The Reflex Arc Flashcards
All 7 cards in this deck
In a reflex arc, what is the order of the three neurones involved?
Sensory neurone → relay neurone → motor neurone.
What is a synapse?
The junction (gap) between two neurones.
How is information passed across a synapse?
A chemical is released, diffuses across the gap and sets off a new electrical impulse in the next neurone.
What is meant by a 'reflex action'?
A response to a stimulus that is automatic/involuntary, with no conscious thought.
Why are reflex actions important?
They are rapid and automatic, protecting the body from danger or damage.
True or false? Reflex actions involve the conscious part of the brain.
False. The impulse does not pass through the conscious part of the brain, which is why reflexes are faster.
What are the steps of an impulse passing through a reflex arc?
e.g. touching a sharp pin
- Receptor detects stimulus, impulse passes along sensory neurone to CNS (pain receptor in finger).
- Impulse crosses a synapse to a relay neurone in the spinal cord.
- Impulse crosses another synapse to the motor neurone, which carries it to the effector (arm muscle contracts, hand pulls away).