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.
Physical Barriers of the Body. The physical barriers on the surface of the body play a significant role in slowing or blocking microbial invasion. Very few microorganisms can penetrate intact skin; instead, invaders usually enter through wounds or by being injected, such as by mosquito bites. Skin wounds heal rapidly to reestablish the protective barrier.