Page 339 - Fundamentals of anatomy physiology

Spotlight Figure 10–9
Events at the Neuromuscular Junction

A single axon may branch to control more than one skeletal Motor neuron
muscle fiber, but each muscle fiber has only one neuromus-
cular junction (NMJ). At the NMJ, the axon terminal of the Path of electrical impulse
neuron lies near the motor end plate (action potential)
of the muscle fiber.
Axon

Neuromuscular
junction

Axon
terminal

SEE BELOW

Sarcoplasmic Motor
reticulum end plate

Myofibril Motor end plate

1 The cytoplasm of the axon 2 The stimulus for ACh release

terminal contains vesicles filled is the arrival of an electrical
with molecules of acetylcholine, impulse, or action potential,
or ACh. Acetylcholine is a at the axon terminal. An action
neurotransmitter, a chemical potential is a sudden change in
released by a neuron to change the membrane potential that
the permeability or other travels along the length of the
properties of another cell’s plasma axon.
membrane. The synaptic cleft and
the motor end plate contain Arriving action
molecules of the enzyme potential
acetylcholinesterase (AChE),
which breaks down ACh.

Vesicles ACh

The synaptic cleft is a Junctional AChE
narrow space that fold of
separates the axon motor end plate

terminal of the neuron
from the opposing motor

end plate.

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