Which of the following statements regarding skeletal muscle is NOT true?
A Skeletal muscle is responsible for overall body motility.
B Skeletal muscle can contract rapidly and can maintain the contraction for long periods of activity
C Skeletal muscle can exert tremendous power.
D Skeletal muscle is called voluntary muscle because it is the only type subject to conscious control.
The correct answer and explanation is :
The correct answer is B: Skeletal muscle can contract rapidly and can maintain the contraction for long periods of activity.
Explanation:
A: Skeletal muscle is responsible for overall body motility.
This statement is true. Skeletal muscles are attached to bones and are primarily responsible for moving the body and limbs. These muscles generate the force needed for voluntary movements, such as walking, running, and lifting.
B: Skeletal muscle can contract rapidly and can maintain the contraction for long periods of activity.
This statement is NOT true. While skeletal muscles can contract rapidly, they cannot maintain sustained contractions for long periods without fatigue. Skeletal muscles rely on the availability of energy sources (e.g., ATP), and after prolonged use, they become fatigued due to the depletion of these energy sources. This is in contrast to smooth muscle or cardiac muscle, which can maintain prolonged activity. For example, smooth muscle in the digestive tract or cardiac muscle in the heart can sustain contractions for long periods without tiring.
C: Skeletal muscle can exert tremendous power.
This statement is true. Skeletal muscles are capable of generating significant force, especially in larger muscles like the quadriceps, hamstrings, and biceps. These muscles can exert a large amount of power in activities like lifting heavy weights, sprinting, and jumping.
D: Skeletal muscle is called voluntary muscle because it is the only type subject to conscious control.
This statement is true. Skeletal muscle is considered voluntary muscle because it is controlled consciously by the somatic nervous system. This contrasts with involuntary muscles, such as smooth muscle and cardiac muscle, which function automatically without conscious control.
In summary, skeletal muscles can contract rapidly and exert substantial force but are unable to maintain contraction over long periods without fatigue, making statement B the correct answer.