In human physiology, what does the autonomic nervous system (ANS) primarily control?

• A. Conscious perception of touch, pain, and temperature from the skin
• B. Regulation of blood cell production in red bone marrow
• C. Voluntary movement of skeletal muscles
• D. Involuntary functions of smooth muscle, cardiac muscle, and glands (e.g., heart rate, digestion, sweating)

Answer: (D)

Verified step by step guidance

1. Understand that the autonomic nervous system (ANS) is a part of the peripheral nervous system responsible for regulating involuntary body functions.
2. Recognize that the ANS primarily controls activities that are not consciously directed, such as the function of smooth muscle, cardiac muscle, and glands.
3. Differentiate the ANS from the somatic nervous system, which controls voluntary movements like skeletal muscle contractions and conscious sensory perception.
4. Identify examples of ANS-controlled functions, including heart rate regulation, digestion, and sweating, which occur without conscious effort.
5. Conclude that the ANS does not control conscious sensations (like touch or pain) or voluntary muscle movements, but instead manages involuntary physiological processes essential for homeostasis.