Neurons (structure and function)

Question 1

What are the three types of neuron?

Answer 1

Motor neuron, sensory neuron and relay neuron.

Question 2

Outline the function of sensory neurones.

Answer 2

Carry messages from the PNS -> CNS.

Question 3

Outline the structure of sensory neurones.

Answer 3

Long dendrites, short axons.

Question 4

Outline the function of relay neurones.

Answer 4

Connect sensory neurones to motor neurones.

Question 5

Outline the structure of relay neurones.

Answer 5

Short dendrites, short axons.

Question 6

Outline the function of motor neurons.

Answer 6

Connects the CNS to effectors eg muscles.

Question 7

Outline the structure of motor neurons.

Answer 7

Short dendrites and long axons.

Question 8

What are the basic features of a neuron?

Answer 8

• cell body
• dendrites
• axon
• terminal buttons

Question 9

What is a cell body in a neurone.

Answer 9

Includes a nucleus which contains the genetic material of a cell.

Question 10

What are dendrites in a neurone.

Answer 10

Branch like structures that protrude from the cell body. These carry nerve impulses from neighbouring neurons towards the cell body.

Question 11

What is the axon in a neurone?

Answer 11

The axon carries the electrical impulse away from the cell body -> length of the neurone.

Question 12

What are the two main features of an axon in a neurone?

Answer 12

Myelin sheath and nodes of Ranvier.

Question 13

What is the importance of the myelin sheath?

Answer 13

It is a fatty layer which protects the axon.

Question 14

What is the importance of nodes of Ranvier?

Answer 14

These gals in the axon speed up the transmission of the impulse.

Question 15

What are terminal buttons in neurons?

Answer 15

These communicate with the next neuron in the chain across the synapse.

Question 16

When a neuron is in a resting state, the inside of the cell is ___________ charged compared to the outside.

Answer 16

Negatively.

Question 17

Outline how +ve and -ve charges cause an action potential to occur.

Answer 17

1. At resting state, the inside of the cell of a neuron is negatively charged.
2. When a neuron is activated, the inside of the cell becomes positively charged - causing an action potential to occur.
3. This creates an electrical impulse (which travels down the axon towards the end of the neuron).

Question 18

How are signals within neurons transmitted?

Answer 18

Electrically

Question 19

How are signals between neurons transmitted?

Answer 19

Chemically.

Question 20

Outline how synaptic transmission occurs.

Answer 20

1. The electrical impulse reaches the pre terminal, which triggers the release of neurotransmitters from synaptic vesicles.
2. Once it has crossed the synaptic cleft, it binds to receptor sites on the post neuron.
3. The chemical message is converted back -> electrical impulse.

Question 21

What are neurotransmitters?

Answer 21

Chemicals that diffuse across the synapse to the next neurone in the chain.
They generally have an excitatory or inhibitory effect.

Question 22

Give examples of neurotransmitters.

Answer 22

Acetylcholine, serotonin.

Question 23

Outline excitatory neurotransmitters.

Answer 23

Increases the +ve charge of the post neurone, making it more likely the neuron will fire.
Eg adrenaline.

Question 24

Outline inhibitory neurotransmitters.

Answer 24

Increases the -ve charge of the post neuron, making it less likely the neuron will fire.

Question 25

What is summation?

Answer 25

Excitatory and inhibitory influences are summed and mist reach a certain threshold in order for the action port with of the post neuron to be triggered.