SECTION A CLINICAL TERMS
motor end plate
muscle ﬁ ber
optimal length (L
oxidative ﬁ ber
red muscle ﬁ ber
slow ﬁ ber
slow-oxidative ﬁ ber
thick ﬁ lament
white muscle ﬁ ber
SECTION A REVIEW QUESTIONS
1. List the three types of muscle cells and their locations.
2. Diagram the arrangement of thick and thin ﬁ laments in a
striated muscle sarcomere, and label the major bands that give
rise to the striated pattern.
3. Describe the organization of myosin, actin, tropomyosin, and
troponin molecules in the thick and thin ﬁ laments.
4. Describe the four steps of one cross-bridge cycle.
5. Describe the physical state of a muscle ﬁ ber in rigor mortis and
the conditions that produce this state.
6. What three events in skeletal muscle contraction and relaxation
depend on ATP?
7. What prevents cross-bridges from attaching to sites on the thin
ﬁ laments in a resting skeletal muscle?
8. Describe the role and source of calcium ions in initiating
contraction in skeletal muscle.
9. Describe the location, structure, and function of the
sarcoplasmic reticulum in skeletal muscle ﬁ
10. Describe the structure and function of the transverse tubules.
11. Describe the events that result in the relaxation of skeletal
muscle ﬁ bers.
12. Deﬁ ne a motor unit and describe its structure.
13. Describe the sequence of events by which an action potential
in a motor neuron produces an action potential in the plasma
membrane of a skeletal muscle ﬁ
14. What is an end-plate potential, and what ions produce it?
15. Compare and contrast the transmission of electrical activity at
a neuromuscular junction with that at a synapse.
16. Describe isometric, concentric, and eccentric contractions.
17. What factors determine the duration of an isotonic twitch in
skeletal muscle? An isometric twitch?
18. What effect does increasing the frequency of action potentials
in a skeletal muscle ﬁ ber have upon the force of contraction?
Explain the mechanism responsible for this effect.
19. Describe the length-tension relationship in skeletal muscle
20. Describe the effect of increasing the load on a skeletal muscle
ﬁ ber on the velocity of shortening.
21. What is the function of creatine phosphate in skeletal muscle
22. What fuel molecules are metabolized to produce ATP during
skeletal muscle activity?
23. List the factors responsible for skeletal muscle fatigue.
24. What component of skeletal muscle ﬁ bers accounts for the
differences in the ﬁ bers’ maximal shortening velocities?
25. Summarize the characteristics of the three types of skeletal
muscle ﬁ bers.
26. Upon what three factors does the amount of tension developed
by a whole skeletal muscle depend?
27. Describe the process of motor-unit recruitment in controlling
(a) whole-muscle tension and (b) velocity of whole-muscle
28. During increases in the force of skeletal muscle contraction,
what is the order of recruitment of the different types of motor
29. What happens to skeletal muscle ﬁ bers when the motor neuron
to the muscle is destroyed?
30. Describe the changes that occur in skeletal muscles following a
period of (a) long-duration, low-intensity exercise training; and
(b) short-duration, high-intensity exercise training.
31. How are skeletal muscles arranged around joints so that a limb
can push or pull?
32. What are the advantages and disadvantages of the muscle-
bone-joint lever system?