NROSCI 0081 Lecture Notes - Lecture 8: Myelin, Axon Hillock, Potassium Channel
31 Jan 2018
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Document Summary
Through semipermeable membrane: cell membranes permit some substances to pass through but not others. Potential: ions on the inside are different from the outside. Membrane potential: equilibrium potential (equal number of positive and negative ions) The membrane of a cell is selective about what it lets in. It likes small molecules (oxygen) and fat-soluble molecules (nonpolar, anesthetics) but not large or charged particles. If you (cid:272)a(cid:374)"t get through the (cid:373)e(cid:373)(cid:271)ra(cid:374)e, you (cid:374)eed a (cid:272)ha(cid:374)(cid:374)el. Ions are atoms with extra electrons or missing electrons giving them a positive or negative charge. Voltage-gated channels: open when the electrical potential changes. Potassium can go in whenever it wants (open channel) Proteins are negatively charged and pull in potassium. Potassium also goes out because of diffusion. Chloride (cl-) leaks inside in small amounts. Sodium wants inside so it sneaks in through the potassium channel. Potassium-sodium (k+ - na+) pump: takes up a lot of energy, kicks 3 na+ out and lets 2.
