The structure and function of a reflex arc
I can describe what a reflex response is and the path a nerve impulse takes through a reflex arc in the nervous system.
The structure and function of a reflex arc
I can describe what a reflex response is and the path a nerve impulse takes through a reflex arc in the nervous system.
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Lesson details
Key learning points
- Reflex responses are fast and involuntary, and are essential to the survival of many organisms.
- Reflex responses do not involve a processing centre (e.g. the brain) in the CNS.
- In a reflex arc, the nerve impulse travels across a synapse from the sensory neurone to a relay neurone in the CNS.
- The nerve impulse travels across a synapse from the relay neurone to a motor neurone in the PNS.
- Sometimes the brain can modify (e.g. stop) a reflex response via a neurone to the motor neurone of the reflex arc.
Keywords
Involuntary - Something that occurs without you realising or controlling it.
Reflex response - An involuntary, fast neural response to a situation.
Reflex arc - The fixed neural pathway that controls the reflex response.
Relay neurone - An intermediate neurone that sits within the central nervous system.
Common misconception
What constitutes a reflex response, and how they are generated in the body is often confused and muddled, leading to an incorrect mix between a standard neural pathway and the reflex pathway.
The reflex pathway is clearly stated and explained, and it is compared to the standard neural pathway. Plenty of examples of reflexes are given, including those that occur in other organisms, and there is a quick practical to try too.
Equipment
None required.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What makes up the central nervous system?
Q2.What does involuntary mean?
Q3.Which of the following is not a feature of nerve cells?
Q4.Muscles and glands are known as ...
Q5.Put these steps in order to show how a nervous impulse travels to the brain.
Q6.Put these steps in order to show how a synapse works.
Assessment exit quiz
6 Questions
Q1.What could cause a reflex reaction?
Q2.What three types of neurone are involved in a reflex arc?
