undirhúð

Undirhúð, also known as the hypodermis or subcutaneous layer, is the deepest layer of the integumentary system, situated beneath the dermis. It primarily consists of loose connective tissue and adipose tissue, which is fat. This layer plays a crucial role in insulating the body, cushioning underlying organs, and storing energy in the form of fat. The thickness of the hypodermis can vary considerably depending on factors such as age, sex, and body region, being generally thicker in women and in areas where fat is stored.

The hypodermis serves as an anchor for the skin to the underlying muscles and bones, while also allowing for some degree of movement. It contains blood vessels that supply nutrients to the dermis and hypodermis, as well as lymphatic vessels and nerves. The adipose tissue within the hypodermis is metabolically active and contributes to thermoregulation by reducing heat loss. It also acts as a shock absorber, protecting the body from physical trauma. In some contexts, the hypodermis is considered a separate organ due to its distinct structure and functions, although it is typically discussed as part of the skin. Its composition and distribution are vital for overall body composition and metabolic health.