Finally, E-1173 arrived at its destination: a sleepy capillary bed in the gastrocnemius muscle of a jogging human. The environment here was hostile. The local pH was acidic from lactic acid. The temperature was high from muscular work. CO₂ partial pressure was elevated. All of these factors—the —were chemical insults screaming, “Unload your oxygen!”
And so, the story of medical physiology is not about one cell, but about the relentless, integrated, and beautiful logic of systems working in concert. It is the story of how the body, every second of every day, reads its internal environment and makes it right. fundamentals of medical physiology