non specific animal defences against pathogens (chapter12) Flashcards
1
Q
non specific defences - keeping pathogens out
A
- the skin, mucous membranes that secrete mucus to trap microorganism, lysozymes in tears and urine, acid in the stomach.
2
Q
blood clotting and wound repair
A
thromboplastin : an enzyme that triggers blood clotting.
serotonin : makes smooth muscles in the blood vessel contract to reduce blood supply to the area.
- the clot dries out, forming a hard tough scab to keep pathogens out.
- epidermal cells below the scab grow, sealing the wound.
- collagen fibers are de[posited to give new tissue strength.
3
Q
inflammatory response
A
- histamine and cytokines are released by the damaged tissue.
-histamines make the blood vessels dilate , causing heat and redness, preventing pathogens reproducing. - cytokines attract white blood cells causing phagocytosis.
4
Q
non specific defences - getting rid of pathogens
A
- fevers : cytokines stimulate the hypothalamus to increase body temperature, this inhibits pathogen reproduction.
- phagocytosis : engulf and destroy pathogens, 2 types of pathogens are neutrophils and macrophages.
5
Q
stages of phagocytosis
A
- pathogens produce chemicals that attract phagocytes
- phagocytes recognized non-human proteins on the pathogen.
- the phagocyte engulfs the pathogen and encloses it in a vacuole called the phagosome.
- The phagosome combines with a lysosome to form a phagolysosome
- enzymes from the lysosome digest and destroy the pathogen.
6
Q
opsonins
A
Chemicals that bind to pathogens and tag them so they can be more easily recognized by phagocytes. Phagocytes have receptors on their cell membranes that bind to the opsonins and then engulf the pathogens.
7
Q
cytokines
A
- act as cell signalling molecules, informing other phagocytes that the body is under attack and stimulating them to move to the site of infection
- can also stimulate the specific immune system and increase body temp.
