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
Monoclonal antibodies
Vaccine/vaccinations
- A preparation of containing antigens to stimulate active immunity against 1 or several diseases.
- Vaccination is giving a vaccine containing antigens by injection or by mouth. It gives the artificial active immunity without the development of the symptoms of disease.
Cytokines
Any signaling molecule released by cells to influence growth and/or differentiation of the same or another cell
