Neurons

Question 1

What are neurons?

Answer 1

The basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals

Question 2

What does the cell body of a neuron do?

Answer 2

Hold the nucleus

Question 3

What does the nucleus of a neuron do?

Answer 3

Contains genetic material for each neuron (the DNA)

Question 4

What does the dendrites of a neuron do?

Answer 4

Carry electrical signals from other neurons

Question 5

What does the axon of a neuron do?

Answer 5

Carries the electrical signal away from the cell body and down the length of the neuron

Question 6

What does the myelin sheath of a neuron do?

Answer 6

It is a fatty layer that covers the axon. It is a ‘specialised’ feature of the neuron that speeds up the electrical signal

Question 7

What does the nodes of ranvier of a neuron do?

Answer 7

they are gaps in the myelin sheath that make the signal go even faster - the signal ‘jumps’ across each gap

Question 8

What does the axon terminal of a neuron do?

Answer 8

They are found at the end of the axon and are where synaptic transmission takes place

Question 9

What are the three types of neurons?

Answer 9

Sensory neurons, relay neurons and motor neurons

Question 10

What is the function of a sensory neuron?

Answer 10

Brings message from the peripheral nervous system to the central nervous system

Question 11

What is the function of a relay neuron?

Answer 11

Carry messages from one part of the CNS to another. They connect motor and sensory neurons. They also connect other relay neurons

Question 12

What is the function of a motor neuron?

Answer 12

Carry signals from the CNS to effectors in our body to execute a response, or to allow organs, glands and muscles to function

Question 13

What are the characteristics of a sensory neuron?

Answer 13

Long dendrites, short axons, a cell body within the axon

Question 14

What are the characteristics of a relay neuron?

Answer 14

Short dendrites, short axons, no myelin sheath

Question 15

What are the characteristics of a motor neuron?

Answer 15

Short dendrites, long axons, cell body at the end of the axon

Question 16

What are action potentials caused by?

Answer 16

Changes in the electrical charge in the neuron

Question 17

What happens when the action potential reaches the axon terminal?

Answer 17

It can’t go any further so it instructs chemical transmission of the message at the synapse

Question 18

Do neurons physically connect with other neurons?

Answer 18

No, there is a microscopic gap between each neuron - called the synaptic cleft

Question 19

Where does chemical transmission of a message take place?

Answer 19

At the synapse

Question 20

What is the process of chemical transmission?

Answer 20

→ When an action potential reaches the axon terminal the vesicles move and then fuse with the pre-synaptic membrane
→ This causes the neurotransmitters to be released into the synaptic cleft
→ The neurotransmitters diffuse across the synaptic cleft and attach to the receptors on the membrane of the post synaptic neuron
→ This binding then sets off an action potential in this neuron

Question 21

What are the two effects that neurotransmitters can have on the next neuron?

Answer 21

Excitatory or inhibitory

Question 22

What do excitatory neurotransmitters do?

Answer 22

Increase the neuron’s positive charge and make it more likely to fire

Question 23

What do inhibitory neurotransmitters do?

Answer 23

Increase the neuron’s negative charge and make it less likely to fire

Question 24

Give an example of an excitatory neurotransmitter

Answer 24

Adrenaline

Question 25

Give an example of an inhibitory neurotransmitter

Answer 25

Serotonin

Question 26

What happens if there are enough excitatory signals received by a neuron?

Answer 26

Summation occurs