DEFENCE AGAINST INFECTIOUS DISEASE AHL Topic 11.1 IB Biology Miss Werba

AHL TOPIC 11 – FURTHER PHYSIOLOGY 11.1 DEFENCE AGAINST INFECTIOUS DISEASE 11.2 MUSCLES & MOVEMENT 11.3 THE KIDNEY 11.4 REPRODUCTION J WERBA – IB BIOLOGY 2

THINGS TO COVER Blood clotting & thrombin Challenge & response principle Clonal selection for immunity Memory cells for immunity Passive & active immunity Antibody production Monoclonal antibodies for diagnosis & treatment Vaccinations J WERBA – IB BIOLOGY 3

BLOOD CLOTTING Command term = DESCRIBE 11.1.1 BLOOD CLOTTING Command term = DESCRIBE Blood clotting is involves a chain of biochemical reactions. It forms part of the body’s first line of defence against disease. Allows us to seal wounds and prevent excess blood loss. J WERBA – IB BIOLOGY 4

BLOOD CLOTTING Command term = DESCRIBE 11.1.1 BLOOD CLOTTING Command term = DESCRIBE Blood clotting involves platelets. Platelets are fragments of much larger cells. They contain granules filled with chemicals that act in the clotting process, including: Serotonin Ca2+ ions Enzymes ADP J WERBA – IB BIOLOGY 5

BLOOD CLOTTING Command term = DESCRIBE 11.1.1 BLOOD CLOTTING Command term = DESCRIBE A blood clot consists of: a plug of platelets within a network of insoluble fibrin fibres Aggregation of platelets and fibrin formation both require the proteolytic enzyme thrombin. Clotting also requires: calcium ions a dozen or so protein clotting factors. J WERBA – IB BIOLOGY 6

BLOOD CLOTTING Command term = DESCRIBE 11.1.1 BLOOD CLOTTING Command term = DESCRIBE Wound exposes collagen layer in extracellular matrix. Platelets adhere to exposed collagen and degranulate, releasing contents of their granules. This promotes further platelet adhesion and formation of a platelet plug. The damaged tissue initiates coagulation by releasing clotting factors and triggering a cascade of reactions that activate Factor X. J WERBA – IB BIOLOGY 7

BLOOD CLOTTING Command term = DESCRIBE 11.1.1 BLOOD CLOTTING Command term = DESCRIBE Activated Factor X binds and activates Factor V, forming prothombinase. Prothombinase coverts prothrombin (Factor II) to thrombin. Thrombin converts fibrinogen (Factor I) to fibrin. Fibrin is a fibrous protein and forms an insoluble mesh. Red blood cells (RBCs) and platelets get trapped in the mesh – the clot. J WERBA – IB BIOLOGY 8

BLOOD CLOTTING Command term = DESCRIBE 11.1.1 BLOOD CLOTTING Command term = DESCRIBE Platelets Damaged blood vessels. Exposure to air. Prothrombin in plasma Clotting factors Thrombin Fibrinogen (soluble) Fibrin fibres (insoluble) RBCs CLOT J WERBA – IB BIOLOGY 9

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE J WERBA – IB BIOLOGY 10

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE 1st line of defence: unbroken skin, mucous secretions, body secretions, gut 2nd line of defence: Inflammation  increases blood flow Non-specific cellular response  platelets, leucocytes Fever  kills pathogens; increases activity of IS Protein responses  complement, interferon J WERBA – IB BIOLOGY 11

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE 3rd line of defence: Involves the immune response Antigen presentation Activation of Helper T cells Activation of B cells Production of plasma cells Production of memory cells J WERBA – IB BIOLOGY 12

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE ANTIGEN PRESENTATION: Pathogen invades the body. The pathogen’s antigen is detected as “non-self” by macrophages. Macrophage try to ingest the pathogen (phagocytosis) but the ingestion isn’t complete. Macrophage displays the bacterial antigen on its own cell membrane. Macrophage has become an antigen presenting cell (APC). Pathogen invades Phagocytosis Antigen presenting cell (APC) formation J WERBA – IB BIOLOGY 13

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE ANTIGEN PRESENTATION: Antigen is absorbed and then displayed by the macrophage Antigen presentation by macrophage MHC protein J WERBA – IB BIOLOGY 14

