PASSIVE TRANSPORT (2PAGE) TO COMBIT
Diffusion increases as the size of the pore increases in the cell membrane accumulation of calcium effectively decreases pore size and slows down the diffusion rates of positively charged ions the transport of o2 co2 glucose etc from the blood through capillary wall interstitial fluid and cell membrane occurs through diffusion
2. osmosis is the diffusion of water across a selectively semipermeable cell membrane from lower concentration to higher concentration its passage depends on a concentration grandient and is directly related to the number of particles per volume of fluid (osmotic pressure) on either side of the membrane
mediated transport
facilitated diffusion is the movement of a substance through a cell membrane assisted by a carrier that passively but specifically transport the substance it is saturable and energy independent substance like glucose some aminoacids and vatamins are transported by facilitated diffusion at the rate faster than simple diffusion carrier is a protein which specifically combines with the substance on one side of membrane and carries it to drop it off to other glut -1 and glut-4 are the classical examples of glucose transporters substance of similar structures may compete with each other for the same carrier under these conditions the rate of transport may be reduced
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