Which substances are responsible for regulating heart function?

The correct answer highlights the crucial role that hormones, calcium (Ca2+), and potassium (K+) play in regulating heart function.

Hormones such as epinephrine and norepinephrine are key players in the autonomic regulation of heart rate and contractility. They can increase heart rate and force of contraction by acting on specific receptors in heart tissues, thus modulating cardiac output according to the body’s physiological needs.

Calcium ions are vital for the contraction of cardiac muscle cells. They enter muscle cells during the action potential, triggering a cascade that leads to muscle contraction. The regulation of calcium is essential for maintaining proper heart function, as an imbalance can lead to arrhythmias or impaired contractility.

Potassium levels are equally critical, as potassium ions are essential for maintaining the resting membrane potential of cardiac cells. Proper levels of potassium are necessary for normal electrical conduction and repolarization during a heartbeat. High or low potassium levels can cause significant disruptions in cardiac rhythm.

The other substances listed in the other choices do not play primary roles in the direct regulation of heart function. For instance, while glucose is important for energy metabolism in cardiac cells, it does not directly influence heart function in the manner that hormones and ions do. Similarly, sodium and