Following an intense workout your clothes are drenched in sweat.You estimate you lost at least 0.5 L of sweat.Your (similarly sized)friend skipped her workout to donate blood and you found out she donated 0.5 L of plasma.After these activities,which of you will have a greater increase in vasopressin secretion and why?

Question

Quizplus · Accepted Answer

Sweat is generally hypoosmotic compared to plasma, meaning it has a lower concentration of solutes. When you lose hypoosmotic fluid through sweating, your body's remaining extracellular fluid becomes more concentrated. This increase in osmolality stimulates the secretion of vasopressin (also known as antidiuretic hormone or ADH) to promote water reabsorption in the kidneys and help restore fluid balance. In contrast, donating blood removes a volume of isosmotic fluid (plasma), which does not immediately alter the osmolality of the body fluids. Therefore, the loss of hypoosmotic sweat would lead to a greater increase in vasopressin secretion compared to the isosmotic loss of plasma through blood donation.

Following an Intense Workout Your Clothes Are Drenched in Sweat