PSY290H5 Lecture Notes - Lecture 4: Antibody, Neurotransmitter, Axon Hillock
Document Summary
Integration of postsynaptic potentials and generation of action potentials occurs at the initial axonal segment: voltage-gated channel- 2 types. 45 mv is threshold to open the channel. Takes less than 1 ms o o o o. Action potential rising phase occurs because the o neuronal membrane contains voltage-gated na+ channels that open in a regenerative manner if depolarization passes the threshold level o. Action potential rising phase ends because the o voltage-gated na+ channels inactivate. Action potential falling phase occurs because the o voltage-gated k+ channels open (with a delay) in response to depolarization: closed, open up under right conditions. Refractory period: time in which no action potential will occur, regardless of what happens: peak of action potential= absolute refractory period. As soon as voltage-gated sodium channels open: soon after peak of potential, potassium pump opens (another ap could occur but the active leaving of k creates hyperpolarization, relative refractory period= when potassium channels open.
