Neuromuscular Junction Flashcards
The neurons that stimulate skeletal muscle fibers to contract are called
somatic motor neurons
A muscle fiber contracts in response to one or more __________ propagating along its sarcolemma and through its system of T tubules.
action potential
Muscle action potentials arise at the __________, the synapse between a somatic motor neuron and a skeletal muscle fiber.
Neuromuscular junction
A __________ is a region where communication occurs between two neurons, or between a neuron and a target cell.
synapse
At most synapses, a small gap called the __________ separates the two cells.
Synaptic cleft
Because the cells do not physically touch, the action potential cannot ‘jump the gap.’ Instead, the first cell communicates with the second by releasing a chemical messenger called a __________.
Neurotransmitter
The end of the motor neuron at the NMJ is called the __________.
Axon terminal
The axon terminal divides into a cluster of __________ at the NMJ.
Synaptic end bulbs
Suspended in the cytosol within each synaptic end bulb are membrane-enclosed sacs called __________, which contain molecules of __________.
synaptic vesicles, acetylcholine (ACh)
The neurotransmitter released at the neuromuscular junction (NMJ) is __________.
Acetylcholine
The region of the sarcolemma opposite the synaptic end bulbs is called the __________, which is the muscle fiber part of the NMJ.
Motor end plate
The motor end plate contains 30 million to 40 million __________, which are integral transmembrane proteins that bind specifically to __________.
A: acetylcholine receptors, acetylcholine (ACh)
Acetylcholine receptors are located in the __________ of the motor end plate, providing a large surface area for ACh.
Junctional folds
Acetylcholine receptors are __________ ion channels.
Ligand-gated
A neuromuscular junction includes all of the __________ on one side of the synaptic cleft, and the __________ on the other side.
synaptic end bulbs, motor end plate
