neurons

Question 1

what are neurons?

Answer 1

nerve cells that process and transmit messages through electrical and chemical signals

Question 2

what are the 3 types of neurons?

Answer 2

1. sensory neurons
2. relay neurons
3. motor neurons

Question 3

what is the role of sensory neurons?

Answer 3

carry messages from PNS to CNS

Question 4

what is the role of relay neurons?

Answer 4

connect sensory neuron to motor or other relay neurons

Question 5

what is the role of motor neurons?

Answer 5

connect CNS to effectors (eg. muscles, glands)

Question 6

what is the length of the dendrites and axons of the 3 neurons?

Answer 6

• sensory - long dendrites, short axons
• relay - short dendrites, short axons
• motor - short dendrites, long axons

Question 7

what is the soma in a neuron?

Answer 7

• cell body
• includes a nucleus which contains genetic material of cell

Question 8

what do dendrites do?

Answer 8

carry nerve impulses from neighbouring neurons towards the cell body

Question 9

what does the axon do?

Answer 9

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

Question 10

what is the myelin sheath

Answer 10

fatty later that covers and protects the axon

Question 11

what is the purpose of the myelin sheath?

Answer 11

speeds up electrical transmission of the impulse

Question 12

what are the nodes of ranvier?

Answer 12

gaps in the myelin sheath

Question 13

what is the purpose of the nodes of ranvier?

Answer 13

speed up the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon

Question 14

what are terminal buttons?

Answer 14

• at the end of the axon
• communicate with the next neuron in the chain across a synapse

Question 15

where are motor neurons found?

Answer 15

• cell bodies in the CNS
• have long axons so form part of PNS

Question 16

where are sensory neurons found?

Answer 16

• outside of CNS
• in PNS in clusters known as ganglia

Question 17

where are relay neurons found?

Answer 17

• make up 97% of all neurons
• most are found in brain and visual system

Question 18

how is an electrical impulse that travels down the axon towards the end of the neuron created?

Answer 18

• when a neuron is in a resting state, the inside of the cell is negatively charged compared to the outside
• when a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second
• this causes action potential to occur