Immunity Flashcards
External defence system
-Physical ,chemical ,cellular
Examples:
Epithelia in airways
hydrochloric acid
blood clotting
Internal defence system
-WBC
- any molecule which body recognizes as foreign is an ANTIGEN
-Immune system has ability to distinguish between SELF & NON-SELF
-production of ANTIBODIES is an IMMUNE RESPONSE of Lymphocytes , at other times they kill infected cells
Antigen
A substance which is foreign to the body and stimulates an immune response
Self & Non-self
- Refers to substances produced by the body that the immune system does not recognize and so don’t stimulate an immune response.
- Refers to any substance or cell that is recognized by the immune system as being foreign and will stimulate an immune response
Antibodies
- A Glycoprotein (immunoglobulin)
made by specialized lymphocytes in response to the presence of a specific antigen
-Each type of antibody molecule has a shape that is complementary to its specific antigen.
Immune response
-The complex series of responses of the body to entry of foreign antigen
-it involves the activity of of lymphocytes and phagocytes.
Phagocytes
-Produced throughout life in bone marrow
-60% of WBC are neutrophils
-neutrophils accumulate at site of infection and die after ingesting pathogen
-Monocyte in blood (to travel) turns to Macrophage in organs
- Macrophages are long living cells that cut up pathogen to display antigens which is recognized by lymphocytes
Phagocytosis
- Cells being attacked release chemicals eg. Histamine
- which attract neutrophils (CHEMOTAXIS)
- neutrophil attaches to pathogen covered in antibodies*
- Cell surface membrane of neutrophil engulfs pathogen (endocytosis)trapping it in a phagocytic vacuole (phagosome)
- Lysosome fuses with the vacuole and enzymes break down the pathogen
Lymphocytes
- Produced before birth in bone marrow, only mature L can carry out immune response
- Each type of B/T Lymphocyte are specialized to respond to one antigen
- Circulate between blood and lymph to come in contact with pathogens
- B Lymphocytes mature in bone marrow, T in thymus
B - Lymphocytes production
- Immature B cells divide by mitosis
- each B cell matures
- small group of identical cells called a CLONE
-production of receptors and placement in cell surface membrane
- Clonal selection , where a B cell is selected to go through clonal expansion
-Clonal expansion, some B cells become plasma cells which produce large quantities of antibodies quickly and some become memory cells which, during 2nd immune response if pathogen is reintroduced, they recognize antigen , divide rapidly
-
T-Lymphocytes production
-Collect in gland called thymus where they mature
- have specific Cell surface receptors called T-cell receptors similar to antibodies and specific to antigen
-ANTIGEN PRESENTATION allows T-cells to detect pathogens
-3 types: Killer, Helper and Memory
-when T cells are activated they release CYTOKINES which stimulate B cell division
- Immature T-cells divide by mitosis
-production and placement of receptors in cell surface membrane
-Maturation in thymus forms 4 different clones
T-Helper:
-divide by mitosis
-secrete cytokines which activate B cells to produce memory cells and plasma cells/ T- Helper memory cells
T-Killer:
-killers punch small holes in the cell surface membrane of infected cell and then vacuoles full of toxins are released which kill cell/ T-Killer memory cells
Antibodies
-Globular glycoproteins
-form group of plasma proteins called
immunoglobulins
-chains are held together by disulfide bonding
- Sequences of amino acids in variable regions make specific 3D shapes which bind to 1 antigen
- Hinge region gives flexibility in binding antibody to antigen
- Has 2 light and 2 heavy polypeptide chains
- has 2 chains of sugar molecules
Different ways antibodies work
- Combine with viruses
2.Attach to flagella making bacteria less active
- Multiple antigen binding sites can clump bacteria together
- Punch holes in cell wall of bacteria causing them to burst
- coat bacteria
- ANTITOXINS, antibodies combined with toxins which neutralize them making them harmless
Active (artificial + natural)
- Active immunity is immunity gained when an antigen enters the body and immune response occurs and antibodies are produced by plasma cells
- Artificial active immunity is immunity gained by putting antigens into the body by injection or by mouth eg. Vaccinations
- Natural active immunity is immunity gained by being infected by pathogen
Passive (artificial+natural)
-Passive immunity is immunity gained without there being an immune response
-Artificial passive immunity is immunity is gained by injecting antibodies
-Natural passive immunity is immunity gained by a fetus when maternal antibodies cross the placenta or immunity gained by an infant
