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The Nervous System Overview

• The nervous system is broadly divided into two parts:

  • Central Nervous System (CNS): Composed of the brain and spinal cord.

  • Peripheral Nervous System (PNS): Comprises nerves that connect the CNS to the rest of the body.

Central Nervous System (CNS)

• The spinal cord is a bundle of nerves arranged in a cylindrical form with a central canal filled with cerebrospinal fluid (CSF).

• The spinal cord runs from the medulla oblongata down through the vertebral column, protected by vertebrae.

• It transmits messages between the brain and the body:

  • Carries impulses from sense organs to the CNS.

  • Conveys messages from the CNS to effector organs (muscles and glands).

Peripheral Nervous System (PNS)

• Connects the CNS to the sense organs and other body parts via nerves.

• Involved in both voluntary (somatic) and involuntary (autonomic) activities:

  • Somatic Nervous System: Controls skeletal muscle movement and processes sensory input.

  • Autonomic Nervous System: Manages involuntary functions (heartbeat, digestion) and is regulated by the medulla oblongata.

Neurons

• The basic unit of the nervous system, comprising:

  • Cyton (cell body): Contains the nucleus.

  • Dendrites: Carry impulses to the cyton.

  • Axon: Transmits impulses away from the cyton.

• Types of neurons:

  • Myelinated Neurons: Have a myelin sheath, conduct impulses faster.

  • Unmyelinated Neurons: Lack myelin sheath, conduct impulses slower.

• Synapses: Junctions where neurons connect, facilitating signal transmission.

Function of the Nervous System

• The CNS processes sensory information from the body and the environment, directing responses:

  • It sorts, analyzes, and stores information, contributing to memory and learning.

  • Directs voluntary actions through the somatic system and involuntary actions through the autonomic system.

Brain Structure

• Divided into three main parts:

  1. Cerebrum: Largest brain part responsible for higher functions:

     • Learning, memory, emotion, speech, reasoning, voluntary activities, and sensory perceptions (touch, sight, hearing, etc.).

  2. Cerebellum: Coordinates voluntary movement, balance, and posture; facilitates learning of new motor skills.

  3. Brainstem (includes medulla oblongata, pons, and midbrain): Connects brain to spinal cord; controls vital involuntary functions such as heartbeat and respiration.

Functions of Brain Parts

Summary

• The nervous system enables us to sense, react, and coordinate voluntary and involuntary actions, ensuring communication within the body and interaction with the environment.