GCC Neuromuscular Junction Question

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Chapter 9

Muscular System: Neuromuscular Junction

1.Where Calcium stores in each muscle cell? _________________________

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

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 end plate opens what type of ion channels? _________________________

6.Opening of these channels leads to _________________________ of the motor end plate.

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

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

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

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 myosin head contains binding sites for what two molecules?

1.

2.

3.Three molecules make up the thin filament.

a. Which molecule has a binding site for myosin heads? _____________________

b. Which molecule covers this binding site? __________________________________________

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

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

5.Breaking down of ATP or ___________of the ATP returns the myosin molecule to the high energy conformation.

6.Binding of the __________heads sequentially prevents backsliding of the thin filament.

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

1. _________________________

2. _________________________

3. _________________________

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. SR

d. thick filament

Muscular System: Contraction of Motor Units

1.Define a motor neuron: _______________________________________________________________________________________________________________________________________________ _________

2.Define a motor unit: __________________________________________________________________________________________________________________________________________________________

3.The synapse between a motor neuron and the muscle it innervates is called a/an __________________________.

4. The stimulation of additional motor units will increase the strength of the contraction. This process is called _______________________.

5.The muscles of the eye need to make precise small motor movements. Therefore, you would find________ (large or small) motor units in the eye.The muscles of the thigh exhibit gross movements for walking. Therefore, you would find_______ (large or small) motor units in the thigh.

6.a. How is muscle tone maintained in the muscle? ____________________________________________________________________________________________________________________

b. If the nerve to a muscle is cut, what will happen to the muscle? _______________________________________________________________________________________________________ ___________

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/an _______________________________.

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

1. Sarcomeres shorten _______________________________

2. Sarcomeres return to resting length _______________________________

3. Sarcomeres at resting length _______________________________

4.a. Summation results from: _________________________________________________________________________________________________________________________________________

b. In summation, you must __________ (Increase or decrease)the time interval between stimuli.

5.Below is a list related to summation. Put them in the correct order and describe each

stage.

Order	Stage	Description
	Fatigue
	Incomplete tetanus
	Treppe
	Complete tetanus

6.In the Motor Unit related section, how many motor units (many or few) were required to lift the weights when:

a. the weight is very heavy (~50 lbs)? ______________________

b. the weight was (~20 lbs)? _______________________