Search results
Results from the WOW.Com Content Network
Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested materials. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating). It is a form of ...
In humans, this process occurs primarily for absorption of fat droplets. In endocytosis the cell plasma membrane extends and folds around desired extracellular material, forming a pouch that pinches off creating an internalized vesicle. The invaginated pinocytosis vesicles are much smaller than those generated by phagocytosis.
Endocytosis is when a cell absorbs a molecule, such as a protein, from outside the cell by engulfing it with the cell membrane. It is used by most cells, because many critical substances are large polar molecules that cannot pass through the cell membrane. The two major types of endocytosis are pinocytosis and phagocytosis.
In pinocytosis, cells engulf liquid particles (in humans this process occurs in the small intestine, where cells engulf fat droplets). [39] In phagocytosis, cells engulf solid particles. [40] Exocytosis involves the removal of substances through the fusion of the outer cell membrane and a vesicle membrane. [41]
Phagocytosis (from Ancient Greek φαγεῖν (phagein) 'to eat' and κύτος (kytos) 'cell') is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is called a phagocyte.
Pinocytosis ("cell drinking") is essentially the same process, the difference being that the substances ingested are in solution and not visible under the microscope. [18] Phagocytosis and pinocytosis are both undertaken in association with lysosomes which complete the breakdown of the material which has been engulfed. [19]
Phagocytosis of an otherwise-viable cell may occur because the cell is recognised as stressed, activated, senescent, damaged, pathogenic or non-self, or is misrecognised. Cells are phagocytosed as a result of: i) expressing eat-me signals on their surface, ii) losing don’t-eat-me signals, and/or iii) binding of opsonins .
However, to obtain energy from its outside environment, cells must not only retrieve molecules from their surroundings but also break them down. [1] This process is known as intracellular digestion. [1] In its broadest sense, intracellular digestion is the breakdown of substances within the cytoplasm of a cell.