Sweating and Skin Blood Flow Changes during Progressive Dehydration

Unfortunately, in situations of protracted and high sweat secretion, the body water content will become progressively reduced, and the blood volume slowly declines. This is well tolerated within healthy individuals. However, the regulation of blood pressure has a higher homeostatic priority than does temperature regulation, since low pressures cannot support adequate tissue perfusion, and will eventually result in cell damage, regardless of tissue temperature. Therefore, a chronotropically and inotropically mediated increase in cardiac output ensues, simultaneously with an elevation in total peripheral resistance. Vasoconstriction is initially directed towards the visceral structures, but as the body water deficit becomes greater, constriction can also be expected within the cutaneous vascular beds to ensure that blood pressure is not compromised. When this occurs, sweating may also be impaired, and an undesirable elevation in body heat storage can result.