Studied by 8 people
depolarization of membrane to threshold
rapid opening of voltage-gated Na+ channels
Na+ entry causes rapid depolarization
Voltage-gated Na+ channels inactivate
Voltage-gated K+ channels open
K+ exits cell causes rapid repolarization
after-hyperpolarization due to K+ efflux
voltage-gated K+ channels close and the membrane returns to its resting value
steps of the action potentials
contains voltage-gated channels that respond to local electrical changes
axon
the depolarization phase is characterized by __________
rapid sodium entry
the repolarization phase is accelerated by _________
potassium efflux
voltage-gated potassium channels reach peak permeability, part of absolute refractory period
repolarization phase
potassium channels still open, inactivation gate on sodium channels opens, relative refractory period - cell is hyperpolarized, so requires greater stimulus to reach threshold
hyperpolarization phase
potassium permeability reduced, membrane potential goes back to resting value
after-hyperpolarization phase
T or F, open sodium channels accelerate the repolarization phase of an action potential
false
involves entire membrane surface, proceeds in series of small steps, occurs in muscle and unmyelinated axons
continuous conduction
involves patches of membrane exposed at nodes AP leads from node to node, proceeds in series of large steps, occurs in myelinated axons
saltatory conduction
action potential is 'recharged' at each membrane segment by fresh flow of Na+ through newly opened voltage-gated channels in the neighboring membrane
action potential propagation
______ axons = faster action potential propagation
wider
myelin produced by Schwann cells and oligodendrocytes, acts as electrical insulation
myelination
neurotransmitters released from the axon terminal of the pre-synaptic cell bind to receptors on the post-synaptic cell often ligand-gated channels which results in a change in the membrane potential of the post-synaptic cell
chemical synapses
Note 
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