PHAR 426: lecture 1 - neuroanatomy and physiology: electrical activity in brain

action potential happens when

change in flow of ions across cell membrane

conduction velocity

speed action potential propagates down nerve

Channels involved in AP

Voltage gated Na channel, VGKC, VGCC

how is resting membrane potential maintained

through K selective channels (leak channel)

how is AP made

depolarization inside cell reaches 7-15 mV positive of resting potential

what happens when AP is triggered

VGNaC opens and depolarized to +100 mV

after Na depolarization

VGNaC closes and K channel opens to bring back to resting potential

refractory periods of Na channels

absolute and relative

absolute refractory period

no stimulus can excite nerve fiber; aprox. 2/3 of time width of AP

relative refractory period

stronger than normal stimulus can trigger a second AP; last third of AP time

Chemical synapses

neurotransmitter vesicles release into synaptic cleft to post synaptic receptors on dendrite/soma

synaptic release is

calcium dependent; requires docking proteins

botox targets

docking proteins

docking proteins are

slow to replace

post synaptic inhibition

GABA (inhibitory transmitters) acting on soma/dendrite

presynaptic inhibition

increase Cl conductance = smaller AP, VGKC open = decreased Ca influx, direct inhibition of transmitter release