A Lethal Overload Problem

(As always in these posts, my presentation of the facts about our body’s physiology is purposely brief. I do hope, however, that my posts will stir the reader to independent research).

Fixing a Lethal Fluid Overload Problem

There are several reasons our blood vessels can become overloaded with fluid – blood products and water, primarily. The reasons for the overload are beyond the scope of this post, but the point is, unless the body compensates for the fluid overload, we will die.  

Two body mechanisms which help the body compensate are found in the heart muscle itself – specifically the atria (the top left and right chambers of the heart), and the ventricles (the bottom two chambers). In response to atrial or ventricular filling, the heart muscle secretes specific hormones. The atrial hormone is called the ‘atrial natriuretic polypeptide’ (ANP). The ventricular hormone is called the ‘brain natriuretic polypeptide’ (BNP). Why it is called ‘brain natriuretic polypeptide’ is also beyond the scope of this essay.

It is important to know that the heart chambers secrete their hormone into the circulation regardless whether the chambers are being filled to their normal stretch – or to an abnormally high stretch, as occurs in fluid volume overload.

When ANP and BNP reach the kidneys, the kidneys react by excreting as much urine as necessary to compensate for the circulating fluid volume. Consequently, fluid volume is reduced to safe levels, protecting the heart and other body organs.

Lucky for us, either the eons-slow evolutionary processes finally fixed this lethal problem – or God suddenly created the first man and woman with those safety mechanisms already in place.