QuestionSBA
QuestionChoice
This is correct. Adenosine is an anti-arrhythmic which works by opening potassium channels on cells in the sinoatrial node. This causes hyperpolarisation of the cell, meaning it is further from the threshold potential, therefore lengthening the refractory period and slowing conduction through the node.
10026270
a
It opens potassium channels causing hyperpolarisation
QuestionChoice
This is incorrect. Adenosine is an anti-arrhythmic which works by opening potassium channels on cells in the sinoatrial node. This causes hyperpolarisation of the cell, meaning it is further from the threshold potential, therefore lengthening the refractory period and slowing conduction through the node.
10026274
e
It does not affect potassium channels
QuestionChoice
This is incorrect. Adenosine is an anti-arrhythmic which works by opening potassium channels on cells in the sinoatrial node. This causes hyperpolarisation of the cell, meaning it is further from the threshold potential, therefore lengthening the refractory period and slowing conduction through the node.
10026273
d
It closes potassium channels causing depolarisation
QuestionChoice
Whilst adenosine does cause hyperpolarisation of the sinoatrial node cells, this is done via opening, not closing, potassium channels. Since potassium moves from inside the cell to outside, opening more potassium channels would result in more outward movement and hence further lower the membrane potential of the cell.
10026272
c
It closes potassium channels causing hyperpolarisation
QuestionChoice
Whilst adenosine does open potassium channels, this would result in hyperpolarisation, not depolarisation. Since potassium moves from inside the cell to outside, opening more potassium channels would result in more outward movement and hence further lower the membrane potential of the cell.
10026271
b
It opens potassium channels causing depolarisation
Concept
Chapter
2693
5886
Acute narrow complex tachycardias
Topic
134
Cardiology
17652
What effect does adenosine have on potassium channels in cells in the sinoatrial node?
a