The skin is the largest organ in the body, it is 12 to 15% of body weight.Two distinct layers occur in the skin: the dermis and the epidermis.
The dermis is a connective tissue layer under the epidermis and contains nervous endings, sensor receptors, capillaries, and elastic fibers. Hair follicles are lined with cells that synthesize the proteins that form hair. Sebaceous gland (secretes the oily coating of the hair shaft), the capillary bed, nerve ending, and small muscles are associated with each hair follicle.If the sebaceous glands becomes plugged and infected, it becomes a a skin blemish. There are two types of sweat glands Eccrine(all over the body) and Apocrine(the ones that produce an odor). All sweat glands open to surface through pores.The integumentary system has multiple roles in homeostasis, including protection, temperature regulation, sensory reception, biochemical synthesis, and absorption. The skin's primary functions are to serve as a barrier to the entry of microbes and viruses, and to prevent water and extracellular fluid loss. Melanocytes form a second barrier: protection from the damaging effects of ultraviolet radiation. When a microbe penetrates the skin the inflammatory response occurs.When the body temperature rises, the hypothalamus sends a nerve signal to the sweat producing skin glands, causing them to release about 1-2 liters of water per hour, cooling the body. The hypothalamus also causes dilation of the blood vessels of the skin, allowing more blood to flow into thse ares, causing heat to be convected away from the skin surface.f5-1_layers_of_the_inte_c.jpg