CSB332H1 Chapter 4: Chapter 4
Document Summary
Permeability & concentration determine channel conductance: 2 types of electrical signals in nerve cells: Action pots (propagated along entire neuronal: resting pot = steady electrical pot across membrane. (-) = inside of membrane (-) relative to outside membrane pot. Propagate along axons: signalling in ns mediated by changes in, act pots = large brief pulses off depolarization, changes in membrane pot always produced by ion movement. K out or cl in inside more (-), hyperpolarization: rapid ion movement thru ion channels. Ion currents regulated by rate of opening & closing. Perception & analysis of signals, generation of complex motor outputs all depend on ion channel activity. The nerve cell membrane: bilayer 6nm thick, sparingly impermeable to water. Transport molecs (pumps & carriers) move substances against their electrochem grads. Maintain ionic composition of cytoplasm by pumping leaked ions & metabolic substances. What does an ion channel look like: spans membrane, central water-filled pore widens to form vestibule on either membrane side.