Which of the following processes is not a function of the mammalian skin?

Gaseous exchange is not a function of mammalian skin. Mammalian skin is made up of multiple layers, with the outermost layer being the epidermis, which is impermeable to gases. Therefore, it cannot facilitate gaseous exchange. Instead, gaseous exchange in mammals occurs through the respiratory system, which includes the lungs and associated structures. In contrast, the other options mentioned are all functions of the mammalian skin. The skin helps regulate body temperature through processes such as sweating and blood vessel dilation/contraction. The skin also contains sensory receptors that allow for the reception of external stimuli such as touch, pressure, and temperature. Additionally, the skin can excrete waste products such as salts, water, and small amounts of urea through sweat glands.