AFAA Personal Trainer Certification Practice Exam

What is a distinctive feature of smooth muscle compared to skeletal muscle?

1. It is under conscious control

2. It can contract only in the presence of oxygen

3. It does not contract consciously

4. It is found primarily in the heart

The correct answer is: It does not contract consciously

Smooth muscle is characterized by its involuntary nature, meaning it does not require conscious thought for contraction. This physiological trait distinguishes it from skeletal muscle, which is under voluntary control and can be contracted consciously. Smooth muscle is typically found in the walls of hollow organs such as the intestines, blood vessels, and the bladder, facilitating essential bodily functions like digestion and blood flow without conscious effort. The other options highlight characteristics not associated with smooth muscle; for instance, its lack of conscious control is what sets it apart from skeletal muscle. Furthermore, smooth muscle does not require oxygen directly for contraction, as oxygen is utilized by all muscle types but is not a determining factor for smooth muscle activity. Similarly, the heart is primarily composed of cardiac muscle, not smooth muscle, thus reinforcing the uniqueness of smooth muscle within the broader context of muscle types in the body.