B1: Synapses, Reflexes and The Reflex Arc

Question 1

What is a synapse?

Answer 1

The connection (gap) between two neurones.

Question 2

How is a nerve signal transferred between neurones?

Answer 2

1. There are chemicals at the end of neurone.
2. The nerve signal is transferred by these chemicals which diffuse across the synapse.
3. These chemicals set off a new electrical signal in the next neurone.

Question 3

How does a reflex prevent serious injury?

Answer 3

1. Reflexes are automatic responses to certain stimuli

2. This response reduces the chances of becoming seriously injured.

Question 4

What does the reflex arc go through?

Answer 4

The CNS.

Question 5

What happens during the reflex arc?

Answer 5

1. A stimulus is detected by the receptors and impulses are sent along a sensory neurone to the CNS.
2. The impulses reach the synapse between the sensory neurone and the relay neurone and they trigger chemicals to be released.
3. These chemicals cause impulses to be sent along the relay neurone.
4. The impulses reach a synapse between the relay neurone and the motor neurone the chemicals released cause impulses to be sent along the motor neurone.
5. The impulses travel along the motor neurone to the effector.
6. The muscle then contracts or hormones are released.

Question 6

What is the short version of the reflex arc?

Answer 6

1. Stimulus
2. Receptor
3. Sensory Neurone
4. Relay Neurone
5. Motor Neurone
6. Effector
7. Response