Cellular Neurobiology Flashcards
Resting membrane potential
separation of charge across the membrane which creates an electrical potential. Ions unevenly distributed
Membrane has channels that
allow movement of ions across it, generating current
Channel
transmembrane protein that forms a pore in the membrane; can be gated or non-gated
Outward current
+ ions out
Inward current
+ ions in
Movement across membrane determined by
chemical (concentration gradient); electrical (potential difference)
@ rest K
[] out and voltage in. Overall out
Action potential
a membrane depolarization that propagates along the axon and conducts the electical signal from the cell body to the axon terminals
The “threshold” for action potential generation is the
depolarization, at which voltage-gated Na channels are activated.
suprathreshold depolarizatons followed by
activation of VG Na channels (influx). Na channels inactivate and VG K channels open. N/K ATPase restores gradients
Use dependent blockers of VG Na channels are used as
anti-epileptic drugs
In demyelinating disorders, VG K channels are redistributed along the internodes of the axons, causing
conduction abnormalities; channel blockers are under development
Synaptic ultrastructures
presynaptic nerve terminal, synaptic cleft, postsynptic element
synaptic cleft contains
glycoprotein linking material and is surrounded by glial cell processes.
Common presynaptic arrangements
terminal enlargements (boutons), varicosities (in passing), neuromuscular synapse/motor end plates
Synaptic type: axodendritic
axon terminal branch (presynaptic) synapses on a dendrite
Synaptic type: axosomatic
axon terminal branch synapses on a soma (cell body)
Synaptic type: axoaxonic
axon terminal branch synapses on another axon terminal branch (for presynaptic inhibition) or beside the initial segment of an axon
Synaptic type: dendrodendritic
dendrite synapsing on another dendrite (very localized effect)
