structure and role of neuron

Question 1

cell body

Answer 1

includes a nucleus containing the genetic material of the cell

Question 2

dendrites

Answer 2

branch-like structures sticking out of the cell body, carry impulses from other neurons to the cell body

Question 3

axon

Answer 3

a tube like structure, carries the impulses away from the cell body down the length of the neuron

Question 4

myelin sheath

Answer 4

in many neurones, the axon is covered by a fatty layer formed from special cells
this protects the axon and speeds up transmission of the impulse

Question 5

nodes of Ranvier

Answer 5

gaps in the myelin sheath increase speed by forcing the impulses to ‘jump’ across the gaps along the length of the axon

Question 6

terminal buttons

Answer 6

at the end of axons, not physically connected to the next neuron, but involved in communication across a synapse

Question 7

sensory neurons

Answer 7

carry messages from sensory receptors (e.g., touch and temperature sensitive receptors in the skin) along nerves in the PNS to the CNS

Question 8

motor neurons

Answer 8

carry messages from the central nervous system along nerves in the PNS to effectors such as muscles and glands

Question 9

relay neurons

Answer 9

connect sensory and motor neurons together, and also connect to other relay neurones

Question 10

function of a neuron

Answer 10

1. when a neuron is in a resting state, the inside of the cell is negatively charged relative to the outside
   but when it is sufficiently activated by a stimulus, the inside of the neurone becomes positively charged for a split second
2. this rapid switch from negative to positive is depolarisation which creates and electric impulse (action potential) from the axon to the terminal buttons
3. the action potential is generated once depolarisation reaches a certain threshold and is always the same intensity, regardless of the size of the stimulus that generated it
   if the threshold is not reached there is no action potential - action potential is an all or nothing event