neurons, reflex arc and synaptic transmission

Question 1

sensory neurons

Answer 1

carries messages from receptor to CNS through PNS
unipolar - only transmits messages
dendrites
short axon
cell body in middle

Question 2

relay neurons

Answer 2

transmits messages between sensory and motor neurons
located in CNS
multipolar - sends and receives messages
many branched and short dendrites
long axon
cell body near dendrites

Question 3

motor neurones

Answer 3

carries messages from CNS to effector
multipolar - sends and receives messages
short dendrites
long axon
cell body in dendrites

Question 4

the process of synaptic transmission

Answer 4

1. action potential travels down axon
2. action potential reaches pre-synaptic neuron
3. triggers release of neurotransmitter
4. neurotransmitters fired into synaptic cleft
5. binds with receptors on dendrite
6. taken up by post-synaptic neuron
7. action potential fired again

Question 5

inhibitory neurotransmitters

Answer 5

decrease likelihood of new action potential forming in postsynaptic cell
when detected by receptors in post-synaptic cell, inhibitory neurotransmitters make electrical charge inside more negative so less likely to fire (hyperpolarisation) - potassium ions leave post-synaptic cell

Question 6

exhibitory neurotransmitters

Answer 6

increase likelihood of new action potential forming in post-synaptic cell
when detected by receptors in postsynaptic cell, exhibitory neurotransmitters make electrical charge inside more positive and more likely to fire (depolarisation) - sodium ions enter postsynaptic cell

Question 7

summation

Answer 7

the combined effect of all excitatory and inhibitory neurotransmitter influences on the postsynaptic neurone
if threshold is reached then a new action potential will form in postsynaptic cell