PSL300H1 Final: summary of all lectures.doc
Document Summary
Lecture 2: first step in generating a membrane potential (voltage) is to create a concentration gradient in specific ion species. Atpases i. e. na+/k+, ca2+ generate concentration gradient across cell membrane: second step is to make membrane semi-permeable so that one ion specie can cross the membrane. It can diffuse down its concentration gradient building up a charge towards the size i t"s moving towards (creates an electrical gradient: for the first step, na+/k+ pump mainly used. 3 na+ moves outward, 2 k+ move in: so it"s more efficient for na than k: k is more concentrated inside cell, and na outside, extremely important in maintaining the viability of the cells. 1/3 of the metabolic energy consumed goes to the pump. K diffuses out through these pores and accumulates on the outer surface (passive diffusion down the concentration gradient). The na/k pump pumps it back into the cell.