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE APC presents antigen to lymphocytes Activates complementary Helper T cell Helper T cell divides HELPER T CELL ACTIVATION: The APC comes into contact with lymphocytes. A Helper T (TH) cell complementary to the antigen on the APC will be identified. Selected TH cell divides by mitosis forming a clone. These processes are known as clonal selection & clonal expansion. Memory T cells are also formed. J WERBA – IB BIOLOGY 15

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE HELPER T CELL ACTIVATION: Inactive Helper T-cell Macrophage sends a signal to activate the helper T-cell Active Helper T-cell J WERBA – IB BIOLOGY 16

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE B CELL ACTIVATION: The TH cells activate complementary B cells The B cells also divide to form a clone. Helper T cell presents antigen to B cells Activates complementary B cell B cell divides J WERBA – IB BIOLOGY 17

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE B CELL ACTIVATION: Active Helper T-cell Antibody Activated Helper T-cell sends a signal to activate the B-cell Activated Helper T-cell binds to B-cell Inactive B-cell Active B-cell J WERBA – IB BIOLOGY 18

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE PLASMA CELL FORMATION: Activated B cells differentiate into plasma cells. Plasma cells make large amounts of antibody proteins. The antibodies are secreted by exocytosis. Differentiation of B cell Plasma cell formation Antibody production J WERBA – IB BIOLOGY 19

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE MEMORY CELL FORMATION: Activated B cells also differentiate into memory B cells. Memory cells remain after immune response. Allow a rapid response if the disease is encountered again (= LONG TERM IMMUNITY) Differentiation of B cell Plasma cell formation Antibody production Memory B cell formation Long term immunity J WERBA – IB BIOLOGY 20

11.1.2 J WERBA – IB BIOLOGY 21

THE IMMUNE RESPONSE Command term = OUTLINE 11.1.2 THE IMMUNE RESPONSE Command term = OUTLINE J WERBA – IB BIOLOGY 22

ANTIBODY PRODUCTION Command term = EXPLAIN 11.1.4 ANTIBODY PRODUCTION Command term = EXPLAIN Antibodies (immunoglobulins): proteins produced as a response to the presence of an antigen. General structure of an antibody: 2 antigen-binding sites MHC proteins (major histocompatibility complex) T cell receptors do not respond to antigens unless the antigens are associated with MHC proteins J WERBA – IB BIOLOGY 23

ANTIBODY PRODUCTION Command term = EXPLAIN 11.1.4 ANTIBODY PRODUCTION Command term = EXPLAIN The antibodies produced by a plasma cell are complementary to the original antigen presented on the pathogen. J WERBA – IB BIOLOGY 24

ANTIBODY PRODUCTION Command term = EXPLAIN 11.1.4 ANTIBODY PRODUCTION Command term = EXPLAIN What happens after the antibody has bound to the antigen? Enhances phagocytosis Leads to cell lysis http://kvhs.nbed.nb.ca/gallant/biology/antibody.jpg J WERBA – IB BIOLOGY 25

IMMUNITY Command term = DEFINE 11.1.3 IMMUNITY Command term = DEFINE Immunity: having sufficient biological defences against infection Active immunity: immunity due to the production of antibodies by the organism itself after the immune response has been stimulated by a pathogen Passive immunity: immunity due to acquisition of antibodies from another organism in which active immunity has been stimulated J WERBA – IB BIOLOGY 26

IMMUNITY Command term = DEFINE 11.1.3 IMMUNITY Command term = DEFINE Acquired immunity Naturally acquired Active Infection; contact with pathogen eg. chicken pox immunity Passive Antibodies pass from mother to baby eg. via placenta & colostrum Artificially acquired Vaccine; dead or attenuated pathogens eg. MMR vaccine Injection of antiserum eg. rabies treatment J WERBA – IB BIOLOGY 27

VACCINATIONS Command term = EXPLAIN 11.1.6 VACCINATIONS Command term = EXPLAIN The secondary response to an antigen is much faster and stronger than the first response. Vaccinations deliberately expose someone to a disease so that they develop immunity – without them having to contract the illness itself. Vaccines contain a form of the pathogen or toxin that has been modified (attenuated) so that it is unable to harm the body Exposure to an attenuated pathogen still allows the production of memory cells against the antigen J WERBA – IB BIOLOGY 28

