Which system protects the body from disease by acting as a barrier to pathogens?

The integumentary system is the correct choice because it serves as the first line of defense against pathogens. This system includes the skin, hair, nails, and various glands. The skin acts as a physical barrier that prevents pathogens from entering the body, while also playing a role in the immune response through its various immune cells.

The integumentary system also produces antimicrobial substances that inhibit microbial growth, contributes to wound healing, and regulates temperature, which can impact the body’s overall health and ability to fend off infections. The presence of the outer layer of skin, specifically the epidermis, shields underlying tissues from environmental pathogens, making it crucial in protecting the body from disease.

In contrast, while the immune system is directly responsible for identifying and combating pathogens, it works in conjunction with the integumentary system rather than serving as a physical barrier. The cardiovascular system is primarily involved in transporting blood and nutrients throughout the body, and the respiratory system is focused on the exchange of gases, not directly protecting from pathogens in the same manner as the integumentary system.