defence mechanisms

Question 1

give some examples of non specific defence mechanisms ?

Answer 1

• skin acting as a physical barrier from pathogens
  -mucus in trachea trapping pathogens
  -eyes produce tears , containing enzymes
  -eyelashes + nose hair trapping pathogens before they enter the body
  -trachea has cilia (tiny hairs) -waft pathogens up towards the throat where they are swallowed into stomach and destroyed by HCL
  -PHAGOCYTOSIS

Question 2

what are the two more specific responses ?

Answer 2

humoral responses
cell mediated responses

Question 3

what are humoral responses caused by ?

Answer 3

B-lymphocytes

Question 4

what are cell-mediated responses caused by ?

Answer 4

T-lymphocytes

Question 5

how does your body recognise self cells from non self cells?

Answer 5

molecules on cell surface-especially proteins .
these have a specific 3D tertiary structure that distinguishes one cell from another

Question 6

what is a problem with cell recognition ?

Answer 6

organs/tissue from transplant can be rejected

Question 7

what is colonal selections

Answer 7

when a lymphocyte is complementary to a pathogen and many of them are built up so they can destroy the pathogen

Question 8

how does your body learn to distinguish between self cells and non self cells?

Answer 8

in the featus , lymphocytes are constantly colliding with other cells .
since the featus is protected by the placenta the lymphocytes will almost exclusively collide with self cells
lymphocytes that fit with bodies own cells are suppressed or die :( . the only lymphocytes left are those that might fit non self cells .
lymphocytes produces in bone marrow initially encounter self cells but they any lymphocytes that show a immune response to self cells under go programmed death ( apoptosis )