The phagocytosis of infected virus, bacteria or other particles by cells is called allophagocytosis.Lysosome phagocytosis refers to the formation of membrane wrapped phagosomes after foreign harmful substances are swallowed into cells
Also known as allophagocyte, its substrate is exogenous, that is, extracellular substances absorbed by cells through phagocytosis and pinocytosis.The heterophagy lysosome is actually formed after the fusion of the primary lysosome and endocytosis vesicle.
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The phagocytosis of infected virus, bacteria or other particles by cells is called allophagocytosis.The phagocytosis of lysosomes refers to the formation of membrane wrapped phagosomes after foreign harmful substances are swallowed into cells. The primary lysosomes quickly fuse with the phagosomes to form secondary lysosomes. At this time, the substrate in the lysosomes is taken from outside the cells, so it is a heterophagocytic lysosome. In the heterophagocytic lysosomes, the phagosomes are enzymatically hydrolyzed;After hydrolysis, those soluble small molecules can enter the cytosol through the lysosomal membrane and be reused for cells or discharged as waste.Therefore, the phagocytosis of lysosomes can protect cells from infection by bacteria and viruses, which is necessary for the defense function of cells.
Multicellular animals have specializedPhagocyte, i.emacrophage(macroscopic) andNeutrophils(neutral) is responsible for the protection and defense task in the body.In the process of cell phagocytosis, if liquid is swallowed, it is called endocytosis, and endocytosis vesicles formed by this action also hydrolyze substances in the liquid by fusing with lysosomes.Phagocytosis is also a way for cells to obtain nutrition. Cells wrap some nutrients into the endosome through endocytosis, and finally fuse with the lysosome. Under the action of lysosomal enzymes, the swallowed nutrients are digested to form directly usable small molecules for anabolism.Some single celled organisms obtain nutrition by phagocytosis.
Phagocytosis also includes phagocytosis of senescent and programmed dead cells.If the red blood cells accounting for 1/4 of the total number of adult cells can only survive for 120 days, the human body must eliminate a large number of aging red blood cells every day, which is mainly achieved by phagocytosis, that is, the digestion of lysosomal enzymes.
Phagocytosis is one of the oldest and most basic defense mechanisms of organisms.The target to be eliminated has no specificity, which is called non in immunologySpecific immunityeffect.Neutrophils andmonocyteThe phagocytosis of is very strong,EosinophilsAlthough it has strong mobility, its phagocytosis is weak.White blood cells can seep out of blood vessels through the endothelial space of capillaries and travel in the tissue space.They devour invading bacteria, viruses, parasites and other pathogens and some necrotic tissue fragments.It is generally believed that white blood cells can gather at foreign bodies and engulf them, because white blood cells have chemotaxis.Due to the chemical stimulation produced by bacteria or dead cells, white blood cells are induced to move to this place.Tissue inflammation produces an active polypeptide, which is also one of the inducing substances of leukocyte migration.
The granules in neutrophils are lysosomes, which contain a variety of hydrolases, and can digest the pathogens or other foreign bodies ingested by them.Generally, one white blood cell will die after treating 5~25 bacteria.Dead white blood cell groups and bacterial decomposition products form pus.Monocytes are generated from bone marrow and live in the blood for only 3-4 days, that is, they enter the liver, spleen, lung, lymph and other tissues and transform into macrophages.After becoming macrophages, the volume increases, lysosomes increase, and phagocytosis and digestion ability also increase.However, its phagocytic targets are mainly pathogenic substances entering the cells, such as viruses, malaria parasites and bacteria.Macrophages also participate in activationlymphocyteSpecific immune function.In addition, it also has the function of identifying and killing tumor cells, and clearing away aging and damaged cells.
