This chapter should help the student to:
- Know the three major muscle tissue types and compare their structure, function, and location.
- Know the function(s) of muscle and the measures required to sustain life without it.
- Know the relationships among muscle fascicles, muscle fibers, myofibrils, and myofilaments.
- Explain the roles of T tubules and the sarcoplasmic reticulum in striated muscle function.
- Describe muscle stimulation, contraction, and relaxation at molecular, cellular, and tissue levels.
- Recognize the type of muscle tissue present in a micrograph and describe its function(s).
1. Compare skeletal, cardiac, and smooth muscle in terms of:
Cell size and shape (Table 10–1)
Overlap of adjacent cells (IV.C)
Presence of striations (I.F; Table 10–1)
Ratio and arrangement of thick and thin filaments (II.B.1.c.; IV.B.1.c; Table 10–1)
Presence of distinct myofibrils (II.G; III.B.1; IV.B.1.c; Table 10–1)
Intracellular membrane systems (e.g., triads, dyads, caveolae) (II.B.2; III.B.1; IV.B.2; Table 10–1)
T-tubule placement (II.B.2; III.B.1; Table 10–1)
Nuclear number and position (Table 10–1)
Motor control (voluntary or involuntary; Table 10–1)
Motor end-plates (myoneural junctions; Table 10–1)
Intercalated disks (III.B.2; Table 10–1)
Capillary abundance (III.C)
2. Compare muscles, fascicles, fibers, and myofibrils of skeletal muscle (II.G; Fig. 10–2) in terms of their structural subunits and the structure that ensheathes each.
3. Sketch a longitudinal section of two resting sarcomeres attached end-to-end and label the thin filaments, thick filaments, A band, I band, Z line, H band, and M line (Fig. 10–2).
4. Which bands or lines in question 3 contain the following?
Thin filaments only (II.B.1.d)
Thick filaments only (II.B.1.d)
Both thick and thin filaments (II.B.1.d)
No actin (II.B.1.d)
No myosin (II.B.1.d)
5. Sketch the arrangement of myofilaments (Fig. 10–2) in a cross-section of a sarcomere cut through (1) the H band lateral to the M line, (2) the A band lateral to the H band, and (3) the I band.
6. Sketch a longitudinal section through two adjacent sarcomeres during contraction (II.D; Fig. 10–2). Which bands or lines shrink (compared with your drawing for question 3)?
7. How are thin filaments attached to the Z lines in skeletal muscle (II.B.1.c.) and to dense bodies in smooth muscle (IV.B.1.a)?
8. Compare thick filaments and thin filaments (II.B.1.a and b) in terms of their proteins and the names and arrangement of their subunits or components.
9. Compare troponin and tropomyosin (II.B.1.a. and ) in terms of their structure, association with thin filaments, and function during contraction.
10. Sketch a myoneural junction (motor end-plate) and label the terminal bouton, synaptic (acetylcholine) vesicles, presynaptic membrane, postsynaptic membrane, junctional folds, primary synaptic cleft, secondary synaptic clefts, and the basal lamina (Fig. 10–3).