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:

• Muscles producing keratin for hair growth is not related to the peripheral nervous system maintaining internal environment. Keratin is mainly produced by epidermal cells.
• Sweat glands do not break down food. The digestive system is responsible for breaking down food.
• When it's cold, the peripheral nervous system (autonomic nervous system part) can signal muscles to contract rapidly (shivering). Shivering generates heat to help maintain body temperature (internal environment).
• The brain recalling information is related to the central nervous system (brain is part of CNS) rather than the peripheral nervous system's role in maintaining internal environment in the context of physiological homeostasis like temperature regulation.

Answer:

Muscles contract rapidly to produce heat on a cold day.