BIOL 2021 Lecture Notes - Lecture 5: Voltage-Dependent Calcium Channel, Exocytosis, T-Tubule
12 May 2013
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Lecture 5: chapter 11 gated ion channels. Sound makes pressure waves and the stereocilia tilt and that pulls on the filament, pulling ion channels: action potential. Voltage difference in electrical charge across a membrane. 100mv = 1/100 000 k+ in cytosol. Na+/k+ atpase = 10% of potential: 3 na+ : 2 k+ 90% comes from k+ leak channels: open k+ channel, allows equilibration across the channel. K+ inside = 140 mm, k+ outside = 5mm: v = -89mv. Previous cells axon terminals synapse dendrite axon terminals synapse Ends don"t touch, they meet at a synapse: space between is synaptic cleft. Presynaptic cell, synaptic cleft, post synaptic cell. Signal is a neurotransmitter: fusion event, binds to ligand gated ion channels (ligand is the neurotransmitter) Example: acetylcholine gated: allow na+ into the cell. Depolarizaton = decrease in negative membrane potential flows toward zero. Na+ channel, opens in response to depolarization: action potential, voltage gated na+ channel. Closed open inactivated (can"t be opened)
