Nervous System Organisation

Nervous System Organisation

Central Nervous System (CNS)

• Composed of the brain and the spinal cord.
• Acts as the body’s primary control centre.
• Processes and interprets information obtained through the peripheral nervous system.

Peripheral Nervous System (PNS)

• Includes all nerves outside of the CNS.
• Connects the CNS to the rest of the body.
• Subdivided into the somatic and autonomic nervous systems.

The Somatic Nervous System

• Controls voluntary movements.
• Is responsible for reflex arcs.

The Autonomic Nervous System

• Controls involuntary bodily functions such as heart rate and digestion.
• Divided into the sympathetic and parasympathetic nervous systems.

Sympathetic Nervous System

• Activates the body’s ‘fight or flight’ response.
• Increases heart rate, dilates pupils, and inhibits digestion.

Parasympathetic Nervous System

• Activates the body’s ‘rest and digest’ response.
• Decreases heart rate, constricts pupils, and stimulates digestion.

Neurons and their Function

• Neurons (nerve cells) carry messages as electrical impulses around the body.

Motor Neurons

• Carry messages from the CNS to effectors (muscles and glands).

Sensory Neurons

• Carry messages from sensory receptors to the CNS.

Interneurons (Relay Neurons)

• Connect sensory and motor neurons and interpret the impulse.

The Brain

• Is divided into several regions each having a unique function.
• These include the cerebrum (thinking, personality), the cerebellum (movement, balance), and the medulla (unconscious activities).

The Spinal Cord

• Is a long, thin, tubular structure that connects to the brain.
• Responsible for reflex actions and transmitting neural signals between the brain and the rest of the body.

Remember the most important feature of the nervous system is its organisation and its ability to communicate and coordinate different parts of the body by transmitting signals.