Question

An individual has a higher-than-normal blood volume, solely due to excess water—not high enough to cause symptoms, but enough to cause the body to attempt a restoration to normal levels. Describe all processes by which the body induces the decrease of blood volume. Your response should include a review of all body cells and structures capable of detecting high water levels (whether directly or indirectly), the body responses that stimulate water excretion, and all processes for the removal of water from the body. Please note that while some parts of your response should be similar to that of response #3, there should be many more differences than similarities.

Answer 1

When there is volume overload solely due to excess of water, this Increased volume is sensed by the walls of the right Ventricle which lead to secretion of Atrial Natutrtic Peptide (ANP) & Brain naturetic peptide.

ANP act on the Affernet arteriole of kidney and lead to Arteriolar dilation and hence Increases glomerular blood flow. This Increases Glomerular capillary hydrostatic pressure which is responsible for more Filtration and Increased GFR.

ANP also act upon the Collecting duct of nephron and prevent reabsorbtion of sodium from the nephron. Hence, with loss of Na in urine, water is also lost in urine, called as naturesis.

Both ANP and BNP inhibit the release of Renin hence decreses aldosterone. This reduced aldosterone further prevent salt and water reabsorption from the DCT. Hence it increases the naturesis.

In this way the body returns it fluid balance.