Nervous System - Synapses

Question 1

Synapse definition:

Answer 1

The junction between two neurones

Question 2

Name 2 examples of where synapse occurs.

Answer 2

• a sensory neurone and a relay neurone
• a relay neurone and a motor neurone

Question 3

What is the chemical that moves across the synapse

Answer 3

neurotransmitter

Question 4

Explain how the neurotransmitter travels from the sensory neurone to the relay neurone.

Answer 4

• Released from the end of the axon of the sensory neurone into the synaptic cleft
• neurotransmitter diffuses across synaptic cleft to the cell membrane of the relay neurone (dendrite)

Question 5

How does the neurotransmitter move across the synaptic cleft

Answer 5

Diffusion

Question 6

Explain how a impulse crosses the synapse (6 marks)

Answer 6

• electrical impulses sent along the neurone down to the vesicles
• causes vesicles to release neurotransmitters into synaptic cleft
• neurotransmitters diffuse across synaptic cleft
• neurotransmitters bind to the receptors on the other neurone
• electrical impulses transmitted down the other neurone

Question 7

Dendrite -

Answer 7

branched nerve fibres which receive and transmit nerve impulses to other neurones

Question 8

When an impulse arrives at the effector how will a :
a) muscle respond
b) gland respond

Answer 8

a) muscles will contract
b) glands will secrete a hormone