Divisions of the Nervous System

This section explores Divisions of the Nervous System as part of psychology. The nervous system is a complex network responsible for coordinating all bodily functions, from basic reflexes to complex thoughts and behaviours. It is divided into two main parts:

The Central Nervous System (CNS)

The Peripheral Nervous System (PNS), which is further divided into:

The Somatic Nervous System

The Autonomic Nervous System (with its Sympathetic and Parasympathetic branches)

Central Nervous System (CNS)

The CNS is the primary control centre for the body and consists of the brain and spinal cord.

Brain: The brain is the central hub of cognitive functions, processing sensory information and coordinating responses. It’s divided into several areas, each with specific functions (e.g., the cerebral cortex for higher-order functions like reasoning, the limbic system for emotions, etc.).

Spinal Cord: The spinal cord is a long bundle of nerves extending from the brainstem down the vertebral column. It transmits messages to and from the brain and the PNS and is responsible for some reflex actions (like the knee-jerk reflex) that do not require brain involvement.

The CNS integrates and coordinates all bodily functions by receiving sensory input, processing it, and sending out commands to muscles and glands.

Peripheral Nervous System (PNS)

The PNS connects the CNS to the limbs and organs, facilitating communication between the brain, spinal cord, and the rest of the body. It is further divided into two subsystems:

Somatic Nervous System (SNS)

The Somatic Nervous System is responsible for voluntary control of skeletal muscles and conscious sensory perception.

Sensory Neurons (Afferent Pathways): These carry information from sensory receptors (like those in the skin, muscles, and joints) to the CNS. This allows us to sense pain, temperature, touch, and other sensations.

Motor Neurons (Efferent Pathways): These transmit commands from the CNS to skeletal muscles, enabling voluntary movement.

The SNS allows for deliberate actions, such as picking up an object or moving a limb, and is critical for interacting with the environment.

Autonomic Nervous System (ANS)

The Autonomic Nervous System regulates involuntary body functions such as heartbeat, respiration, digestion, and glandular activities. It operates without conscious control and is essential for maintaining homeostasis (internal balance). The ANS is further divided into two branches:

Sympathetic Nervous System:

Often described as the “fight or flight” system, the sympathetic nervous system prepares the body for emergency or stressful situations.

When activated, it increases heart rate, dilates pupils, increases blood flow to muscles, and suppresses non-essential functions (like digestion) to maximise resources for physical activity.

Parasympathetic Nervous System:

Known as the “rest and digest” system, it is responsible for conserving energy and promoting relaxation in the body.

It slows the heart rate, reduces blood pressure, stimulates digestion, and promotes restorative functions like tissue repair.

The parasympathetic system is active during periods of calm and is critical for long-term health and recovery.

The ANS works to balance the body’s reactions to different demands, with the sympathetic and parasympathetic branches often acting in opposition to regulate bodily functions dynamically.

Summary

CNS: Composed of the brain and spinal cord; the primary control centre for processing and coordinating information.

PNS: Connects the CNS to the rest of the body and divides into:

Somatic Nervous System: Controls voluntary movements and sensory information.

Autonomic Nervous System: Regulates involuntary bodily functions with two opposing branches:

Sympathetic: Prepares the body for action.

Parasympathetic: Calms the body and conserves energy.

This division of the nervous system allows humans to respond rapidly to stimuli while maintaining essential functions, providing a balance between active engagement with the environment and physiological recovery.