Overview of the Nervous System

Overview of the Nervous System

Introduction

The nervous system is a complex network that coordinates actions and transmits signals between different parts of the body. It is essential for processing sensory information, controlling bodily functions, and enabling cognition and behavior. This section provides an overview of the major subdivisions of the human nervous system and their functions.

Main Divisions of the Nervous System

Central Nervous System (CNS)

The Central Nervous System consists of the brain and spinal cord. It is housed within the skull and vertebral column and serves as the primary decision maker for the body.

• Brain: Responsible for higher-order functions such as thought, memory, emotion, and voluntary movement.

• Spinal Cord: Acts as a conduit for signals between the brain and the rest of the body; also coordinates reflexes.

Peripheral Nervous System (PNS)

The Peripheral Nervous System includes all nerves outside the brain and spinal cord. It connects the CNS to limbs and organs and is divided into two main categories: the somatic and autonomic nervous systems.

• Somatic Nervous System: Governs voluntary movements by controlling skeletal muscles.

• Autonomic Nervous System: Regulates involuntary bodily functions such as heart rate, digestion, and respiratory rate.

Subdivisions of the Autonomic Nervous System

Sympathetic Nervous System

The Sympathetic Nervous System is responsible for the "fight-or-flight" response, preparing the body for action in stressful situations.

• Increases heart rate and blood pressure

• Redirects blood flow to muscles

• Inhibits digestion

Parasympathetic Nervous System

The Parasympathetic Nervous System promotes "rest and digest" functions, conserving energy and maintaining routine bodily functions.

• Decreases heart rate

• Stimulates digestion

• Promotes relaxation

Somatic Nervous System

The Somatic Nervous System enables voluntary control of skeletal muscles and is involved in conscious movement.

• Controls activities such as walking, writing, and speaking

• Processes sensory input from the environment

Neural Pathways and Reflexes

Reflex Arc

A reflex arc is the neural pathway that mediates a reflex action. Reflexes are rapid, involuntary responses to stimuli, often bypassing the brain for faster reaction times.

• Sensory Neurons (Afferent): Carry information from sensory receptors to the CNS.

• Motor Neurons (Efferent): Transmit commands from the CNS to muscles and glands.

Example: The knee-jerk reflex is a classic example of a simple reflex arc.

Summary Table: Divisions and Functions of the Nervous System

Division	Main Components	Primary Function
Central Nervous System (CNS)	Brain, Spinal Cord	Processing information, decision making
Peripheral Nervous System (PNS)	Nerves outside CNS	Connects CNS to limbs and organs
Somatic Nervous System	Sensory and motor nerves	Voluntary movement
Autonomic Nervous System	Sympathetic & Parasympathetic divisions	Involuntary functions
Sympathetic Nervous System	Part of Autonomic NS	"Fight-or-flight" response
Parasympathetic Nervous System	Part of Autonomic NS	"Rest and digest" response

Key Terms and Definitions

• Neuron: A nerve cell that transmits electrical and chemical signals in the nervous system.

• Afferent (Sensory) Neurons: Carry information from sensory receptors to the CNS.

• Efferent (Motor) Neurons: Carry commands from the CNS to muscles and glands.

• Reflex: An automatic, rapid response to a stimulus.

Suggested Skills

• Apply psychological perspectives, theories, concepts, and research findings to scenarios.

• Identify psychology-related concepts in discussions or representations of data.

Additional info: The notes have been expanded to include definitions, examples, and a summary table for clarity and completeness.