What hormone is released by heart muscle in response to excessive chamber volume?

The hormone that is released by heart muscle in response to excessive chamber volume is natriuretic peptide. This peptide, specifically atrial natriuretic peptide (ANP), is secreted by the atrial cells of the heart when there is an increase in blood volume, leading to increased pressure and volume in the heart chambers.

The primary function of natriuretic peptide is to promote natriuresis, which is the excretion of sodium through the urine, and to reduce blood pressure by causing vasodilation. It counteracts the effects of other hormones that raise blood pressure, such as aldosterone and angiotensin, thereby maintaining fluid balance and homeostasis.

In conditions of fluid overload, such as heart failure, the elevated levels of natriuretic peptide can be a response to the heart's attempt to reduce strain and help prevent further complications associated with increased volume. Understanding this physiological process underscores the importance of natriuretic peptides in regulating cardiovascular function and fluid balance in the body.