Muscle tension is sensed by ________, whereas muscle fiber length is sensed by ________.
a. extrafusal fibers; Golgi tendon organs
b. intrafusal fibers; extrafusal fibers
c. Golgi tendon organs; intrafusal fibers
d. motor neurons; intrafusal fibers
e. multiunit fibers; myofibrils
Question 2
The physical effects of a muscle twitch last longer than the action potential that triggered the contraction because
a. muscle fibers lack elasticity.
b. it takes time to extrude calcium ions out of the fiber.
c. the acetylcholine molecules are slowly cleared from the neuromuscular junction.
d. the twitches run back and forth along the muscle fiber.
e. muscle fibers are thicker than axons.
