Human Anatomy and Physiology Laboratory Manual, Cat Version: Anatomy and Physiology Lab Flashcards
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selective or differential permeability
the plasma membrane is selective about what passes through it, it allows nutrients to enter the cell but keeps out undesirable substance. by the same toke, valuable cell proteins and other substances are kept within the cell, and excreta or wastes pass to the exterior.
passive processes
transport through the plasma membrane based on concentration or pressure differences driving the movement. Two important processes: diffusion and filtration.
active processes
transport through the plasma membrane by the cell providing energy (ATP) to power the transport process. two types: active transport, and vesicular transport
diffusion
passive molecular movement from an area of higher concentration to an area of lower concentration
concentration gradient
regional differences in the concentration of a particular substance
simple diffusion
the unassisted diffusion of solutes through a selectively permeable membrane
facilitated diffusion
the passive movement of a substance across a plasma membrane by means of a protein carrier
osmosis
the flow of water across a selectively permeable membrane from one solution to another solution that contains a higher solute concentration
isotonic solutions
cells retain their normal size and shape in isotonic solutions (same solute/water concentration as inside cells; no net osmosis).
hypertonic
cells lose water by osmosis and shrink in a hypertonic solution (contains a higher concentration of solutes than are present inside the cells)
hypotonic
cells take on water by osmosis until they become bloated and burst (lyse) in a hypotonic solution (contains a lower concentration of solutes than are present in cells)
crenation
cellular shrinkage due to an osmotic movement of water out of the cytoplasm
filtration
a passive process in which water and solutes are forced through a membrane by hydrostatic (fluid) pressure. filtration in not selective
active transport
the ATP-dependent absorption or secretion of solutes across a plasma membrane
vesicular transport
fluids containing large particles and macromolecules are transported across cellular membranes inside membranous sacs called vesicles. vesicular transport moves substances into the cell (endocytosis) and out of the cell (exocytosis).
endocytosis
the movement of relatively large volumes of extracellular material into the cytoplasm via the formation of a membranous vessel at the cell surface, 3 types phagocytosis, pinocytosis, and receptor-mediated endocytosis
phagocytosis (cell-eating)
the cell engulfs some relatively large or solid material such as a clump of bacteria, cell debris, or inanimate particles. When a particle binds to receptors on the cell's surface, cytoplasmic extensions called pseudopods form and flow around the particle. this produces an endocytotic vesicle called a phagosome.
pinocytosis (cell drinking)
also called fluid-phase endocytosis, the cell "gulps" a drop of extracellular fluid containing dissolved molecules.
receptor-mediated endocytosis
the main mechanism for specific endocytosis of most macromolecules, the receptors for this process are plasma membrane proteins that bind only certain substances
exocytosis
a vesicular transport process that ejects substances from the cell into the extracellular fluid. the substance to be removed from the cell is first enclosed in a protein-coated vesicle called a secretory vesicle.