ISCI 2A18 Lecture Notes - Lecture 3: Serca, Nicotine, Nicotinic Acetylcholine Receptor
6 Dec 2016
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Document Summary
Cells selectively and dynamically control the movement of ions to create/shape: electric potential difference across membrane, vrest gives magnitude and sign. Resting membrane potential (vrest) separation of charge creates an of this difference when the cell is at rest (not signaling), inside of cell is ve. Generator (sensory) potential seen in cells that may or may not be with respect to outside, order of magnitude generally 10s of millivolts neurons, ex. photoreceptors. To set up a potential difference, the barrier must have selective permeability to charged particles. For neurons, the relevant charged particles are na+, k+, and cl- ions, which are controlled by transporters and ion channels. Driven by atp, concentration gradient (co-/anti-transport), ph. Speed limited by protein conformational change (~103-106 ions/sec) Speed limited by diffusion (as high as ~108 ions/sec) Ions passively diffuse no flux against concentration gradient. Maintains cell volume generally, and volume in neurons uses ~20-30% of.
