Which components are included in the integumentary system?

The integumentary system is primarily composed of structures that serve as protective barriers for the body, and the main components include skin, hair, and nails. The skin is the largest organ in the body and plays vital roles in protection, regulation, and sensation. It acts as a shield against environmental hazards, helps regulate body temperature, and allows for the sensation of touch, pain, and temperature.

Hair and nails, while not part of the skin itself, are derivative structures made of keratin, a protein that provides strength and durability. Hair is involved in protection, insulation, and sensory functions, while nails protect the tips of fingers and toes from injury and enhance the ability to grasp objects.

In contrast, other systems mentioned involve different structures and functions. Muscles and tendons belong to the musculoskeletal system, the heart and blood vessels are central to the circulatory system, and the lungs and airways are part of the respiratory system. Hence, the correct choice clearly identifies the specific components that together constitute the integumentary system.