Signalling

Question 1

typical number of subunits in ion channels

Answer 1

4-5

Question 2

is resting potential closer of potassium of sodium equilibrium potential

Answer 2

potassium due to higher permeability for potassium than sodium at rest

Question 3

graded potentials

Answer 3

localised, temporal changes in membrane potential that are unable to travel
the membrane difference dissipates with distance

Question 4

spatial summation

Answer 4

summation of graded potentials where synapses in one area simultaneously fire

Question 5

temporal summation

Answer 5

summation of graded potentials where one synapse repeatedly fired before graded potential is able to dissipate

Question 6

average threshold potential

Answer 6

around -55mV

Question 7

average resting potential

Answer 7

around -70mV

Question 8

typical membrane potential after hyperpolarisation

Answer 8

around -95mV

Question 9

factors affecting speed of nerve impulse

Answer 9

axon diameter and myelination

Question 10

order of speed to neuron types:
-pain
-sensory
-autonomic

Answer 10

sensory > pain > autonomic

Question 11

saltatory conduction

Answer 11

allowed by presence of myelin sheath around an axon
speeds up travel nerve impulse
areas of myelin are ‘skipped’ while sodium ions are ‘pulled’ to the following node by its electrochemical gradient

Question 12

electrical synapse

Answer 12

gap junctions between neurons, allowing for direct transfer of electrical/chemical changes

Question 13

where are electrical synpases mostly found

Answer 13

in areas where synchronised signalling is required

Question 14

results of EPSPs

Answer 14

opening of potassium and sodium channels (action potential generation/depolarisation)

Question 15

results of IPSPs

Answer 15

opening of either potassium (flow in) or chlorine channels (flow out)

Question 16

methods of neurotransmitter removal

Answer 16

• enzymatic degradation by pre-synaptic neuron
• use of pumps/channels for re-uptake
• use of astrocytes