Muscular System:
Neuromuscular Junction

1. What insulates each muscle cell? _________________________

2. Synaptic vesicles in the axon terminal of a motor neuron contain what
neurotranmitter? _________________________

3. An action potential in the axon terminal of a motor neuron opens what type of ion channels? _________________________

4. By what means of membrane transport does the neurotransmitter leave the
axon terminal? _________________________

5. Binding of neurotransmitter to the receptors on the motor endplate open

what type of ion channels? _________________________

6. Opening of these channels leads to _________________________ of the motor endplate.

7. How is the neurotransmitter removed from the synaptic cleft?

8. As a result of question 6, an action potential is propagated along the
_________________________ of the muscle cell and down the _________________________ into the cell.

9. The result of this action potential releases what ion from the terminal cisternae? _________________________

10. a. What effect did molecule "X" in the quiz have on the muscle contraction?

b. Explain its mechanism of action.

c. What drug did molecule "X" act like? _______________

11. a. What effect did molecule "Y" have on the muscle contraction?

b. Explain its mechanism of action.

c. What drug did molecule "Y" act like? _________________________

12. a. What effect did molecule "Z" have on the muscle contraction?

b. Explain its mechanism of action.

c. What drug did molecule "Z" act like? _______________

Muscular System:
Sliding Filament Theory

1. a. The thick filament is composed of what molecule? _________________________

b. Flexing the head of this molecule provides what is known as the _________________________.

2. The cross bridge (myosin head) contains binding sites for what two molecules?

a.

b.

3. Three molecules make up the thin filament.

a. Which molecule has a binding site for myosin cross bridges? _____________________

b. Which molecule covers this binding site? __________________________________________

c. Which molecule has a binding site for calcium ions? ______________________________

4. What molecule must bind to the cross bridge in order for it to disconnect with actin? _________________________

5. Hydrolysis of the molecule in question 4 returns the myosin molecule to the
_________________________ confirmation.

6. Binding of the cross bridges sequentially prevents _____________________ of the
thin filament.

7. Name three roles for ATP in the contraction of muscle.

a.

b.

c.

8. What molecule is connected to the Z line? __________________________________

9. Which of the following shorten during contraction? (may be more than one)

a. Thin filament

b. Sarcomere

c. H zone

d. Thick filament

10. a. What is the name of the condition in which muscles become rigid after
death? _________________________________

b. What is this condition due to?

Muscular System:
Contraction of Whole Muscle

1. Which of the following contract in an all or none fashion?

a. Whole muscle b. Single muscle fiber

2. The development of tension in a muscle, in response to a stimulus above
threshold, is called a _______________________________.

3. Identify the three phases of a muscle twitch from the following definitions:

a. Sarcomeres shorten _______________________________

b. Sarcomeres return to resting length _______________________________

c. Sarcomeres at resting length _______________________________

4. a. Temporal summation results from:

b. In temporal summation, you must ______ (­orØ) the time interval between
stimuli.

5. Below is a list of the five phases of temporal summation. Put in the correct order and describe each stage.

6. In the Motor Unit Summation section, how many motor units were required to lift the weights when:

a. the weight was 160? ______________________

b. the weight was 80? _______________________

7. In the next lab simulation, what was:

a. the threshold stimulus? ______ V

b. voltage when recruitment was obvious? ______ V

c. voltage when all motor units were recruited? ______ V

8. a. In the Length-Tension Relationship experiment, at what degree of stretch
was the maximum tension developed? _______________________________

b. What would congestive heart failure be an example of?
_______________________________