PHGY 209 Lecture Notes - Lecture 19: Hydrolysis, Phosphorylation, Skeletal Muscle
Document Summary
Factors affecting movement across the cell membrane include: Availability and number of carriers and ion channels. Active (energy dependent: carrier-mediated active transport, primary, secondary, pino/phagocytosis. Diffusion: movement of solute particles resulting from random thermal molecular motion; as they collide, they become dispersed, net flux of solute particles always occurs from a region of high concentration to one of lower concentration. At equilibrium, diffusion fluxes in opposite directions are equal, i. e. the net flux equals zero. Diffusion occurs even in the presence of a mechanical partition (membrane) as long as it is permeable to diffusing particles. The rate of diffusion may be calculated by fick"s law of diffusion. J net flux: net movement of molecules across a membrane. P permeability (or diffusion) coefficient: a constant based on the ease with which a molecule moves through a membrane. A surface area of the membrane (c0 ci) concentration gradient of the diffusing molecule across the membrane.