AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
The CNS coordinates the response of effectors which may be muscles…
Full specification wording
Structure and function: The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones.
After receptors detect a stimulus, impulses travel to the central nervous system, where information is processed and a response is coordinated.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 5 of 13
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
After receptors detect a stimulus, impulses travel to the central nervous system, where information is processed and a response is coordinated. The CNS then sends impulses along motor neurones to effectors. Effectors are the parts of the body that carry out the response, and there are two main types. A muscle effector responds by contracting, which shortens the muscle and moves a body part, as when the biceps contracts to bend the arm. A gland effector responds by secreting a chemical, such as a hormone, into the blood; for example, the adrenal glands secrete adrenaline. Coordination therefore means the CNS decides which effector should respond and ensures the response is appropriate to the stimulus.
What earns the marks
- States that the CNS coordinates responses by processing information from receptors and sending impulses to effectors.
- Identifies muscles as effectors that respond by contracting.
- Identifies glands as effectors that respond by secreting hormones or other secretions.
- Links a named example to the correct effector type, such as a muscle contracting to move a limb or a gland secreting adrenaline.
- Explains that effectors bring about the response, completing the stimulus–response pathway.
Common mistakes and how to put them right
Saying muscles secrete hormones.
Put it right by stating that muscles contract and glands secrete.
Treating the CNS as the effector.
Put it right by identifying muscles or glands as the effectors that carry out the response.
Writing that glands contract.
Put it right by describing gland cells releasing a secretion such as a hormone.
Exam tips
- Name the effector type explicitly when describing a response, for example 'the muscle contracts' or 'the gland secretes a hormone'.
- Use the term effector correctly rather than writing 'the body part moves' without identifying the effector.
- Practise linking each example to the stimulus–response sequence so the role of the CNS is clear.
Try the lesson
The start of the Structure and function: The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones. lesson, made from checked teaching notes for this specification point.
Have a go first
Which two types of effector are coordinated by the central nervous system (CNS)?
Listen
After receptors detect a stimulus, impulses travel to the central nervous system, where information is processed and a response is coordinated. The CNS then sends impulses along motor neurones to effectors. Effectors are the parts of the body that carry out the response, and there are two main types. A muscle effector responds by contracting, which shortens the muscle and moves a body part, as when the biceps contracts to bend the arm. A gland effector responds by secreting a chemical, such as a hormone, into the blood; for example, the adrenal glands secrete adrenaline. Coordination therefore means the CNS decides which effector should respond and ensures the response is appropriate to the stimulus. A strong answer earns marks for these points. States that the CNS coordinates responses by processing information from receptors and sending impulses to effectors. Identifies muscles as effectors that respond by contracting. Identifies glands as effectors that respond by secreting hormones or other secretions. Links a named example to the correct effector type, such as a muscle contracting to move a limb or a gland secreting adrenaline. A common slip: Saying muscles secrete hormones. Instead, stating that muscles contract and glands secrete. Exam tip: Name the effector type explicitly when describing a response, for example 'the muscle contracts' or 'the gland secretes a hormone'.
See it
Key words
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Coordination
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Effectors
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Muscles
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Glands
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See every definition
- Coordination
- The CNS decides which effector should respond and ensures the response is appropriate to the stimulus.
- Effectors
- The parts of the body that carry out the response, of which there are two main types.
- Muscles
- Effectors that respond by contracting, which shortens the muscle and moves a body part.
- Glands
- Effectors that respond by secreting a chemical, such as a hormone, into the blood.
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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