Parasympathetic stimulation of the heart generally leads to a decrease in heart rate,because acetylcholine
A) increases intracellular cAMP levels and opens calcium channels.
B) opens potassium channels allowing potassium ion efflux.
C) binds and blocks b receptors on the cell membrane.
D) inhibits voltage-gated sodium channels in the membrane.

Question

Quizplus · Accepted Answer

Acetylcholine is the neurotransmitter released by parasympathetic nerve endings.Acetylcholine binding to muscarinic receptors on heart cells inhibits cAMP production,and increases membrane permeability to potassium ions allowing them to leak from the cell.Intracellular cAMP levels are decreased while potassium is allowed into the cell.b Receptors on heart muscle cell membranes increase the production of cAMP.Autonomic neurotransmitters inhibit voltage-gated sodium from entering the membrane.

Parasympathetic Stimulation of the Heart Generally Leads to a Decrease