What is the primary function of the integumentary system?

The integumentary system primarily serves to protect the body and regulate temperature. This system includes the skin, hair, nails, and associated glands, which together play a critical role in safeguarding the body's internal structures from external harm, such as pathogens, UV radiation, and physical injury. The skin acts as a barrier, preventing the entry of harmful microorganisms and chemicals.

In addition to protection, the integumentary system is vital for thermoregulation. Through mechanisms such as sweating and vasodilation, the skin helps maintain a stable internal body temperature regardless of external environmental conditions. This is essential for the proper functioning of various physiological processes.

The other options pertain to different systems and functions of the body. For example, digestion and nutrient absorption are primarily the roles of the digestive system, while transport of oxygen and nutrients is the function of the circulatory system. Movement is facilitated by the muscular and skeletal systems. Thus, while all these functions are crucial for overall health, the integumentary system's primary function is distinctly about protection and temperature regulation.