Which of the following is NOT a function of the skin?

Hematopoiesis, the process of forming blood cells, primarily occurs in the bone marrow and is not a function of the skin. The skin serves various essential functions, such as providing a barrier against external elements (protection), enabling the absorption of certain substances (absorption), and playing a minor role in respiration, though this is not its primary function. Understanding the specific roles of different body systems helps clarify why hematopoiesis does not take place in the skin, which is primarily involved in guarding against pathogens and regulating temperature. This distinction highlights the specialized nature of blood cell production within the body.