Immune System
- Created by: Zainaaax
- Created on: 30-08-17 18:49
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- THE IMMUNE SYSTEM
- 1) Primary defence system
- Prevent pathogens from entering the body
- Skin
- HCl in the stomach
- Lysozymes
- Enzymes in tears w/c dissolve bacteria
- Mucus membranes e.g. inside mouth/nose
- Lining of organs inv'd in protection and absorption
- Secrete sticky mucus w/c traps bacteria and lysozyme enzymes
- C/b lined w/ cilia
- Lining of organs inv'd in protection and absorption
- Blood clotting and skin repair
- Body prevents excess blood loss, clot = temp' seal
- Prevents infection bc pathogen can't enter
- Scab forms-> epidermis (outer layer of skin) heals
- Body prevents excess blood loss, clot = temp' seal
- Inflammation
- Caused by damaged cells
- Releases histamines
- Cause capillaries to dilate
- Incr'd tissue fluid
- Incr'd phagocyte supply
- Releases histamines
- Caused by damaged cells
- Expulsive reflexes e.g. coughing/ sneezing
- Expel path's trapped in mucus
- Remove from airway tract
- Goblet cells in trachea secrete gel- like mucus
- Traps path's and irritants w/c are inhaled
- Cilia cells lining resp' tract waft mucus towards back of throat
- Cough reflexes expel mucus and clear airway
- 2) Phagocytosis
- Non- specific response
- Phagocytes = WBC, engulfs path's
- Found in blood/tissues
- Phagocytes = WBC, engulfs path's
- 1) Phag' recognises antigens on path'
- 2) Cytoplasm of phag' moves round path' -> engulfs
- Made easier by presence of opsonins- mols in blood that attach to foreign antigens
- 3) Path' is now contained in a phagosome (type of vesicle) in cytop' of phag'
- 4) Lysosome (organelle w/c cont's digestive enzymes) fuses w/ phagosome
- Enzymes break down path'
- 5) Phag' presents path's antigens on surface.
- Sticks antigens on surface to activate other IS cells.
- When phag' does this = antigen-presenting cell
- 4) Lysosome (organelle w/c cont's digestive enzymes) fuses w/ phagosome
- 2) Cytoplasm of phag' moves round path' -> engulfs
- Neutrophils = type of phag'
- The first WBC to respond to path' inside body
- Move towards wound in response to signals from cytokines (proteins w/c act as messenger mols)
- Non- specific response
- 3) T-Lymphocyte activation
- Type of WBC. Surface covered w/ receptors
- C/o diff' functions
- T helper cells - release subs to activate B lymphs
- T killer cells - attach to antigens on path' and kill cell
- T regulatory cells - suppress immune response from other WBC
- Helps to stop IS cells from mistakenly attacking own body cells
- Some become memory cells
- C/o diff' functions
- When receptor on surface meets complem'ry antigen -> binds
- Activates T-lymph = clonal selection
- Activated t-lymph undergoes clonal expansion
- Divides to prod' clones w/c differentiate into diff' types
- Type of WBC. Surface covered w/ receptors
- 4) B-Lymphocyte acitvation
- Type of WBC, covered w/ antibodies- proteins that bind antigens
- Form antigen-antibody complex
- Antibodies are diff' shapes, bind to diff' antigens
- Form antigen-antibody complex
- 1) Antibody on surface of B lymph' meets complem'ry antigen -> binds
- 2) This + subs released from T helper cells activates B lymph
- Clonal selection
- 3) Activated B lymph divides by mitosis -> plasma cells and memory cells
- Clonal expansion
- Plasma cells = clones of B-lymphs
- Secrete loads of antibody specific to antigen into blood
- AB bind to specific AG -> complexes
- Signal for IS to attack and destroy path'
- AB bind to specific AG -> complexes
- Secrete loads of antibody specific to antigen into blood
- 2) This + subs released from T helper cells activates B lymph
- Type of WBC, covered w/ antibodies- proteins that bind antigens
- 1) Primary defence system
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