neurons

Question 1

neuron

Answer 1

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

• 100 billion neutrons in the nervous system
• provide the nervous system with its primary means of communication

Question 2

motor neurons

Answer 2

connect CNS to effectors such as muscles and glands, have short dendrites and long axons

Question 3

relay neurons

Answer 3

connect the sensory neurons to the motor or other relay neurons, have short dendrites and short axons

Question 4

sensory neurons

Answer 4

carry messages from PNS to the CNS, have long dendrites and short axons

Question 5

structure of a neuron

Answer 5

• cell body: includes a nucleus which contains the genetic material of the cell, dendrites come out of the cell body which carry nerve impulses from neighbouring neurons towards the cell body
• axon carries the impulses away from the cell body down the length of the neuron, covered in a fatty layer (myelin sheath) that protects the axon and speeds up electrical transmission of the impulse
• nodes of ranvier: breaks up the myelin sheath to speed up the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon
• terminal buttons at the end of the exon communicate with the next neuron in the chain across the synapse

Question 6

electric transmission

Answer 6

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 causing an action potential to occur, this creates an electrical impulse that travel down the axon towards the end of the neuron