Ch 10: 3-D Physiology Assignment: The Neuromuscular Junction

Skeletal muscle can contract without nerve stimulation. True False

False

What happens to the neurotransmitter once an action potential is propagated on the muscle sarcolemma? -It remains attached to the muscle cell until it eventually wears away. -It enters the muscle cell where it is used to produce ATP. -It decomposes on its own within 30 seconds. -It is immediately broken down by an enzyme.

It is immediately broken down by an enzyme.

By what process does the motor neuron stimulate the muscle cell? The motor neuron changes shape putting pressure on the muscle cell to trigger contraction. -The action potential skips directly from the motor neuron onto the muscle cell. -Neurotransmitter is released into the synaptic cleft to cause an action potential in the muscle cell. -The motor neuron creates a magnetic resonance which stimulates myofibrils to react.

Neurotransmitter is released into the synaptic cleft to cause an action potential in the muscle cell.

A single action potential will create a single momentary contraction, not a continuous contraction. -True -False

True

The function of the neurotransmitter is to cause the opening of sodium channels in the muscle cell membrane. -True -False

True

The opening of sodium channels is essential for the initiation of an action potential in the muscle cell membrane. True False

True

The neurotransmitter released by the motor neuron to cause muscle contraction is -serotonin. -dopamine. -epinephrine. -acetylcholine.

acetylcholine.

When the electrical impulse of the motor neuron reaches the synapse, the release of neurotransmitter is caused by -an increase in intra-cellular calcium when voltage-gated calcium channels open. -the opening of electrically sensitive pores in the motor neuron. -the electrical activation of pumps in the synaptic cleft. -the temporary electrical breakdown of the neuromuscular junction.

an increase in intra-cellular calcium when voltage-gated calcium channels open.

The impulses that initiate muscle contraction originates in the -joint associated with the specific muscle. -brain or spinal cord. -tendons attached to the ends of the muscle. -muscle itself.

brain or spinal cord.

A group of muscle cells stimulated by a single motor neuron is known as a -contractile structure. -myofibril. -motor unit. -neuron divergence.

motor unit.