Skin Thermoregulation Simulator (2D)

This 2D cross-section slices through the skin — epidermis, dermis and fatty hypodermis — to show how the body defends its core temperature. Drag the ambient temperature slider toward heat and the surface vessels widen (vasodilation) while sweat droplets bead and evaporate off the skin; drag it toward cold and the vessels narrow (vasoconstriction) while muscle fibers begin to jitter (shivering) to generate heat. Raising the activity slider adds metabolic heat on top of the ambient temperature, so even a cool room can trigger sweating during exertion. Live readouts track skin blood flow, sweat rate, core body temperature and which thermoregulatory mechanism currently dominates.