Anatomy & Physiology
Mrs. Edgerton 2007-08
Name __________________________
Block _______ Date _______________
Muscular System Study Guide
Answer the following questions in the space provided.
1. Label the components of the neuromuscular junction represented below to learn the events of
synaptic or neuromuscular transmission. Here are the things you need to label:
a. Nerve axon
b. Presynaptic and postsynaptic membranes
c. Entrance of Ca through channels
d. Release of transmitter
e. Diffusion of transmitter across gap
f. Binding of transmitter to receptors
g. Production of EPSPs and action potentials
h. Breakdown and recycling of transmitter
2 . A synapse won't work unless the various parts are in the right location. Tell where these parts of the
synapse are located (presynaptic side, postsynaptic side, synaptic cleft):
a. Receptor proteins - _____________________________________________________________________
b. Transmitter vesicles - ___________________________________________________________________
c. Enzyme which breaks down the transmitter - ________________________________________________
d. Pump which recycles the transmitter - ______________________________________________________
e. Ca2+ channels - _________________________________________________________________________
3. Give a disease or toxin which inhibits each of these parts of the synapse or neuromuscular junction:
a. Transmitter deficiency: __________________________________________________________________
b. Release of transmitter: __________________________________________________________________
c. Receptors: ____________________________________________________________________________
d. Recycling of transmitter: _________________________________________________________________
e. Breakdown of transmitter: _______________________________________________________________
4. On the diagram of the sarcomere below label the A band, the I band, the Z lines and the proteins actin and
myosin. To the right redraw the sarcomere, showing what happens when it contracts.
5. Look at your drawing of the contacted sarcomere.
a. What happens to the Z lines? _____________________________________________________________
b. What happens to the A band? ____________________________________________________________
c. What happens to the I band? _____________________________________________________________
6. Calcium has 2 roles in the stimulation and contraction of muscle. What are they? (Hint: don't forget the
neuromuscular junction).
a. 1st role - ________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
b. 2nd role - _______________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_____ 7. Where is Ca stored in muscle ?
A) sarcoplasmic reticulum
B) nucleus
C) Golgi apparatus
D) lysosome
8. ATP also has 2 roles in muscle contraction.
a. Describe the roles - _____________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
b. What is the condition of muscle when it is completely depleted of ATP? __________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
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9. Two proteins regulate skeletal muscle contraction.
a. Which protein blocks contraction by covering the myosin binding sites on actin?
b. Which protein does Ca bind to to trigger contraction?
10. Some skeletal muscle membranes have very short refractory periods. Why is this advantageous?
11. Heart muscle membranes have very long refractory periods. Why is this advantageous?
12. The size of the motor unit affects muscle action. What kind of motor units (large or small) is best for these
types of muscles? Explain your answers.
a. A muscle designed to give a sudden powerful contraction
b. A muscle designed to give fine graded contractions
Answer the following questions on your own paper.
13. The bacteria Clostridium botulinum grows in processed food that has not been heated to a high enough
temperature. One of the bacteria’s waste products is botulinus toxin, which can prevent the release of
neurotransmitters at neuromuscular junctions. What would happen if this were to happen to the
diaphragm muscle?
14. “Shin splints” is a painful injury that is caused from excessive pounding while running. It can be
prevented by running on soft surfaces or by adopting a running style that creates less impact. The
tendons of muscles in the lower leg pull off portions of the tibia’s periosteum, causing the pain. Make a
hypothesis about which muscles are probably causing this damage, providing an explanation for your
hypothesis.
15. Some muscles can exert forces as great as 50 pounds for each cross-sectional square inch of muscle
fiber. Measure the surface area of the cross section of your thigh. Assuming that 80% of that crosssectional area is muscle tissue, what is the maximum force that those muscles can exert?
16. The cornea of the eye acts as a lens that refracts light and creates an image on the retina. The ciliary
muscles surrounding the eye pull on small ligaments that allow the cornea to become a thicker lens. Will
light refract more, or less, as a result of the contracted ciliary muscles? Are your ciliary muscles
contracted more when you are reading the newspaper or looking at an object that is 100m away?
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