Section ii internal environment and homeostasis Total body water=60%o Bw Extracellular fluid Blood plasma 1/5 1/3 Interstitial fluid 4/5 Intracellular fluid 2/3 400BW8 Section II Internal Environment and Homeostasis Interstitial fluid Blood Plasma Intracellular fluid Total body water = 60 % BW = 40 % BW Extracellular fluid 2/3 1/3 1/5 4/5