In which part of the heart is ANP produced?

Atrial Natriuretic Peptide (ANP) is produced in the atria of the heart. This hormone is synthesized and secreted by the specialized cells located in the atrial tissue. It plays a critical role in the regulation of blood pressure and fluid balance in the body. When the atria are stretched due to increased blood volume, they release ANP, which promotes vasodilation and sodium excretion by the kidneys. This action helps to lower blood pressure and reduce blood volume, illustrating the body's feedback mechanism to maintain homeostasis.

In contrast, the ventricles primarily pump blood out of the heart and are not involved in the production of ANP. The septum is the wall dividing the left and right sides of the heart, and it also does not produce hormones. The valves are structures that ensure unidirectional flow of blood and do not have any hormonal functions. Therefore, the correct association of ANP production with the atria highlights its physiological role in responding to changes in blood volume and pressure.