BIOL 3202 Lecture Notes - Lecture 9: Pipette, Hair Cell, Threshold Potential
25 Oct 2017
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Document Summary
Ion channels form aqueous pores across the lipid bilayer and allow inorganic ions of the appropriate size and charge to cross the membrane down their electrochemical gradients. Transport through ion channels is at least 1000x faster than through any known transporter protein: most ion channels are gated and open transiently in response to a specific stimulus. An activating stimulus increases the proportion of time the channel spends in the open state: an example of stress-gated ion channels are the ion channels present in stereocilia on auditory hair cells. Sounds vibrations cause these ion channels to be stretched open leading to an influx of cations. This electrical stimulates is transmitted to nerves that carry to the signal to brain where it is decoded as sound: examples of voltage-gated channels are the voltage-gated na+ and k+ channels that conduct nerve impulses along an axon.
