Chapter 10 (Muscular Tissue VII)

Question 1

Neuromuscular junction (NMJ)

Answer 1

Motor neurons have a threadlike axon that extends from the brain or spinal cord to a group of muscle fibers
Action potentials arise at the interface of the motor neuron and muscle fiber

Question 2

Synapse

Answer 2

Where communication occurs between a somatic motor neuron and a muscle fiber

Question 3

Synaptic cleft

Answer 3

Gap that separates the two cells

Question 4

Neurotransmitter

Answer 4

Chemical released by the initial cell communicating with the second cell

Question 5

Synaptic vesicles

Answer 5

Sacs suspended within the synaptic end bulb containing molecules of the neurotransmitter acetylcholine (Ach)

Question 6

Motor end plate

Answer 6

The region of the muscle cell membrane opposite the synaptic end bulbs
Contain acetylcholine receptors

Question 7

Nerve impulses elicit a muscle action potential:

Answer 7

Release of acetylcholine
Activation of ACh receptors
Production of muscle action potential
Termination of ACh activity

Question 8

Release of acetylcholine

Answer 8

Nerve impulse arriving at the synaptic end bulbs causes many synaptic vesicles to release ACh into the synaptic cleft

Question 9

Activation of ACh receptors

Answer 9

Binding of ACh to the receptor on the motor end plate opens an ion channel
Allows flow of Na+ to the inside of the muscle cell

Question 10

Production of muscle action potential

Answer 10

The inflow of Na+ makes the inside of the muscle fiber more positively charged triggering a muscle action potential
The muscle action potential then propagates to the SR to release its stored Ca++

Question 11

Termination of ACh activity

Answer 11

Ach effects last only briefly because it is rapidly broken down by acetylcholinesterase (AChE)