Topic 5a- Reflexes and reaction times

Question 1

Explain the reflex arc

Answer 1

1. A stimulus is detected by a receptor.
2. Electrical impulses are sent down a sensory neurone to a relay neurone in the central nervous system.
3. The electrical impulse reaches a synapse between the sensory and relay neurones, chemicals then diffuse across the synapse allowing the electrical impulse to continue down the relay neurone.
4. This reoccurs when the impulse travels across the synapse between the relay neurone and the motor neurone. Chemicals are released and cause electrical impulses to be sent along the motor neurone.
5. The impulses then travel along the motor neurone to the effector (usually a muscle)
6. If the effector is a muscle, it will contract. If the effector is a gland, it will secrete a hormone.

Question 2

What are reflexes?

Answer 2

Fast, automatic responses that bypass your conscious brain when a quick response is essential.

Question 3

What is a reaction time?

Answer 3

Reaction time is the amount of time it takes someone to respond to a stimulus.