5.3 Nerve action

Question 1

What does the soma (main cell body of the neuron) contain?

Answer 1

The usual components of any cell e.g., nucleus, DNA, mitochondria etc)

Question 2

What do the dendrons divide into?

Answer 2

Dendrites

Question 3

What do the dendrites do?

Answer 3

Pick up neurotransmitters that are being sent from other cells and send that information to the soma via an electrical signal

Question 4

Why are the dendrites long and complex?

Answer 4

Because it allows them to receive signals from many neurons at the same time

Question 5

What is the function of the axon?

Answer 5

Carry signals away from the soma to the protrusions at the end of the neuron so that messages can be sent between the neuron and an adjacent neuron.

Question 6

What is the axon coated in?

Answer 6

Myelin sheath

Question 7

What is the myelin sheath made up of?

Answer 7

Schwann cells

Question 8

What is in between each Schwann cell?

Answer 8

Tiny gaps called the nodes of Ranvier

Question 9

What is the purpose of the myelin sheath?

Answer 9

To insulate one nerve cell from another to prevent the signal from one neuron to another being interfered with.

Question 10

What is a second purpose of the myelin sheath?

Answer 10

Speed up the coordination of electrical signals travelling along the axon.

Question 11

What is the synapse?

Answer 11

A gap between two neurons

Question 12

What is a synaptic transmission?

Answer 12

The process of one neuron communicating with another neuron across the synapse

Question 13

What is the first step of the process of synaptic transmission?

Answer 13

Chemicals called transmitters are released from the axon terminal of one neuron into the synapse

Question 14

What is the second step of the process of synaptic transmission?

Answer 14

These chemical signals are picked up by receptors on the dendrites of the receiving neuron

Question 15

What is the third step of the process of synaptic transmission?

Answer 15

Depending on the type of neurotransmitter, an electrical signal will be generated, which travels away from the soma

Question 16

What is the fourth step of the process of synaptic transmission?

Answer 16

The electrical signal continues down the axon until it reaches the axon terminal

Question 17

What is the fifth step of the process of synaptic transmission?

Answer 17

This triggers the release of neurotransmitters into the synapse at the end of this neuron, which in turn can then be picked up by the dendrites of the next neuron.

Question 18

What is the structure and function of a sensory neuron?

Answer 18

Have an axon which is split into 2 parts and pick up incoming sensory signals from the peripheral nervous system and deliver these to the central nervous system.

Question 19

What is the structure and function of the motor neurones?

Answer 19

Short dendrites and long axons, and send signals from the CNS to effectors in the muscles.

Question 20

What is the structure an function of relay neurones?

Answer 20

Have short dendrites and short OR long axons, depending on their location. Communicate messages between sensory and motor neurones.