We learned about the integumentary system which is made up of toenails, fingernails, hair, and the largest organ in the body, the skin. We learned that blood vessels near the surface of the skin help cool your blood and that hair helps keep your head warm. Some of the functions of skin are to protect from germs and keep water inside. We learned that friction ridges are the circles on your fingertips which are more sensitive to touch then other places on your body. Next we learned that the epidermis is the outer skin and dermis is the inner skin layer that contains hair follicles, sweat glands, blood vessels, and nerve endings.