 | Term | Definition |
| |
selectively permeable membrane |
such as plasma membrane; allows only specific substances to pass |
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hypertonic |
solute with higher concentration of solutes |
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hypotonic |
solute with lower concentration of solutes |
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isotonic |
solute with equal concentration of solutes |
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bulk flow |
collective movement of substances in the same direction in response to a force or pressure. blood moving through a blood vessel is this |
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passive transport |
describes movement of substances from regions of higher to lower concentrations/don't require expenditure of energy |
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simple diffusion (diffusion) |
net movement of substances from area of high concentration to one of lower; occurs as result of random/constant motion characteristics of all molecules, motion that is independent from the motion of all molecules; state of equilibrium is reached where molecules are uniformly distributed but continue to move randomly |
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osmosis |
diffusion of water molecules across a selectively permeable membrane. when water moves into body by this process, hydrostatic pressure (osmotic) may build up inside body |
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dialysis |
diffusion of solutes across a selectively permeable membrane |
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plasmolysis |
movement of water out of a cell that results in collapse of cell |
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facilitated diffusion |
diffusion of water/solutes through channel proteins in plasma membrane. |
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countercurrent exchange |
diffusion of substances b/w two regions in which substances are moving by bulk flow in opposite directions; water flow through fish gills/diffusion of oxygen from water to blood |
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active transport |
movement of solutes against a gradient and requires expenditure of energy (ATP usually); transport proteins in plasma membrane transfer solutes such as small ions, amino acids, and monosaccharides across membranes |
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vesicular transport |
uses vesicles/other bodies in cytoplasm to move macromolecules/large particles across membrane |
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exocytosis |
process of vesicles fusing with plasma membrane/ releasing contenets to outside of cell |
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endocytosis |
capture of a substance outside cell when plasma membrane merges to engulf it; substance enters cytoplasm enclosed in vesicle |
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phagocytosis |
occurs when undissolved material enters cell. plasma membrane wraps around solid material and engulfs it, forming phagocytic vesicle |
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Pinocytosis |
occurs when dissolved substances enter cells; plasma membrane folds inward to form channel allowing liquid to enter. plasma membrane closes off channel, encircling liquid inside vesicle |
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receptor mediated endocytosis |
form of pinocytosis that occurs when specific molecules in fluid surrounding cell bind to receptors that concentrate in coated pits in plasma membrane; the pits, receptors, and molecules (ligands) fold inward and formation of vesicle follows |
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ligands |
specific molecules in the fluid surrounding the cell |
