important processes (MEMORISE )

Question 1

phagocytosis

Answer 1

1) phagocyte is attracted by chemicals produced by the pathogen 2) phagocyte recognises pathogen as non-self and binds to it 3) phagocyte engulfs the pathogen to form phagosome - lysosome moves towards phagosome and combines with it forming a phagolysosome 4) In phagolysosome, enzymes break down the pathogen 5) Digested pathogen absorbed by phagocyte - antigens combine with MHC in the cytoplasm 6) MHC is displayed on phagocyte membrane, making an antigen presenting cell (APC)

Question 2

antibodies

Answer 2

Y shaped glycoproteins

Question 3

saprotroph

Answer 3

obtain nutrition from dead organic matter

Question 4

what happens in the response to cell-mediated immunity

Answer 4

1) APC presents the antigen on the surface of the cell 2) T helper cells have receptors which complement the antigen 3) when the t helper cell binds to the antigen, the t helper cell becomes activated (clonal selection) 4) They produce interleukins 5) this stimulates more T cells that are specific to the antigen to divide and form clones (clonal expansion) 6) the clones then do one of four things: - produce interleukins to stimulate phagocytosis -produce interleukins to stimulate B cells to divide - differentiate into T killer cells - differentiate into T memory cells

Question 5

how does the body respond to humoral immunity?

Answer 5

1) B lymphocytes covered in antibodies bind to specific antigens (clonal selection) OR B lymphocytes engulfs the pathogen and present the antigen on the surface 2) With the help from the T helper cell interleukins, the B cells are activated and divide by clonal expansion 3) the clones develop into either plasma cells producing antibodies or into memory cells

Question 6

the process of blood clotting

Answer 6

When you cut yourself: -Platelets come in contact with collagen in the skin -Platelets stick to each other -Secrete several substance Thromboplastin – enzyme that leads to the formation of a blood clot Serotonin – causes smooth muscle in walls to contract (narrowing reduces blood supply to area -Clot dries out, forming a hard, tough scab -Epidermal cells below start to grow, sealing wound permanently -Damages blood vessels regrow -Collagen fibres deposited to give new tissue strength