Question

Which of the following is FALSE of sympathetic activity to the SA node?

A) Norepinephrine binds to beta1 adrenergic receptors.
B) cAMP levels in the pacemaker cells increases.
C) Funny channel opening is enhanced.
D) The rate of spontaneous depolarization is increased.
E) Potassium channel closing is enhanced.

Answer 1

The FALSE statement is that potassium channel closing is enhanced. The correct answer is E).

Step-by-step explanation:

The FALSE statement among the options provided is option E) Potassium channel closing is enhanced. Sympathetic activity to the SA node actually causes a decrease in potassium channel opening, not closing. This reduction in potassium channel opening prolongs the duration of depolarization, leading to an increased heart rate. It is important to note that sympathetic activity, including the binding of norepinephrine to beta1 adrenergic receptors and the subsequent increase in cAMP levels, enhances the rate of spontaneous depolarization and the opening of funny channels in the SA node, resulting in an increased heart rate.