What is the primary function of the parasympathetic nervous system?

The primary function of the parasympathetic nervous system is indeed the relaxation and maintenance of routine activities. This division of the autonomic nervous system is responsible for promoting a state of rest and recovery in the body. It works to conserve energy and facilitate processes such as digestion, salivation, and the regulation of heart rate and blood pressure when the body is not under stress.

When activated, the parasympathetic system counters the effects of the sympathetic nervous system—often referred to as the “fight or flight” system—by slowing heart rate, increasing intestinal and gland activity, and relaxes sphincter muscles to support digestion. This is instrumental in maintaining homeostasis and ensuring that bodily functions can proceed efficiently during non-stressful conditions.

In contrast, the other choices relate to different systems or functions; for example, activating emergency responses is primarily a function of the sympathetic nervous system, while controlling voluntary movement relates more closely to the somatic nervous system. Relaying sensation information to the brain is also not a function attributed to the parasympathetic nervous system but involves pathways of sensory neurons leading to the CNS.