Phagocytosis

Question 1

What do phagocytes do

Answer 1

ingest and destroy pathogen by phagocytosis before it can cause harm

Question 2

What does phagocytosis do

Answer 2

-engulf large particles eg bacteria by cells in vesicles formed from cell-surface membrane

Question 3

How can phagocytes provide an important defence against pathogens

Answer 3

-travel in the blood but can move out of the blood vessels into other tissues

Question 4

Describe first line of defence against disease

Answer 4

physical and chemical barriers e.g. HCl in stomach, skin, cilia and mucus in respiratory system

Question 5

Process of phagocytosis

Answer 5

-phagocyte attracted to chemicals secreted by pathogen/damaged body cells
-receptors on phagocytes cell surface membrane recognise and attaches to chemicals on the surface of pathogen
-phagocyte engulfs pathogen to form vesicle (phagosome)
-lysosome move towards phagosome and fuse with it (phagolysosome)
-lysozymes (enzymes) in lysosome hydrolyse pathogen (hydrolysis of their cell wall)
-soluble products from break-down of pathogen absorbed into cytoplasm of phagocyte

Question 6

Describe role of lysosomes in phagocytosis

Answer 6

-migrate towards phagosome formed by engulfing bacterium
-lysosomes release their lysozymes into phagosome where they hydrolyse the bacterium

Question 7

Why is phagocytosis a non-specific defence mechanism

Answer 7

as the phagocyte has multiple different receptors that can detect different pathogens. It does NOT have a single receptor that is only complementary to one pathogen.