Nervous System

Main Parts

The human nervous system is broadly divided into:

1. Brain: The control center of the nervous system.
2. Spinal Cord: A long, thin, tubular bundle of nervous tissue.
3. Nerves: Bundles of nerve fibers that transmit signals throughout the body.

Brain

The brain is located inside the skull and is responsible for controlling thoughts, memory, emotions, touch, motor skills, vision, breathing, temperature, hunger, and every process that regulates our body.

• Cerebrum:
  • Location: The largest part of the brain, located in the upper front part of the skull.
  • Function: Responsible for voluntary actions, thought, memory, intelligence, language, and sensory perception (e.g., sight, hearing, touch).
• Cerebellum:
  • Location: Located at the back of the brain, below the cerebrum.
  • Function: Coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity.
• Medulla Oblongata:
  • Location: The lowest part of the brainstem, connecting the brain to the spinal cord.
  • Function: Controls vital involuntary functions such as breathing, heart rate, blood pressure, swallowing, and digestion.

Spinal Cord

• Location: Extends from the medulla oblongata down through the vertebral column.
• Function: Serves as the main pathway for information to and from the brain. It also controls reflex actions.

Types of Nerves

Nerves can be classified based on their function:

• Sensory Nerves (Afferent Nerves): Carry signals from sensory receptors to the central nervous system.
• Motor Nerves (Efferent Nerves): Transmit signals from the central nervous system to muscles and glands.
• Mixed Nerves: Contain both sensory and motor fibers, carrying signals in both directions.

Reflex Arc

A reflex arc is the neural pathway that controls a reflex, an involuntary and rapid response to a stimulus. This pathway allows for a quick reaction because the nerve impulses bypass the brain for processing, instead synapsing within the spinal cord.

Components of the Reflex Arc

• Receptor: Detects the stimulus.
• Sensory Neuron (Afferent Neuron): Transmits the nerve impulse from the receptor to the spinal cord.
• Integration Center (Interneuron): Located in the spinal cord, it connects the sensory neuron to the motor neuron.
• Motor Neuron (Efferent Neuron): Carries the nerve impulse from the integration center to the effector.
• Effector: The muscle or gland that responds to the motor neuron's signal.

[Diagram of a Reflex Arc]