The Structure and Function of Neurons

Question 1

Neuron - cell body

Answer 1

Contains nucleus, which contains all genetic material of the cell

Question 2

Neuron - dendrites

Answer 2

Branch like structures that project from the cell body. Carry impulses from other neurons towards the cell body.

Question 3

Neuron - axons

Answer 3

Carry impulses away from the cell body down the length of the neuron

Question 4

Neuron - myelin sheath

Answer 4

A layer that covers the axon and speeds up the electrical impulse

Question 5

Neuron - Nodes of Ranvier

Answer 5

Segments the myelin sheath. They speed up transmission of the impulse by forcing it to ‘jump’ across gaps along the axon

Question 6

Neuron - terminal buttons

Answer 6

At the end of the axon and communicate with the next neuron in the chain across the synaptic gap by using neurotransmitters

Question 7

What is a sensory neuron?

Answer 7

Found in receptors and carry nerve impulses to the spinal cord and brain. When the impulses reach the brain, they are translated into sensations such as vision, hearing, taste or touch to give information about the environment. Some neurons stop at the spinal cord, allowing for quick research actions.

Question 8

What is the structure of the sensory neuron?

Answer 8

Long dendrites and short axons

Question 9

What is a relay neuron?

Answer 9

Found in the brain and spinal cord, and allow sensory and motor neurons to communicate. They are found between sensory input and motor output.

Question 10

What is the structure of a relay neuron?

Answer 10

Short dendrites, and long or short axons

Question 11

What is a motor neuron?

Answer 11

Found in the CNS and control muscle movement. When they are stimulated, they release neurotransmitters that bind to the receptors on the muscles to trigger a response.

Question 12

What is the structure of a motor neuron?

Answer 12

Short dendrites and long axons

Question 13

What is the first stage of synaptic transmission?

Answer 13

Dendrite picks up NTs and sends an action potential through the cell body and along the axon to the terminal button.

Question 14

What is the second stage of synaptic transmission?

Answer 14

Once the action potential has reached the terminal button, it needs to be transferred to another neuron. To achieve this it must cross the synaptic gap between pre and post synaptic neuron.

Question 15

What is the third stage of synaptic transmission?

Answer 15

Synaptic vesicles store NTs - chemical messengers that convert the impulse to a chemical message

Question 16

What is the fourth stage of synaptic transmission?

Answer 16

As the impulse reaches the synaptic vesicle, they release the NTs that cross the synaptic gap

Question 17

What is the fifth stage of synaptic transmission?

Answer 17

The NT diffuses across the synaptic gap then binds to the specialist receptors on the surface of the next cell that recognise it and match that particular cell - eg dopamine receptors recognise dopamine

Question 18

What is the sixth stage of synaptic transmission?

Answer 18

Once the next cell is activated the receptor molecules produce either an excitatory effect or an inhibitory effect depending on the summation of activity at a post synaptic level.

Question 19

What is the seventh stage of synaptic transmission?

Answer 19

It is completed by a process called reuptake. This is where the NT is taken back up/recycled by the pre-synaptic neuron

Question 20

What are the key areas of synaptic transmission?

Answer 20

Synaptic vesicle
Terminal button
Synaptic gap
Receptor
Neurotransmitters
Post synaptic neuron

Question 21

What is a neurotransmitter?

Answer 21

Chemicals that are released from the end of brain cells that allow them to communicate with each other and relay messages to different areas of the brain. As one neuron releases an NT, receptors on other neurons pick up this message and relay it to the next neuron. Neurotransmitters affect the transfer of an impulse to another neuron or muscle.

Question 22

What is an excitatory effect?

Answer 22

They create a positive charge, making the neuron more likely to fire. This rise in action potential will increase activity.

Question 23

What is an inhibitory effect?

Answer 23

They create a negative charge, making the neuron less likely to fire. This fall in action potential will decrease activity.