The Nervous System (Cambridge (CIE) A Level Biology): Revision Note
The Nervous System
The human nervous system consists of the following:
Central nervous system (CNS) – the brain and the spinal cord
Peripheral nervous system (PNS) – all of the nerves in the body
It allows us to make sense of our surroundings and respond to them and to coordinate and regulate body functions
Information is sent through the nervous system as nerve impulses – electrical signals that pass along nerve cells known as neurones
A bundle of neurones is known as a nerve
Neurones coordinate the activities of sensory receptors (eg. those in the eye), decision-making centres in the central nervous system, and effectors such as muscles and glands
The nervous system diagram
The human nervous system comprises the central and peripheral nervous systems
Comparing the nervous and endocrine systems table
Feature | Nervous system | Endocrine system |
|---|---|---|
Parts of the system | Brains, spinal cord, nerves/neurones | Glands |
Type of message | Electrical impulse | (Chemical) hormone |
Method of transmission | Neurones | Bloodstream |
Effectors | Muscles of glands | Target cells in specific tissues |
Speed of transmission | Very fast | Slower |
Duration of effect | Short - until electrical impulses stop | Longer - until the hormone is broken down |
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