The Nervous System: Neurones and Impulse Transmission

This lesson covers the structure and function of neurones and the mechanism of nerve impulse transmission as required by the Edexcel A-Level Biology specification (9BI0), Topic 9 -- Control Systems. You need to understand the types of neurones, the resting potential, and the action potential in detail.

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Organisation of the Nervous System

The nervous system is divided into two main parts:

Division	Components	Function
Central Nervous System (CNS)	Brain and spinal cord	Processing and integration of information
Peripheral Nervous System (PNS)	Sensory and motor neurones	Carries impulses to and from the CNS

The PNS is further divided into:

• Somatic nervous system -- controls voluntary actions (skeletal muscles)
• Autonomic nervous system -- controls involuntary actions (smooth muscle, cardiac muscle, glands)

The autonomic nervous system has two branches:

• Sympathetic -- prepares the body for action ('fight or flight')
• Parasympathetic -- promotes 'rest and digest' activities

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Types of Neurones

There are three main types of neurone: