BIO 1140 Lecture Notes - Lecture 4: Active Transport, Troponin, Exocytosis
Document Summary
Membrane potential: a way to measure the difference in overall charge in either size of the (cid:373)e(cid:373)(cid:271)ra(cid:374)e (cid:894)(cid:373)v(cid:895). Whe(cid:374) the (cid:373)e(cid:373)(cid:271)ra(cid:374)e is at rest (cid:894)(cid:272)ell is(cid:374)"t (cid:272)o(cid:373)(cid:373)u(cid:374)i(cid:272)ati(cid:374)g, (cid:272)o(cid:374)(cid:272). Gradie(cid:374)t is constant) means the net change in conc. is none. For most cells, resting membrane potential will be (-60) (-90(cid:895) (cid:373)v. that"s (cid:271)e(cid:272)ause ethers a differe(cid:374)(cid:272)e i(cid:374) (cid:272)o(cid:374)(cid:272)e(cid:374)tratio(cid:374) of differe(cid:374)t io(cid:374)s o(cid:374) the inside and on the outside. Most cells have more potassium on the inside, and a lot more sodium on the outside. Chloride ions and calcium ions are taken into account for overall charge. Membrane is not permeable for ions in general. The membrane is more permeable to potassium than sodium which contributes to the difference in overall charge across the membrane. When a cell becomes stimulated because ligand gated are open or something has triggered the entry of exit of ions, that overall concentration of both sides will change so overall membrane potential will change.