Final answer:
Atrial natriuretic peptide (ANP) is a heart hormone that reduces blood volume and pressure by promoting the excretion of sodium and water through the kidneys. It acts antagonistically to aldosterone, which seeks to retain sodium and water in the body.
Step-by-step explanation:
The atrial natriuretic peptide (ANP) is a hormone produced by the heart that has important regulatory functions in the body's fluid balance and blood pressure. This hormone is released by specific cells in the atria of the heart when there is elevated blood volume, leading to the stretching of these cells. ANP exerts its effects by acting on the kidneys, promoting the excretion of Na+ and water, leading to a reduced blood volume and blood pressure. Moreover, it suppresses the production and release of renin, aldosterone, and ADH (antidiuretic hormone), which are all factors that contribute to water retention in the body.
In direct response to the student's question, ANP functions antagonistically to B. aldosterone. While aldosterone promotes sodium and water reabsorption in the kidneys to increase blood volume and pressure, ANP does the opposite by promoting the loss of sodium and water to decrease blood volume and pressure.