What function does blood serve in the dermis?

The function of blood in the dermis is crucial for maintaining the health and vitality of the skin. One of the key roles blood plays is to nourish the skin cells by delivering essential nutrients and oxygen. This is vital for cellular metabolism and overall skin function. Additionally, blood flow in the dermis assists in regulating temperature. When the body overheats, blood vessels dilate (a process known as vasodilation), allowing more blood to flow to the skin's surface, facilitating heat loss through the skin. Conversely, when body temperature drops, blood vessels constrict (vasoconstriction), reducing blood flow to conserve heat.

In contrast, while blood supports various skin structures, including hair follicles, and is involved in waste removal, these functions are secondary to its primary roles in nourishment and temperature regulation. Blood does not directly produce keratin; that process occurs in specialized skin cells called keratinocytes in the epidermis, which rely on nourishment from the dermis. Thus, the comprehensive role of blood in nourishing the skin and regulating temperature makes it the most fitting answer.