5.2 Phagocytosis Flashcards
What are the two types of white blood cell?
Phagocytes and lymphocytes
What is the role of phagocytes?
They ingest and destroy the pathogen by phagocytosis before it can cause harm
What is the second line of defence?
Phagocytosis
What happens in phagocytosis?
Large particles, such as bacteria, can be engulfed by cells in the vesicles formed from the cell surface membrane
Which white blood cells carry out phagocytosis?
Phagocytes
Where do phagocytes move?
Some travel in the blood but can move out of blood vessels into other tissues
(Phagocytosis) why do phagocytes move towards a pathogen?
Chemical products of pathogens or dead, damaged and abnormal cells act as attractants so phagocytes move towards the pathogen
(Phagocytosis) how do phagocytes recognise pathogens?
They have several receptors on their cell-surface membrane that recognise, and attach to, chemicals on the surface of the pathogen
(Phagocytosis) what happens when phagocytes engulf the pathogen?
They form a vesicle (phagosome)
(Phagocytosis) what happens to the phagosome?
Lysosomes move towards the vesicle and fuse with it
(Phagocytosis) what happens when lysosomes fuse with the phagosome?
Lysozymes in the lysosomes destroy ingested bacteria by hydrolysis of their cell walls (same process as the digestion of the food in the intestines) they release their lysozymes into the phagosome
(Phagocytosis) what happens to the soluble products of the breakdown of the pathogen?
They are absorbed into the cytoplasm of the phagocyte
Why are lysozymes found in tears?
The protective covering of the eye and the eye are possible entry points for pathogens therefore the eyes are vulnerable to infection. Protective layer of the eye is thin to allow light through . Lysozymes will break down the cell walls of any bacterial pathogens and destroy them before they can cause harm
