While the sarcoplasmic reticulum of muscle was first described by nineteenth-century microscopists, its true significance was not ap-preciated until its intricate structure was revealed much later by the electron microscope. What could you tell a nineteenth-century microscopist to enlighten him or her about the structure of the sarcoplasmic reticulum and its role in the coupling of excitation and contraction?

Compare the rate of Ca2+ release from the sarcoplasmic reticulum to the rate of Ca2+ return back to the sarcoplasmic reticulum. Which of the following is true?  The rate of ca2+ returns is faster than the rate of ca2+ release The rate of ca2+ release is faster than the rate of ca2+ return Rates of Ca2+ release from and return to the sarcoplasmic reticulum are the same.

Do not use Ai

Draw a graph of the isometric force–length relationshipof striated muscle, indicating where maximal overlap betweenactin and myosin filaments occurs.

Distinguish between skeletal, smooth, and cardiac muscle in terms of location and whether they have sarcomeres. Use the sliding filament model to draw how thin filaments, thick filaments, and Z lines move during muscle contraction. Predict how perturbations of acetylcholine release, reception, or breakdown will influence muscle contraction. Predict how perturbations of actin, troponin, tropomyosin, myosin, or calcium would influence muscle contraction. Distinguish between the sympathetic and parasympathetic nervous system. Predict how changes in stress levels or situations would affect activation of the sympathetic and parasympathetic nervous system, levels of epinephrine and norepinephrine, and blood pressure.

Which of the following labeled zones in the electron micrograph of the sarcomere shortens during contraction? OA) B) -E C) 00) D E) -C -8

Which of the following statements is unique to skeletal muscle? O a) skeletal muscle has striations O b) skeletal muscle is attached to bones O c) skeletal muscle is under voluntary control O d) skeletal muscle is multinucleated O all of the above O b, c, & d but not a

Put these events that occur in skeletal muscle in the correct chronological sequence: 1. Opening of mechanically-gated ryanodine receptors (RyR) on the sarcoplasmic reticulum 2. Ca²+ binding to troponin to initiate contraction 3. Activation of voltage-gated dihydropyridine (DHP) receptor in the T-tubule 4. Na+ influx through ligand-gated ion channels on the motor end plate 4, 3, 2, 1 2, 1, 4, 3 3, 1, 2, 4 4, 3, 1, 2 3, 1, 4, 2

A motor unit from a skeletal muscle contains 1500 muscle fibers. Would this muscle be involved in fine, delicate movements or in powerful, gross movements? Explain.

Slow twitch muscle fibers are characterized by all of the following EXCEPT: O a) used in endurance type of activities O b) contract rapidly and forcefully Oc) resistant to fatigue O d) have a direct relationship to the oxidative energy system