Question

Explain how the parasympathetic division of the ANS promotes normal body functioning; give three specific examples. (p. 190)

Short answer

Answer: The primary function of the parasympathetic division is to maintain and restore the body's normal functioning and conserve energy, often referred to as the "rest-and-digest" or "feed-and-breed" activities. Three examples of specific processes regulated by the parasympathetic division are the regulation of heart rate, digestion and absorption of nutrients, and salivation and tear production.

Step-by-step solution

Introduction to the Parasympathetic Division

The parasympathetic division is a part of the autonomic nervous system (ANS), which itself is a component of the peripheral nervous system. The primary function of the parasympathetic division is to maintain and restore the body's normal functioning and conserve energy, often referred to as the "rest-and-digest" or "feed-and-breed" activities.

Physiological Processes Regulated by the Parasympathetic Division

The parasympathetic division regulates various physiological processes, such as slowing down the heart rate, increasing gastric secretion and motility, relaxing muscles, constricting the pupils, and stimulating glandular secretions. These functions work together to ensure that the body operates efficiently and conserves energy when not engaged in activities requiring a high-energy output.

Example 1: Regulation of Heart Rate

The parasympathetic division helps to regulate heart rate by releasing the neurotransmitter acetylcholine, which slows down the heart rate. This is especially important in maintaining normal bodily functions during resting periods, ensuring proper blood circulation and oxygen delivery throughout the body.

Example 2: Digestion and Absorption of Nutrients

The parasympathetic division promotes digestion and absorption of nutrients by stimulating the secretion of digestive enzymes, increasing blood flow to the gastrointestinal tract, and promoting smooth muscle contractions. This aids in breaking down food, absorbing essential nutrients, and eliminating waste, thereby maintaining overall health and body functioning.

Example 3: Salivation and Tear Production

Another function of the parasympathetic division is the stimulation of salivary and tear glands. Increased salivation keeps the mouth moist, which aids in digestion and speaking, while increased tear production keeps the eyes lubricated and clean. Both of these functions contribute to overall health and comfort in the body.