VACCINATIONS Command term = EXPLAIN 11.1.6 VACCINATIONS Command term = EXPLAIN J WERBA – IB BIOLOGY 29

VACCINATIONS Command term = DISCUSS 11.1.7 VACCINATIONS Command term = DISCUSS BENEFITS: Protects the individual Eradication of some diseases – eg. smallpox Fewer people get certain diseases – eg. measles Prevents disability – eg. paralysis from polio Herd immunity – reduces spread, even to people not vaccinated, because they will probably not come into contact with the disease as frequently Reduced economic burden on healthcare system Prevention of pandemics and epidemics J WERBA – IB BIOLOGY 30

VACCINATIONS Command term = DISCUSS 11.1.7 VACCINATIONS Command term = DISCUSS DANGERS: Overloading the immune system - will reduce the ability to handle other infections Could contain other harmful substances – eg. mercury now not used in vaccines Allergies and side effects Mixing vaccines - haven’t really studied what happens when a mixture of antigens are presented together (eg. MMR vaccination) Artificial immunity is less effective J WERBA – IB BIOLOGY 31

MONOCLONAL ANTIBODIES Command term = DESCRIBE 11.1.5 MONOCLONAL ANTIBODIES Command term = DESCRIBE Antibodies can be produced in a lab for therapeutic or diagnostic use. Monoclonal antibodies are derived from a single cell. They are pure antibody preparations that are specific for a single antigen. The current technology for making monoclonal antibodies involves fusion of tumour cells and B cells. J WERBA – IB BIOLOGY 32

MONOCLONAL ANTIBODIES Command term = DESCRIBE 11.1.5 MONOCLONAL ANTIBODIES Command term = DESCRIBE PRODUCTION: A mammal (eg. mouse) is injected with the antigen. The mouse plasma cells will produce antibodies against the antigen. The mouse plasma cells complementary to the antigen are extracted and fused with tumour cells  form a hybridoma cell The hybridoma cell divides and produces identical antibodies to the original plasma cells The antibody can then be harvested. J WERBA – IB BIOLOGY 33

MONOCLONAL ANTIBODIES Command term = DESCRIBE 11.1.5 MONOCLONAL ANTIBODIES Command term = DESCRIBE J WERBA – IB BIOLOGY 34

MONOCLONAL ANTIBODIES Command term = DESCRIBE 11.1.5 MONOCLONAL ANTIBODIES Command term = DESCRIBE USES: Pregnancy testing detects the presence of the HCG hormone in the urine HCG is only released during pregnancy Testing for a suspected heart attack Damaged heart muscle cells release a specific cardiac enzyme into the blood ELISA test for HIV Colour change in dimple tray when antibodies are detected Treatment for rabies Diagnosis of malaria J WERBA – IB BIOLOGY 35

Sample questions Q1. What are fused in the production of monoclonal antibodies? A. Tumour cells and T cells B. Tumour cells and B cells C. B cells and T cells D. Antibodies and antigens J WERBA – IB BIOLOGY 36

Sample questions Q2. State one use of monoclonal antibodies in diagnosis and one use in treatment. [2] Q3. Outline the principle of immunity. [6] J WERBA – IB BIOLOGY 37

Sample questions A1. B A2. Diagnosis: Treatment: detection of (antibodies to) HIV; detection of HCG / pregnancy test kits; detection of cardiac enzyme in suspected heart attacks; detection of tissue / blood type; testing for (different strains of) malaria; ELISA test; Treatment: targeting cancer cells with attached drugs; treatment of rabies / Ebola / lymphoma destroying T-cells to reduce rejection of transplants; 2 max J WERBA – IB BIOLOGY 38

Sample questions A3. immunity is the ability of an organism to resist infection; due to presence of (specific) antibodies; immunity can be active or passive; passive due to receiving antibodies from external sources/ across placenta/from breast milk/injection; active results from facing an infection directly/through vaccination; pathogen/foreign cell invades body; leads to clonal selection / formation of B memory cells; B-cells produce specific antibodies; if same pathogen enters body again memory cells activated / stimulated to divide; antibodies produced faster and in greater amounts; J WERBA – IB BIOLOGY 39