Question

Which part of the nervous system directly controls the digestive system? a. parasympathetic nervous system b. central nervous system c. spinal cord d. sensory-somatic nervous system

Short answer

Answer: (a) Parasympathetic nervous system

Step-by-step solution

Understand the nervous system components and their functions

The nervous system has two main divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord and is responsible for processing information gathered by the PNS. The PNS, on the other hand, connects the CNS to the rest of the body and is divided further into the somatic (voluntary) and autonomic (involuntary) systems. The autonomic nervous system can be subdivided into the sympathetic and parasympathetic divisions, which coordinate involuntary responses to maintain body homeostasis.

Identify the part responsible for controlling the digestive system

Given that the digestive system functions are involuntary, we can rule out options (c) spinal cord and (d) sensory-somatic nervous system. The central nervous system (option b) plays a role in processing signals but does not directly control the digestive system. Therefore, the remaining option (a) parasympathetic nervous system is the part of the nervous system that directly controls the digestive system. The parasympathetic nervous system coordinates the "rest and digest" functions, such as stimulating saliva production, increasing digestive enzyme secretion, and promoting gut motility.

Select the answer

Based on the analysis, the correct answer is (a) parasympathetic nervous system, as it is the part of the nervous system that directly controls the digestive system.

Key concepts

Parasympathetic Nervous System

The parasympathetic nervous system (PNS) plays a crucial role in managing our body's rest and digest activities. It is part of the larger autonomic nervous system which operates largely outside of our conscious control, regulating functions like heart rate, digestion, and respiratory rate.

When it comes to digestion, the PNS is like a calm conductor of an orchestra, activating processes that help our body conserve energy and process food. For instance, it stimulates saliva production to aid in digestion and enhances the secretion of digestive enzymes which break down the food we consume. It also encourages the muscles in our gastrointestinal tract to contract, which moves food through the stomach and intestines more effectively.

The PNS's counterpart, the sympathetic nervous system, initiates the 'fight or flight' response. During such responses, digestion is not the priority, and thus its activities are often suppressed. This delicately balanced interplay between the two systems allows our body to adapt to both restful and stressful situations efficiently.

Autonomic Nervous System

The autonomic nervous system (ANS) may not be as well-known as the central nervous system, but it's no less important. It comprises two divisions: the sympathetic nervous system and the parasympathetic nervous system, mentioned earlier. Together, they maintain the balance of our body's involuntary functions.

The key to understanding the ANS is realizing its role in homeostasis - the stability and balance of your internal environment. It makes adjustments on the fly without you even noticing, keeping your heart beating, your body temperature regulated, and your digestive system churning away, all without conscious thought.

When you're faced with danger, the sympathetic division prepares your body to respond, while, in contrast, the parasympathetic division calms your body down once the danger passes. It's this constant balancing act that keeps us alive and functioning.

Central Nervous System

The central nervous system (CNS) is often heralded as the command center of our body. It consists of the brain and spinal cord and is responsible for interpreting sensory information and coordinating bodily responses.

Think of it as the brain of operations, where the sensory data collected from the eyes, ears, and other organs is turned into perception, memories, and thoughts. The CNS is also where decisions are made, from the blink of an eye to the planning of complex movements.

Despite its indirect role in controlling the digestive system, the CNS is critical for processing the information that influences the autonomic nervous system's activity. For example, the sight and smell of food can trigger the CNS to activate the parasympathetic nervous system, preparing the gut for incoming food.

Peripheral Nervous System

The peripheral nervous system (PNS) is like the body's messaging system, linking the central nervous system to the rest of your body. Unlike the CNS, which is contained within the brain and spinal cord, the PNS spreads out and contains all the nerves that branch out to other parts of the body.

The PNS's primary function is communication. It carries signals from the brain to the muscles to enable movement, and it also sends information from the sensory receptors back to the brain. The PNS is divided into the somatic nervous system, which controls voluntary movements, and the autonomic nervous system, responsible for involuntary functions.

Through the PNS, the CNS can send instructions to the rest of the body and receive feedback on what's happening in the external environment, allowing the body to adapt and react effectively.