Which of the following is true about the parasympathetic division of the autonomic nervous system?

• A. It is responsible for 'rest and digest' activities.
• B. It uses norepinephrine as its primary neurotransmitter at the effector organ.
• C. It increases heart rate and dilates pupils.
• D. Its preganglionic fibers are shorter than its postganglionic fibers.

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the parasympathetic division of the autonomic nervous system (ANS). The parasympathetic division is responsible for 'rest and digest' activities, which include conserving energy, slowing the heart rate, and promoting digestion and other metabolic processes.
2. Step 2: Recall the neurotransmitters used by the parasympathetic division. The primary neurotransmitter at the effector organ is acetylcholine (ACh), not norepinephrine. Norepinephrine is primarily used by the sympathetic division of the ANS.
3. Step 3: Analyze the physiological effects of the parasympathetic division. It generally decreases heart rate and constricts pupils, which is opposite to the sympathetic division that increases heart rate and dilates pupils during 'fight or flight' responses.
4. Step 4: Examine the structure of parasympathetic fibers. The parasympathetic division has long preganglionic fibers and short postganglionic fibers, which is the reverse of the sympathetic division.
5. Step 5: Based on the above clarifications, identify the correct statement about the parasympathetic division. The correct answer is: 'It is responsible for rest and digest activities.'