Animal defences against Pathogens (Non-specific)
- Created by: ebcrankomills
- Created on: 27-05-19 10:41
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- Animal defences against pathogens (non-specific)
- Blood clotting and wound repair
- Platelets come into contact with skin or collagen, they adhere and begin to secrete different substances.
- Thrombo-plastin is secreted, it is an enzyme which triggers reactions resulting in the formation of a blood clot
- Serotonin is secreted, this narrows the blood vessels in that area, reducing the flood of blood to the wound. This is done by contracting the smooth muscle in the vessel walls
- Inflammatory response
- Inflammation is characterised by pain, heat, redness and swelling of tissue
- In damaged tissue most cells are activated to release cytokines and histamines
- Cytokines attract phagocytes to the site they then dispose of pathogens via phagocytosis
- Phagocytosis
- When a macrophage has digested a pathogen it combines antigens from pathogen surface with special glycoproteins called MHC
- MHC= major histo-compatibility complex
- MHC moves the pathogens antigens to the macrophages own surface membrane it becomes and APC
- APC = Antigen Presenting cells
- The stages of pahgocytosis
- 1) Pathogens produced chemicals to attract phagocytes
- 2) Recognise non-human proteins of pathogen.
- 3) Phagocytes engulf pathogens and enclose in a phagosome (type of vacuole)
- 4) Phagosome combines with lysosome to form a phagolysosome
- 5) Enzymes from lysosome digest and destroy pathogen
- Phagocytosis
- Histamines
- Dilate blood vessels causing localised redness and heat, a high temp prevents pathogens reproducing
- Blood vessel walls become more 'leaky,' blood plasma is forced out making tissue fluid. Tissue fluid causes swelling and pain
- Fevers
- Normal body temperature is around 37 degrees
- high temperatures can inhibit pathogen reproduction
- Specific immune system works better at higher temps
- Cytokines stimulate the hypothalamus to reset bodily temperature
- Phagocytosis
- When a macrophage has digested a pathogen it combines antigens from pathogen surface with special glycoproteins called MHC
- MHC= major histo-compatibility complex
- MHC moves the pathogens antigens to the macrophages own surface membrane it becomes and APC
- APC = Antigen Presenting cells
- The stages of pahgocytosis
- 1) Pathogens produced chemicals to attract phagocytes
- 2) Recognise non-human proteins of pathogen.
- 3) Phagocytes engulf pathogens and enclose in a phagosome (type of vacuole)
- 4) Phagosome combines with lysosome to form a phagolysosome
- 5) Enzymes from lysosome digest and destroy pathogen
- Counting blood cells
- Often stained to allow you to see the nuclei of lymphocytes
- Helpful chemicals
- Phagocytes produce cytokines after they have engulfed a pathogen.
- Cytokines are cell signalling molecules and can also increase bodily temperature.
- Opsonins bind to pathogens and 'tag,' them this allows them to be more easily recognised.
- Phagocytes have receptors that bind to common opsonins, the phagocytes then engulfs the pathogen
- Blood clotting and wound repair
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