Question

which is an example of how the peripheral nervous system helps the body maintain its internal environment?
○ muscles produce keratin so that hair can grow stronger.
○ sweat glands break down the food that is consumed.
○ muscles contract rapidly to produce heat on a cold day.
○ the brain recalls information to help take a test.

Explanation:

1. Analyze Option 1: Keratin production is by epithelial cells (like those in hair follicles), not muscles, so this is incorrect.
2. Analyze Option 2: Sweat glands are for sweating (thermoregulation, excretion), not digestion. Digestion is by digestive organs, so this is incorrect.
3. Analyze Option 3: The peripheral nervous system controls muscle contractions. On a cold day, muscles contracting rapidly (shivering) produces heat, helping maintain body temperature (internal environment), so this is correct.
4. Analyze Option 4: The brain (central nervous system) recalling information is a central nervous system function, not peripheral, so this is incorrect.

Answer:

Muscles contract rapidly to produce heat on a cold day.