Anatomy & Physiology Nervous #2


Which is a function of the parasympathetic nervous system (PNS)?


  1. Dilating the pupils
    • Rationale:

      The PNS does not cause pupil dilation; therefore, this is not a function of this branch of the ANS. Stimulation of the sympathetic nervous system (SNS) causes the pupils to dilate.

  2. Enhancing digestion
    • Rationale:

      The PNS increases the rate of digestion; therefore, enhancing digestion is a noted function of this system.

  3. Decreasing respirations
    • Rationale:

      Respirations are not impacted by the PNS. The respiratory rate is increased with SNS stimulation.

  4. Increasing the heart rate
    • Rationale:

      The PNS lowers the heart rate. It is the ANS, not the PNS, that increases the heart rate.


The parasympathetic nervous system (PNS) is a division of the autonomic nervous system (ANS).


Learning Outcomes

The PNS is often referred to as the digest and rest system. It allows the body to conserve energy. The PNS accomplishes this task by slowing the heart rate, increasing intestinal (i.e., enhancing digestion) and gland activity, and by relaxing the sphincter muscles of the gastrointestinal (GI) tract.

Test Taking Tip

Consider the function of the parasympathetic nervous system (PNS) to eliminate wrong choices when answering this question.

Video Rationale