phagocytosis Flashcards
6
Phagocytosis
the eating or engulfment of bacteria or cellular debris by a body cell
Phagocytes
- are WBCs of the INNATE immune response that recognize the material as foreign and engulf it (digest it) to render it harmless
- there are two types, free and fixed
what are the 2 types of phagocytes
free phagocytes
fixed phagocytes
describe free phagocytes
- phagocytes that circulate in the blood and are free to migrate anywhere in the body as required
- neutrophils are the best examples
describe fixed phagocytes
- cells of the reticuloendothelial system (RES)
- monitor the blood circulating through the RES
- phagocytize foreign material and worn-out cells
describe the RES
reticuloendothelial system
- large system of cells located in the spleen, liver, bone marrow, and connective tissue
what do RE cells (part of the RES) in the liver do?
- line the sinusoids (contains venous blood from portal vein)
- the reticuloendothelial cells remove undesirable material from the blood as blood flows in the sinusoids from the total vein
Phagosome
the membrane that initially surrounds a foreign particle
what are the steps of phagocytosis
- Formation of a phagosome around a foreign particle
- Lysosomes move towards the phagosome, merge with it, and transfer their digestive enzymes into the phagosome. The structure is now called the digestive vacuole.
Lysosomes
small sacs of digestive enzymes within the cytoplasm of the phagocyte
digestive vacuole
phagosome (bacteria + surrounding membrane)
+
the digestive enzymes that the lysosomes transferred into it after merging with it
- this is where particles are blocked down which forms residual bodies
- the residual bodies are eliminated from the cell
in what stage of phagocytosis do particles begin to be broken down
when it is a digestive vacuole
residual bodies
the broken-down particles of the phagocytized foreign material
