessels: o Vasodilation: allows more blood to flow through the damaged area, helps remove microbial toxins and dead cells. o Increased permeability: permit the substances to pass from the blood vessels that normally retained in blood permits defensive proteins such as antibodies and clotting factors to enter the injured area from the blood. Endeavour College of Natural Health endeavour.edu.au 20

Stages of Inflammation 2. Phagocyte emigration within an hour, neutrophils and then monocytes arrive and leave blood stream (emigration) to reach the damaged area. 3. Tissue repair Endeavour College of Natural Health endeavour.edu.au 21

Symptoms of Inflammation: Vasodilation & Capillary Permeability o Vasodilation and increased permeability of vessels: caused by histamine, prostaglandins, leukotrienes from variety of cells Occurs within minutes producing heat, redness and oedema pain can result from injury, pressure from oedema or irritation by toxic chemicals Endeavour College of Natural Health endeavour.edu.au 22

Fever o Fever: an abnormally high body temperature that occurs because the hypothalamic thermostat is reset o Occurs during infection and inflammation o Bacterial toxins trigger release of fever-causing cytokines such as interleukin-1from macrophages o Significance: Intensifies effects of interferons Inhibits bacterial growth Speeds up tissue repair Endeavour College of Natural Health endeavour.edu.au 23

Adaptive (Specific) immunity Endeavour College of Natural Health endeavour.edu.au 24

Adaptive (Specific) immunity o Specific Immunity: The ability of the body to defend itself against specific invading agents such as bacteria, toxins, viruses, and foreign tissues. o Properties: Differs from nonspecific defense mechanisms Specificity: for particular foreign molecules (antigens) and recognize self and non-self Memory: for most previously encountered antigens so that a second encounter produces an even more vigorous response o Immunology: The branch of science that deals with the responses of the body when challenged by antigens Endeavour College of Natural Health endeavour.edu.au 25

Adaptive (Specific) immunity o Adaptive (Specific) Immunity o Antibody Mediated Immunity (AMI) / Humoral Immunity Mediated by B Cells o Cell Mediated Immunity (CMI) Mediated by T Cells Endeavour College of Natural Health endeavour.edu.au 26

Types of adaptive immunity o Cell-mediated immunity (CMI): refers to destruction of antigens by T cells. killer T cells attack antigens helper T cells co-stimulate T and B cells CMI always involves cells attacking cells. Effective against intracellular pathogens, such as fungi, parasites, and viruses; some cancer cells; and foreign tissue transplants. Endeavour College of Natural Health endeavour.edu.au 27

Types of adaptive immunity o Antibody-mediated (humoral) immunity (AMI): refers to destruction of antigens by antibodies. B cells transform into plasma cells, Plasma cells synthesize and secrete specific proteins called antibodies works mainly against antigens dissolved in body fluids (humors) and extracellular pathogens. Effective against bacteria that multiply in body fluids but rarely enter body cells. o Often a pathogen provokes both CMI and AMI immune response Endeavour College of Natural Health endeavour.edu.au 28

Maturation of T Cells and B Cells o B and T Lymphocytes: The cells of specific immunity o Maturation: Derived from: Pluripotent stem cells in red bone marrow B cells: complete their development in red bone marrow. T cells: mature in thymus. o Immunocompetance: Before T cells leave the thymus or B cells leave bone marrow, they acquire several distinctive surface proteins; some function as antigen receptors - molecules capable of recognizing specific antigens. Endeavour College of Natural Health endeavour.edu.au 29

Maturation of T and B Cells Endeavour College of Natural Health endeavour.edu.au 30

Types of adaptive immunity Endeavour College of Natural Health endeavour.edu.au 31

Clonal selection of B and T Cells o Clonal selection: The process by which a lymphocyte proliferates and differentiates in response to a specific antigen o Significance: To form a population of identical cells, called a clones. These recognize the same specific antigen as the original lymphocyte o A lymphocyte that undergoes clonal selection gives rise to two major types of cells in the clone: Effector cells (T and B cells that do) Memory cells (T and B cells that remember) Endeavour College of Natural Health endeavour.edu.au 32

Readings and Resources o Tortora, GJ & Derrickson, B 2014. Principles of Anatomy and Physiology, 14th edn, Wiley. o Harris, P, Nagy, S & Vardaxis, N 2010, Mosby s Dictionary of Medicine, Nursing and Health Professions, 2nd edn, Mosby Elsevier. o Guyton, AC & Hall, JE 2011, Textbook of Medical Physiology, 12th edn, Saunders Elsevier. o Lawrence, T, Willoughby, DA, Gilroy, DW, 2002, Antiinflammatory lipid mediators and insights into the resolution of inflammation Nature Reviews Immunology, vol. 2, pp 787-795 http://www.nature.com/nri/journal/v2/n10/full/nri915.html o Marieb, EN & Hoehn, K 2010, Human Anatomy and Physiology, 8th edn, Benjamin Cummings Pearson. o Moore, KL, Dalley, AF & Agur, AMR 2010, Clinically Orientated Anatomy, 6th edn, Lippincott, Williams & Wilkins. Endeavour College of Natural Health endeavour.edu.au 33

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