How does the integumentary system interact with the endocrine system?

The integumentary system interacts with the endocrine system primarily through the synthesis of vitamin D and the regulation of sweat. When skin is exposed to ultraviolet (UV) light from the sun, it converts a cholesterol-derived compound into vitamin D3, which is then modified in the liver and kidneys into its active form, calcitriol. Calcitriol functions as a hormone that plays a crucial role in calcium metabolism and bone health, thereby linking the integumentary system directly with hormonal regulation.

Additionally, the skin's role in regulating sweat involves the endocrine system indirectly through the action of various hormones that influence sweat production. For example, adrenergic hormones can stimulate sweat glands to produce sweat, aiding in thermoregulation. This interaction exemplifies how the integumentary system can impact and modulate physiological processes governed by hormones, making this choice the best representation of their relationship.