What does the integumentary system consist of?

The integumentary system is primarily composed of the skin and its various appendages, making the combination of skin, mucous membranes, hair, and nails the correct answer. This system serves several vital functions, including protecting the body from external elements, regulating temperature, and allowing sensory interaction with the environment.

Skin acts as a barrier from pathogens and helps in water retention to avoid dehydration. Hair provides thermal insulation and has protective functions, while nails protect the tips of fingers and toes and enhance the ability to grasp objects. Mucous membranes support the integrity of body cavities and organs, further contributing to the protective function of the integumentary system.

In contrast, the other answer options refer to different systems in the body: the brain and spinal cord belong to the nervous system, muscles and bones comprise the musculoskeletal system, and the heart and blood vessels are parts of the cardiovascular system. Recognizing these distinctions is important for understanding the roles and components of each body system.