6.3 Response to infection
- Created by: phoebeschofield02
- Created on: 02-01-19 17:42
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Non-specific responses to infection
-Inflammation -->
- occurs when an infection is localised
- when tissue is damaged, mast cells and basophils release histamines
- histamines cause arterioles to dilate, causing heat and tenderness
- histamiens also make capillary walls leaky
- meaning plasma containing leucocytes and antibodies is forced out of the capillaries, causing swelling and pain
- the antibodies disable the pathogens
-Fever -->
- when a pathogen infects the body, the hypothalamus makes the body temp higher
- most pathogens reproduce @ lower than 37 degrees C, so a higher temp means less pathogen reproduction
- the immune system works better at higher temps so will be better at combating the pathogen @ a higher temp
- if fevers get too high, they may denature some enzymes and this can lead to tissue damage and even death
-Phagocytosis
- a non-specific response involving leucocytes
- 2 main types of leucocytes are granulocytes and agranulocytes
- neutrophils are granulocytes and can ingest only a few pathogens at a time and cannot renew their lysosomes
- macrophages are agranulocytes that can renew their lysosomes and accumulate at the site of infection to attck invading pathogens
- phagocytes engulf the pthogen and enclose it in a vesicle
- the vesicle (phagosome) joins w/ the lysosomes and the enzymes in the lysosomes breaks down the pathogen]the phagocytes then produce cytokines that stimulate other phagocytes to move to the site of infection
Different kinds of lymphocytes
-B cells -->
- are produced in the bone marrow
- once mature, they are found in the lymph glands and free around the body
- B cells have receptor proteins on their surface that are identical to the antibodies they will produce
- when a B cell binds to an antigen it produces:
- B effector cells= they divide to form the plasma cell clones
- Plasma cells= they produce antibodies to particular antigens
- B memory cells= they provide immunological memory to a specific antigen
-T cells -->
- are produced in the bone marrow but mature and become active in the thymus gland
- the surface of every t cell displays htousands of identical t-cell receptors
- t cell receptors bind to antigens on the infected body cells and produce different types of t cells:
- T killer cells= produce chemicals to destroy the infected body cells
- T helepr cells= activate the plasma cells to produce antibodies agaisnt the antigens on a particular pathogen and secrete opsonins which label the pathogen for phagocytosis
- T memory cells= are long lived cells that make up part of the immunological memory. When they meet a pathogen for a second time, they divide rapidly to produce large amounts of T killer cells
The humoral response
-reacts to antigens found outside of the body
-results in the production of antibodies
-T helper activation -->
- duirng phagocytosis…
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