Signalling

Question 1

Describe how action potentials occur

Answer 1

Na channels open in response to a stimulus causing depolarisation, when it reaches threshold it causes an action potential

Question 2

Define absolute refractory period

Answer 2

No action potential can fire, Na channels are inactive

Question 3

Define relative refractory period

Answer 3

Action potentials can fire but require a higher threshold

Question 4

How does myelination improve conduction

Answer 4

Increase membrane resistance, Lower membrane capacitance

Question 5

Describe how neurotransmitters are released

Answer 5

Depolarisation opens Ca channels, Activates synaptotagmin, SNARE complex forms fusion pore

Question 6

4 types of receptors

Answer 6

Membrane bound with integral ion channels, Membrane bound with integral enzyme activities, Membrane bound with no enzyme activity or ion channels, Intracellular

Question 7

Describe the synthesis of ACh

Answer 7

Formed from choline and acetyl - CoA, catalysed by choline acetyltransferase

Question 8

Describe the synthesis of noradrenaline

Answer 8

Tyrosine converted to Dopa, to dopamine, to noradrenaline

Question 9

Describe how ACh is removed from the synaptic cleft

Answer 9

Broken down to acetate and choline by acetylcholine esterase, choline taken up by high affinity uptake system

Question 10

Describe how noradrenaline is removed from the synaptic cleft

Answer 10

Broken down by monoamine oxidase, taken up by uptake 1