Do nerve cells cause action potential in cardiac muscle?

Question

I think the answer is no, but I am not 100% sure.

If it was yes, then the dendrite of the nerve cell should each time receive a stimulus causing Na+ channels to open, when the contraction happen. Also, then it would mean that outside events could alter the function of hearth, which would be dangerous.

The heart has a special excitatory system and a contractile system - Sinoatrial node and Pacemaker cells, which control the action potentials in different portions of the heart. So heart and primarily myocardium i.e. cardiac muscle can depolarise without any external influence with a slow, positive increase in voltage across the cell's membrane.

Do nerve cells cause action potential in cardiac muscle?

Answer 1

The vagus nerve controls heart rate. This is the best example of a direct nerve action potential impacting cardiac muscle, although one could argue the adrenaline system to be an indirect mechanism.

The vagus nerve is part of the parasympathetic system, it acts to decrease heart rate. Resting heart rate is maintained by permanent vagal stimulation/tone by the release of acetylcholine.

Answer 2

Heart cells will contract on their own without the presence of nervous tissue. If you place small pieces of fresh heart tissue in a Petri dish in a proper solution, they will contract on their own at a frequency somewhat slower than a regular heartbeat. But the pieces may contract independently of one another.

The purpose of stimulation from the vagus nerve is to act like an orchestra conductor causing the contractions of individual cells to act in a coordinated manner.