1. Each muscle fiber is a bundle of myofibrils. Eachmyofibril is a series of sarcomeres. Thus, a muscle fiber contractswhen each sarcomere within a series contracts simultaneously. Suchcoincidence is mirrored by each myobril within the muscle fiber.What enables the extent to which molecular motors contractsimultaneously within an innervated muscle fiber?
a. the frequency of acetylcholine secretion within theneuromuscular synapse
b. the frequency of Ca2+ oscillations within themuscle fiber
2. A living muscle fiber experiences dynamic frequencies ofCa2+ oscillations. In effect, Ca2+ acts as asecond messenger when it disperses throughout the fluid-filledspaces between actin and myosin filaments. What is the source ofthis second message?
a. extracellular fluid b.sarcoplasmic reticulum
3. Why might a muscle fiber need an ample amount ofNa+,K+-ATPase on itssurface?
a. as evident by the value of the cellâs membrane potential,muscle fibers are leaky to Na+
b. to counter the effect of numerous action potentials persecond
4. Assume that you could âseeâ nicotinic acetylcholine receptorswithin the musculature. How would they be arranged spatially?
a. evenly distributed on the cellâs surface like voltage-gatedNa+ and K+ channels
b. in dense arrays within the motor end plate
5. Assume that you could âseeâ neurosecretion fromα-motor neurons within the musculature of an animal standing still.What would this âlookâ like?
a. uniform, baseline secretion throughout the musculature
b. enhanced acetylcholine secretion within antigravity muscles,baseline secretion elsewhere
1. Each muscle fiber is a bundle of myofibrils. Eachmyofibril is a series of sarcomeres. Thus, a muscle fiber contractswhen each sarcomere within a series contracts simultaneously. Suchcoincidence is mirrored by each myobril within the muscle fiber.What enables the extent to which molecular motors contractsimultaneously within an innervated muscle fiber?
a. the frequency of acetylcholine secretion within theneuromuscular synapse
b. the frequency of Ca2+ oscillations within themuscle fiber
2. A living muscle fiber experiences dynamic frequencies ofCa2+ oscillations. In effect, Ca2+ acts as asecond messenger when it disperses throughout the fluid-filledspaces between actin and myosin filaments. What is the source ofthis second message?
a. extracellular fluid b.sarcoplasmic reticulum
3. Why might a muscle fiber need an ample amount ofNa+,K+-ATPase on itssurface?
a. as evident by the value of the cellâs membrane potential,muscle fibers are leaky to Na+
b. to counter the effect of numerous action potentials persecond
4. Assume that you could âseeâ nicotinic acetylcholine receptorswithin the musculature. How would they be arranged spatially?
a. evenly distributed on the cellâs surface like voltage-gatedNa+ and K+ channels
b. in dense arrays within the motor end plate
5. Assume that you could âseeâ neurosecretion fromα-motor neurons within the musculature of an animal standing still.What would this âlookâ like?
a. uniform, baseline secretion throughout the musculature
b. enhanced acetylcholine secretion within antigravity muscles,baseline secretion elsewhere
