Motor and sensory nerves are classified as somatic nerves.
Motor neurons originate in the anterior horn of the
Basic neurologic anatomy spinal cord. Motor nerve are efferent neurons.
Sensory neurons carry action potentials to the spinal cord via
the dorsal horn. Sensory neurons are afferent neurons.
Discuss the anatomy of the 3 components include the motor nerve terminal, synaptic
neuromuscular junction cleft, and motor end-plate or post-synaptic membrane
(NMJ)
1. The motor nerve action potential arrives at and
Final Exam Review depolarizes the nerve terminal.
Discuss the steps of 2. Depolarization causes voltage-
neuromuscular transmission. gated calciumchannels to open.
3. Calcium diffuses down a
concentration gradientinto the
nerve terminal.
4. Inside the nerve terminal, influx
of calcium causesvesicles
containing Aches to fuse with the
nerve cell membrane and open to
the exterior.
5. ACh spills out into the synaptic
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, cleft (exocytosis) 6. Presynaptic
nicotinic receptors respond to ACh
by increasing the synthesis and
release of Ash (positive feedback
response)
7. ACh diffuses down a
concentration gradient fromthe
presynaptic membrane to the
motor endplate of the
postsynaptic membrane.
8. ACh combines with nicotinic
receptors of theprotein channel at
the postsynaptic membrane.
9. When both of the alpha
subunits of the nicotinicreceptor
channel are occupied by ACh, the
channel snaps open. 2 ACh
molecules are needed to open
each nicotinic acetylcholine
receptor.
10. Sodium and calcium ions
diffuse into the musclecell
through the channel while
potassium ions diffuse out to the
extracellular space.
11. With ion diffusion, electrical
threshold is reached,and an action
potential is initiated.
12. The action potential sweeps
across the skeletalmuscle cell and
triggers muscle contraction.
Discuss the membrane
potential in millivolts
compared to milliseconds the voltage across a cell's plasma membrane
What breaks down Acetylcholinesterase (AChE), also known as "true"
acetylcholine? cholinesterase (type I cholinesterase)
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