27. Which of the following describes one difference between skeletal and cardiac muscles?
Answer: A
Cardiac muscles are involuntary, whereas skeletal muscles are voluntary.
This distinction highlights that cardiac muscle operates automatically without conscious control, while skeletal muscle requires intentional effort to contract.
A) Cardiac muscles are involuntary, whereas skeletal muscles are voluntary
This option accurately captures the fundamental difference between the two muscle types. Cardiac muscles, which make up the heart, function involuntarily and are controlled by the autonomic nervous system. In contrast, skeletal muscles are under voluntary control, allowing for intentional movements of the body.
B) Skeletal muscles are not autorhythmic, whereas cardiac muscles are
This statement is partially correct but does not address the core difference in control mechanisms. While it is true that cardiac muscles are autorhythmic, the phrasing does not highlight the primary distinction of voluntary versus involuntary control that is central to understanding the functional differences between the two muscle types.
C) Skeletal muscles are found in the limbs, whereas cardiac muscles are found in the heart
Though this option correctly identifies the anatomical locations of each muscle type, it fails to discuss the functional differences related to control. Thus, while accurate, it does not address the specific difference in terms of voluntary and involuntary control.
D) Skeletal muscles are not autorhythmic
While this statement is true, it does not provide a comparison to cardiac muscles and lacks the context of involuntary versus voluntary control. This option alone does not capture the key difference being asked in the question.
Conclusion
The correct answer, A, clearly distinguishes between the involuntary nature of cardiac muscles and the voluntary nature of skeletal muscles, which is a fundamental concept in understanding muscle function. All other options either fail to address the core distinction of control mechanisms or provide information that, while accurate, is less relevant to the specific question posed.