Which of the following is a metabolic function of skin?
A. body temperature regulation
B. synthesis of a vitamin D precursor
C. elimination of nitrogenous wastes
D. cutaneous sensation
The Correct Answer and Explanation is:
The correct answer is B. synthesis of a vitamin D precursor.
Explanation:
The skin plays several important roles in the body, and one of its crucial metabolic functions is the synthesis of a vitamin D precursor, specifically cholecalciferol (vitamin D3). This process begins when the skin is exposed to ultraviolet (UV) radiation from sunlight. The epidermis contains 7-dehydrocholesterol, which is converted to previtamin D3 upon exposure to UV light. This compound is then transformed into vitamin D3 through a heat-dependent process. Once synthesized, vitamin D3 is transported to the liver and kidneys, where it is converted into its active form, calcitriol, which is vital for calcium absorption and bone health.
While the skin does contribute to other functions mentioned in the options, they are not classified as metabolic functions. For example, A. body temperature regulation involves thermoregulatory mechanisms, including vasodilation and sweating, rather than metabolic processes. C. elimination of nitrogenous wastes occurs through sweat but is not a primary function of the skin; the kidneys are primarily responsible for waste excretion. D. cutaneous sensation refers to the skin’s ability to perceive stimuli through nerve endings and does not involve metabolic activity.
In summary, the skin’s role in synthesizing vitamin D is a critical metabolic function that affects overall health. It highlights the skin’s importance not only as a protective barrier but also as an active participant in various physiological processes. Adequate exposure to sunlight is essential for maintaining sufficient vitamin D levels, which, in turn, supports numerous metabolic functions, including the regulation of calcium and phosphorus, essential for bone and immune health.