Distinguish receptors from muscle and gland effectors
Identify detection and response-producing structures in reflex examples.
Section B13.1 · Coordination and response
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Recall cell membranes, diffusion, sensitivity and the difference between cells, tissues and organs.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which is a gland effector response?
What you will learn
- Receptors detect and effectors act
- Both muscles and glands can respond
Distinguish receptors from muscle and gland effectors
A receptor detects the input. Muscles and glands are effectors, with contraction and secretion as distinct response examples. Original teaching model.
| Feature | Meaning |
|---|---|
| Receptor | Detects stimulus |
| Muscle effector | Contracts |
| Gland effector | Secretes |
| Neurones | Communicate between detection and action |
Receptors detect and effectors act
A receptor detects a stimulus, meaning a change that can be registered by the organism. An effector carries out a response. In the required nervous-system account, effectors include muscles and glands: muscle tissue can contract, while a gland can release a secretion in response to appropriate instructions.
For a supplied limb-withdrawal example, the skin receptor belongs to detection and the muscle belongs to the response-producing stage. The sensory and motor neurones between them are communicating cells. Calling the skin stimulus an effector or calling the entire contracting muscle a receptor mixes input and output roles.
Both muscles and glands can respond
A supplied gland reflex can also use a receptor input, neural communication and gland secretion as its response. A gland is not a muscle merely because both are effectors. The syllabus description therefore includes responses of both muscles and glands, rather than restricting all reflex action to visible limb movement.
Use the stated scenario to identify the actual effector and action. A drawing of a gland without information about the stimulus and pathway does not reveal every control route, and a written response should not invent a muscle contraction when the stated output is secretion. The important distinction is detection versus action, connected through the supplied neural pathway.
Sources for this lesson
Pause and explain
Which contrast is correct?
Worked example
Compare the roles of receptor and effector.
Show the worked solution
- The receptor detects the stimulus.
- The effector carries out a response such as contraction or secretion.
Answer Receptor detects; effector responds. Muscles contract and glands secrete.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State the roles of receptor and effector and give both required effector categories.
Give me a hint
Include detection, response, muscle and gland.
Compare my reasoning
- A receptor detects a stimulus.
- Muscles contract and glands secrete as effectors.
Receptor: detects stimulus. Effectors: muscles and glands carrying out responses such as contraction and secretion.
Look for these in your work
- Separate detection and response
- Name muscles and glands
A supplied reflex ends in gland secretion. Identify the effector and the response.
Give me a hint
One is a structure and the other its action.
Compare my reasoning
- The gland is the responding structure.
- Secretion is its output action.
Effector: gland. Response: secretion.
Look for these in your work
- Identify gland
- Identify secretion separately
Correct: only visible muscle movements can be reflex responses.
Give me a hint
The syllabus includes another effector category.
Compare my reasoning
- Muscles can contract.
- Glands can also respond by secretion.
Reflex responses can involve muscles or glands; gland secretion is also a response, even when no visible limb movement occurs.
Look for these in your work
- Retain muscle responses
- Include gland responses
Common mistakes
- Calling every effector a muscle.
- Treating the stimulus as a response-producing tissue.
What can you explain now?
Which contrast is correct?
Compare with the explanation
Receptor detects; effector carries out response
It separates the two end stages.
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Make it stick
Separate receptor and effector roles and name both muscle and gland responses.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.