Topic 6.3 Immune response Flashcards
Mrs Richardson (25 cards)
Inflammation
- White blood cells are drawn to the infected area
- They fight and eliminate the pathogen
- Innate tissue repair
Symptoms of Inflammation
fever, heat and swelling
Fever
- When infected by a pathogen, the hypothalamus raises your body temperature.
- inhibits bacteria growth.
How inflammation works?
- Mast cells and basophils release chemicals called histamines.
- The histamines cause blood vessels to dilate causing local heat and redness.
- This makes it harder for the pathogen to reproduce.
- The dilated blood vessels also cause plasma, containing leukocytes and antibodies, to be forced out of the capillaries.
- The antibodies disable the pathogens, therefore allowing phagocytes to destroy them.
Mast cells
- Mast cells do not circulate in the bloodstream, they live in skin and mucosal tissues
- When activated they release histamines
Phagocytes
- They detect foreign antigens
- The phagocyte engulfs the pathogen to form a phagosome
Basophils
- They produce and release histamines
- they circulate in the bloodstream and they are not phagocytic
Eosinophils
- Particular type of phagocyte
- They have the characteristic ‘lobed nucleus’ allowing it to morph shape in order to engulf pathogens
- They also produce chemicals which are able to counteract the inflammatory histamines
Natural killer cell
- Type of leukocyte that can recognise cells that are infected with as virus and cancer cells
- They release proteins that induce programmed cells death by perforating the membrane of the damaged cell
- This kills the infected/cancerous cells
Primary response vs Secondary response
- Primary is slower as you do not have the memory cells
- Secondary has a rapid response of antibodies as you have memory cells
Artificial passive immunity
Gaining antibodies from an outside source
- Positives: immediate don’t need to wait for antibodies to be made
- Negative: Short term the person will not have long lasting protection
Passive immunity
- When antibodies are introduced from an outside source
Natural passive immunity
- When an infant receives a mothers antibodies through the placenta or breast milk
Active immunity
- Involves exposure to a pathogen/antigen
Natural active immunity
Through natural exposure eg. having a cold
Artificial active immunity
Through vaccination
Vaccination
- Vaccination aims to stimulate a primary immune response without actually causing the disease like a normal infection would
- This allows people to safely develop memory cells against a pathogen
Summary of Active immunity
- Requires exposure to antigen (Through vaccine or infection)
- Body makes own antibodies
- Develops slowly
- Long term because memory cells enable faster antibody production on re-infection
Summary of passive immunity
- Does Not require exposure to the antigen
- The body is given antibodies made by someone else (eg. injection, across the placenta or in breast milk
Immediate - Short term as antibodies are broken down and no memory cells are made
Steps of phagocytosis
- Pathogen comes along and phagocyte engulfs the pathogen
That forms a phagosome - Binds with a lysosome containing digestive enzymes forming a Phagolysosome
- That presents to antigen on the MHC
- Cytokines are released
- A T helper cell comes along and activates the B cells which divide and form plasma cells
- The plasma cells release the antibodies and you will end up with memory B cells
T killer cells (Cytotoxic/CD8+)
- An antigen presenting cell eg. macrophage digests and engulfs the pathogen and presents it on its surface via MHC
- Killer T cell with a complimentary T cell receptor binds to the MHC/antigen presenting cells
- With the assistance of cytokines from an activated helper T cell the killer T cell becomes activated
- Activated T killer cells and T killer memory cells are formed
- Active T killer cells release perforin chemicals
- These punch holes in the membranes of infected cells and cause them to burst (Cell lysis)
Opsonins
Antibodies that bind with antigens to act as markers so that phagocytes can recognise foreign cells and destroy them
Agglutinins
Antibodies that bind to antigens , causing foreign substances to clump together, which prevents them from entering cells and reproducing
Lysins
Antibodies that bind to antigens and cause a foreign cell to rupture or disintegrate
