Homework 3
The Muscular System: Neuromuscular Junction
1. What insulates each muscle cell? __________endomysium_______________
2. Synaptic vesicles in the axon terminal of a motor neuron contain what
neurotransmitter? __________acetylcholine_______________
3. An action potential in the axon terminal of a motor neuron opens what type
of ion channels? ____________Voltage-gated Calcium_____________
4. By what means of membrane transport does the neurotransmitter leave the
axon terminal? ____________exocytosis_____________
5. Binding of neurotransmitter to the receptors on the motor endplate open
what type of ion channels? ___________chemically-gated______________
6. Opening of these channels leads to ______depolarization_________ of the motor endplate.
7. How is the neurotransmitter removed from the synaptic cleft?
Acetylcholine diffuses away from the receptor and is broken down by acetylcholinesterase
8. As a result of question 6, an action potential is propagated along the
________sarcolemma_________ of the muscle cell and down the _______T tubules________
into the cell.
9. The result of this action potential releases what ion from the terminal
cisternae? ____Ca²⁺____
10. a. What effect did molecule “X” in the quiz have on the muscle contraction?
Molecule x blocked the ion channel receptor site so acetylcholine could not attach therefor not allowing the muscle to ultimately contract.
b. Explain its mechanism of action.
When the secretory vesicles opened to allow acetylcholine to enter the synaptic cleft Molecule X rushed into the synaptic cleft. Molecule X moved faster than Acetylcholine therefore binding to the receptor sites first.
c. What drug did molecule “X” act like? _______curare________
11. a. What effect did molecule “Y” have on the muscle contraction?
Molecule Y prevented break down of
1. What insulates each muscle cell? __________endomysium_______________
2. Synaptic vesicles in the axon terminal of a motor neuron contain what
neurotransmitter? __________acetylcholine_______________
3. An action potential in the axon terminal of a motor neuron opens what type
of ion channels? ____________Voltage-gated Calcium_____________
4. By what means of membrane transport does the neurotransmitter leave the
axon terminal? ____________exocytosis_____________
5. Binding of neurotransmitter to the receptors on the motor endplate open
what type of ion channels? ___________chemically-gated______________
6. Opening of these channels leads to ______depolarization_________ of the motor endplate.
7. How is the neurotransmitter removed from the synaptic cleft?
Acetylcholine diffuses away from the receptor and is broken down by acetylcholinesterase
8. As a result of question 6, an action potential is propagated along the
________sarcolemma_________ of the muscle cell and down the _______T tubules________
into the cell.
9. The result of this action potential releases what ion from the terminal
cisternae? ____Ca²⁺____
10. a. What effect did molecule “X” in the quiz have on the muscle contraction?
Molecule x blocked the ion channel receptor site so acetylcholine could not attach therefor not allowing the muscle to ultimately contract.
b. Explain its mechanism of action.
When the secretory vesicles opened to allow acetylcholine to enter the synaptic cleft Molecule X rushed into the synaptic cleft. Molecule X moved faster than Acetylcholine therefore binding to the receptor sites first.
c. What drug did molecule “X” act like? _______curare________
11. a. What effect did molecule “Y” have on the muscle contraction?
Molecule Y prevented break down of