allerySympathetic stimulation of the heart
AIncreases the heart rate and force
BHas no effect on the heart muscle
CStops conduction at the AVN only
DDecreases the heart rate and force
Answer & Solution
Correct answer: A. Increases the heart rate and force
Sympathetic (noradrenaline) acts via beta-1 receptors to raise SAN firing rate (chronotropy), AV conduction (dromotropy) and contractility (inotropy).
Parasympathetic (vagus, acetylcholine) does the opposite, mainly at SAN and AVN.
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