Muscle Contraction Physiology
Quiz
1. The segment of a myofibril that is called a sarcomere runs from
a. one Z line to the next Z line.
b. one I band to the next I band
c. one A band to the next A band
d. one end of the myofibril to the opposite end
2. The __________stores Ca+2 ions, which are released when a muscle is stimulated
to contract.
a. sarcolemma
b. sarcoplasmic reticulum
c. motor end plate
d. axon vesicles
3. In order to stimulate a muscle contraction, a neuron must release a
neurotransmitter at the neuromuscular junction. Where is this chemical released?
a. directly onto the motor end plate
b. into the cytoplasm of the muscle cell
c. into the synaptic cleft
d. throughout the muscle fiber
4. Which of the following statements is true concerning the motor end plate of a
muscle cell?
a. It attaches directly to a motor neuron
b. It provides calcium for actin and myosin
c. It contains receptors for acetylcholine
d. A and C are true
5. Which of the following statements is true concerning the role acetylcholine in
muscle contractions?
a. The chemical provides a stimulus for the muscle to relax.
b. When the chemical attaches to a muscle cell, it sets off a series of events
that allow for muscle contraction.
c. The chemical must be degraded by an enzyme otherwise the muscle will
continue to contract
d. B and C are true
6. The crossbridge formation that allows for a muscle to contract, involves the
connection between
a. neuron and motor end plate
b. tendon to bone
c. calcium to vesicle
d. mysosin to actin
7. What causes the myosin heads to bind to actin?
a. Calcium released by the SR exposes binding sites
b. ADP + P is released pushing the myosin head against the actin
c. Acetylcholine stimulates the binding
d. The myosin head changes shape allowing for binding
8. What causes the actin to be pulled toward the center of the sarcomere?
a. Calcium allows for the pulling action of the myosin head
b. ATP provides energy to the myosin head, which pulls the actin
c. Actin uses ADP and P to move towards the center of the sarcomere
d. A and C are true
9. Which molecule allows for crossbridge reformation by breaking the myosin and
actin crossbridge?
a. Calcium
b. Acetylcholinestarase
c. Acetylcholine
d. ATP
10. A specialized intercellular connection between a neuron and a skeletal muscle
fiber is called a _____________.
a. Neuromuscular junction
b. Synaptic bulb
c. Motor end plate
d. Synaptic cleft
Match the correct description to the event being shown in the diagram.
11.
15.
12.
14.
13.