AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Structure and function: The CNS is the brain and spinal cord.
The central nervous system, or CNS, is the body's main processing centre and consists of two linked organs: the brain and the spinal cord.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 4 of 13
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The central nervous system, or CNS, is the body's main processing centre and consists of two linked organs: the brain and the spinal cord. The brain receives information from receptors, integrates it and issues instructions; the spinal cord carries signals between the brain and the rest of the body and also coordinates some rapid reflexes on its own. In mammals the CNS is protected by the skull and vertebral column, and by membranes and fluid. It is distinct from the peripheral nervous system, which is the network of nerves connecting receptors and effectors to the CNS.
For example: Touching a hot object sends impulses along sensory neurones into the spinal cord, which can trigger a response even before the brain consciously registers pain.
What earns the marks
- States that the CNS comprises the brain and the spinal cord, naming both organs.
- Describes the brain as a processing centre that receives information and coordinates responses.
- Describes the spinal cord as a link carrying impulses between the brain and the body, and as a centre for some reflex actions.
- Distinguishes the CNS from the peripheral nervous system, which consists of nerves connecting receptors and effectors to the CNS.
- Relates CNS structure to protection, for example the skull around the brain and vertebrae around the spinal cord.
Common mistakes and how to put them right
Thinking the CNS includes all nerves in the body.
Put it right by stating that peripheral nerves are outside the CNS and only the brain and spinal cord form it.
Believing the spinal cord is only a cable and never processes information.
Put it right by noting that it coordinates some reflex responses.
Confusing the CNS with the brain alone.
Put it right by naming both the brain and the spinal cord.
Exam tips
- Use the exact term central nervous system and its abbreviation CNS at least once in a response.
- When asked to identify parts of the CNS, label the brain and spinal cord rather than naming individual nerves.
- Link the CNS to a named example, such as a reflex triggered by touching a hot surface, to show understanding rather than recall alone.
Try the lesson
The start of the Structure and function: The CNS is the brain and spinal cord. lesson, made from checked teaching notes for this specification point.
Have a go first
Which two organs make up the central nervous system (CNS) in humans?
Listen
The central nervous system, or CNS, is the body's main processing centre and consists of two linked organs: the brain and the spinal cord. The brain receives information from receptors, integrates it and issues instructions; the spinal cord carries signals between the brain and the rest of the body and also coordinates some rapid reflexes on its own. In mammals the CNS is protected by the skull and vertebral column, and by membranes and fluid. It is distinct from the peripheral nervous system, which is the network of nerves connecting receptors and effectors to the CNS. For example, touching a hot object sends impulses along sensory neurones into the spinal cord, which can trigger a response even before the brain consciously registers pain. A strong answer earns marks for these points. States that the CNS comprises the brain and the spinal cord, naming both organs. Describes the brain as a processing centre that receives information and coordinates responses. Describes the spinal cord as a link carrying impulses between the brain and the body, and as a centre for some reflex actions. Distinguishes the CNS from the peripheral nervous system, which consists of nerves connecting receptors and effectors to the CNS. A common slip: Thinking the CNS includes all nerves in the body. Instead, stating that peripheral nerves are outside the CNS and only the brain and spinal cord form it. Exam tip: Use the exact term central nervous system and its abbreviation CNS at least once in a response.
See it
Key words
Say what each word means before you turn the card.
Central nervous system
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Brain
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Spinal cord
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Peripheral nervous system
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See every definition
- Central nervous system
- The body's main processing centre, consisting of two linked organs: the brain and the spinal cord.
- Brain
- A processing centre that receives information from receptors, integrates it and issues instructions.
- Spinal cord
- Carries signals between the brain and the rest of the body and also coordinates some rapid reflexes on its own.
- Peripheral nervous system
- The network of nerves connecting receptors and effectors to the CNS.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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