Sympathetic activation is an example of which chronotropic effect on heart rate?

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Multiple Choice

Sympathetic activation is an example of which chronotropic effect on heart rate?

Explanation:
Sympathetic activation increases heart rate, which is a positive chronotropic effect. Norepinephrine released onto beta-1 receptors in the SA node raises cAMP, activating PKA. This enhances the funny current (I_f) and L-type calcium current, making the diastolic depolarization steeper and speeding up SA nodal firing (and AV nodal conduction). The result is a faster heart rate. The term “inotropic chronotropic” isn’t appropriate here, since inotropic refers to contractility, not rate.

Sympathetic activation increases heart rate, which is a positive chronotropic effect. Norepinephrine released onto beta-1 receptors in the SA node raises cAMP, activating PKA. This enhances the funny current (I_f) and L-type calcium current, making the diastolic depolarization steeper and speeding up SA nodal firing (and AV nodal conduction). The result is a faster heart rate. The term “inotropic chronotropic” isn’t appropriate here, since inotropic refers to contractility, not rate.

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