Neurons And Synaptic Transmission

Question 1

What is a neurone?

Answer 1

A type of cell that relays messages between the CNS and the rest of the body.

Question 2

Label this diagram of a neurone:

Answer 2

Question 3

What do dendrites do?

Answer 3

Receive messages.

Question 4

What does the axon do?

Answer 4

Passes messages to other neurones, muscles or glands.

Question 5

What does the myelin sheath do?

Answer 5

Protect signals and help speed neural impulses.

Question 6

What does the axon terminal do?

Answer 6

Form junctions at other cells.

Question 7

What does the sensory neurone do?

It has ________ dendrites and ________ axons.

Answer 7

Carry nerve impulses from sensory receptors (e.g. vision, taste, touch) to the CNS.

It has long dendrites and short axons.

Question 8

What does the relay neurone do?

It has ________ dendrites and ________ axons.

Answer 8

Allows sensory neurones and motor neurones to communicate through the CNS.

It has short dendrites and short axons.

Question 9

What does the motor neurone do?

It has ________ dendrites and ________ axons.

Answer 9

Directly or indirectly controls muscles by carrying impulses from CNS to muscle glands.

It has short dendrites and long axons.

Question 10

Where are neurotransmitters located?

Answer 10

In synaptic vesicles at the axon terminals.

Question 11

What are neurotransmitters?

Answer 11

Molecules in the nervous system that transmit messages from neurones to target cells.

Question 12

What are two examples of neurotransmitters?

Answer 12

-Dopamine: pleasure & motivation.
HIGH LEVELS are linked to schizophrenia symptoms.
-Serotonin: controls emotions.
LOW LEVELS are linked to depression symptoms.

Question 13

What is synaptic transmission?

Answer 13

The process where a nerve impulse passes through the synaptic cleft (from a pre-synaptic neurone to a post-synaptic neurone).

Question 14

What is the 5 step process of synaptic transmission?

Answer 14

1. An action potential arrives at the axon terminal, waiting to pass to the next neurone.
2. When the axon potential reaches the synaptic vesicles, they release neurotransmitters to the synaptic cleft (this is exocytosis).
3. Neurotransmitters diffuse across the synaptic cleft, binding to receptor sites on the post-synaptic neurone (completing the process of synaptic transmission).
4. The neurotransmitters make it more or less likely the the post-synaptic neurone will ‘fire’.
5. Neurotransmitters that don’t bind are broken down by enzymes in the synaptic cleft OR they are reabsorbed into the pre-synaptic neurone (reuptake).

Question 15

Only ________ neurotransmitters bind to specific ________.

Answer 15

Specific, receptors.

Question 16

Label this diagram:

Answer 16

Question 17

What do excitatory neurotransmitters do?

Answer 17

They increase the likelihood that the post-synaptic neurone will ‘fire’. The electrical message is made more positive and more likely to fire (depolarisaion).

Question 18

What do inhibitory neurotransmitters do?

Answer 18

They decrease the likelihood that the post-synaptic neurone will ‘fire’. The electrical message is made more negative and less likely to fire (hyperpolarisaion).

Question 19

What is summation?

Answer 19

The net result of all excitatory and inhibitory influences on the post-synaptic neurone.

Question 20

What is an example of an excitatory neurotransmitter?

Answer 20

Noradrenaline.

Question 21

What is an example of an inhibitory neurotransmitter?

Answer 21

GABA.