chapter 7 Flashcards
alpha motor neurons
lower motor neurons w/cell bodies in the ventral/anterior horns of spinal cord
neuromuscular junction
the synapse between motor neurons + skeletal muscle
what type of receptor does ACH bind to?
nicotinic receptors
what kind of channel is nicotinic ACH receptors?
ligand-gated channels
motor endplate
nerve fibers branching terminals invaginates the surface of the muscle cell
synaptic gutter/trough
the invaginated cell membrane
synaptic space/cleft
the space between the nerve terminal and the muscle fiber membrane
how wide are the synaptic space/cleft?
20-30 nanometers
subneural clefts
smaller folds in the muscle membrane at the bottom of the gutter function to increase the surface area for NT action
choline acetyltransferase
assembles acetyl CoA + choline into ACH
acetylcholinesterase
breaks ACH down into acetate + choline
dense bars
on the inside surface of the neuron + connected to transmembrane protein particles that are voltage gated calcium channels
what kind of channels are situated deep in subneural clefts?
voltage gated sodium channels
ACH receptors subunits (5)
2 alpha subunits bind to 2 molecules of ACH, beta subunits, delta subunits, + gamma subunits in kids/epsilon subunits in adults
end plate potentials
local current created by the influx of sodium through ACH gated channels
nerve resting membrane potential
-65 to -70mV
muscle resting membrane potential
-80 to -90mV
nerve action potential duration
less than 1 millisecond
muscle action potential duration
1-5 milliseconds
nerve AP conduction of velocity
70-120 m/sec
muscle AP conduction of velocity
3-5 m/sec
myasthenia gravis
autoimmune disease that causes muscle weakness bc neuromuscular junction is unable to transmit enough signals from nerve fibers to muscle fibers
