Problem 3 - Animal Physiology

Question

How, in general, is the vertebrate autonomic nervous system organized? Is it redundant to have separate sympathetic and parasympathetic control of many organs?

Step-by-Step Solution

Answer

The vertebrate autonomic nervous system consists of the sympathetic and parasympathetic nervous systems which work in tandem to regulate the body's responses. They have separate control of many organs to maintain balance or homeostasis in body functions. This isn't redundant, but necessary for appropriate responses to different situations.

Step 1: Understanding the Vertebrate Autonomic Nervous System

The autonomic nervous system (ANS) is part of the peripheral nervous system in vertebrates, which affects heart rate, digestion, respiration rate, salivation, perspiration, pupil dilation, and other bodily functions. It is further divided into two subsystems, the sympathetic nervous system and the parasympathetic nervous system that work in balance to regulate the body's responses to different situations.

Step 2: Describing the Sympathetic Nervous System

The Sympathetic Nervous System (SNS) is often referred to as the 'fight or flight' system. It provides the body with a burst of energy so that it can respond to perceived dangers. When activated, it prepares the body for physical activity by speeding up the heart rate, increasing blood pressure, and diverting blood flow to the muscles, heart, and brain, while slowing down processes not vital for survival in immediate danger such as digestion.

Step 3: Explaining the Parasympathetic Nervous System

The Parasympathetic Nervous System (PNS) is responsible for activities that occur when the body is at rest, also known as 'rest and digest' system. Among its functions are to slow heart rate, assist in digestion and nutrient absorption, and promote relaxation and recovery following stressful situations.

Step 4: Discussing the Need for Separate Control

Having separate sympathetic and parasympathetic control of many organs is not redundant. These systems often work in opposite ways to maintain homeostasis in the body. For example, where the SNS accelerates heart rate, the PNS slows it down. It's this balance between the two systems that allows the body to respond appropriately to changing conditions.