Why do we sweat?
One of the challenges I give my students early in the year is to describe how a molecule of water moves from the mouth to a muscle cell in the arm. The goal of this exercise is for the students to be able to demonstrate their understanding of the three fluid compartments in the body: plasma (the non-living part of the blood), interstitial fluid (the fluid that surrounds cells) and intracellular fluid (the fluid inside cells). Students can reliably get the water to the stomach, but then struggle to complete the process. We know that fluid moves throughout our body and that some of the fluid stays in our body and some is lost through sweat, urine, feces and breathing. The precise mechanisms by which this happens are a little tricky and exposing students to this process enables them to gain a greater understanding of how difficult it is to maintain homeostasis generally. One of our common experiences is that we sweat when we exercise or are in hot weather. We all know that the s