Organs of the circulatory system are the heart, blood, and blood vessels (arteries and veins). The circulatory system interacts with other systems, such as the lungs (respiratory system), liver (digestive system), and kidneys (digestive system).
Skin, hair, nails, sweat and oil glands. Function: Serves as a barrier against infection and injury; helps to regulate body temperature; provides protection against ultraviolet radiation from the sun.
General, Non-specific Defenses Against Infection. There are several simple physical and chemical barriers that constitute and important first line of defense. Our skin provides a highly effective barrier to infectious agents despite the fact that skin is colonized by an impressive array of microbial agents.