Neurons & Synapses

Question 1

How many neurons are there in the body and where are they located?

Answer 1

100 billion
80% are located in the brain

Question 2

How are neurons transmitted ?

Answer 2

Electrically and chemically

Question 3

What does the neurons provide for the nervous system?

Answer 3

Primary means of communication

Question 4

What is the role of the sensory neuron?

Answer 4

• carry messages from PNS to CNS

Question 5

What are the features of a sensory neuron?

Answer 5

Long dendrites and short axon

Question 6

What is the role of a relay neuron?

Answer 6

• connect the sensory neuron to the motor or relay neuron.

Question 7

What are the features of a relay neuron?

Answer 7

• short dendrites and short axons

Question 8

What is the role of a motor neuron?

Answer 8

Connect the CNS to the effectors such as muscles and glands

Question 9

What are the features of motor neuron?

Answer 9

Short dendrites and long axons

Question 10

Cell body

Answer 10

Include a nucleus which contains genetic material of the cell.

Question 11

Dendrites

Answer 11

Carry nerve impulses to neighbouring neurons towards the cell body.

Question 12

Axon

Answer 12

Carry impulses away from the cell body.

Question 13

Myelin Sheath

Answer 13

The fatty layer that covers and protect the axon.

Question 14

Node of Raniver

Answer 14

Gaps in the myelin sheath to speed up electrical impulses.

Question 15

Terminal buttons

Answer 15

Communicate with next neuron in the chain across the synaptic gap.

Question 16

What is the process of neuron firing?

Answer 16

Neuron resting = postive charge outside and negative inside.When a neuron is activated by a stimulus, the inside becomes postivitely charged for a split second causing an action potential to occur.Creates an electrical impulse travels down the axon towards the end of neuron.

Question 17

What is the process of synaptic transmission?

Answer 17

• Neurons separated form the next by tiny gap (synapse).
• Signals within neurons are transmitted electrically and signals neurons are transmitted chemically across the synapse.
• when electrical impulse reaches the end of the neuron( presynaptic terminal)
• triggers the release of neurotransmitter from tiny sacs (synaptic vesicles)
  -once the neurotransmitter crosses the gap, it is taken up by the postsynaptic receptor site then it is converted back into an electrical impulse.

Question 18

What is an excitatory neuron?

Answer 18

Adrenaline- they make the next neuron more likely to fire as neuron becomes more positively charged.

Question 19

What is an inhibitory neuron?

Answer 19

Serotonin- they make they next neuron less likely to fire as neuron becomes more negatively charged.