Integumentary System

People are often interested in the appearance of their skin but rarely consider its functions. The integumentary system serves many purposes, including these important functions:

·         Protection- as long as the skin is intact and not inflamed; it is our first line of defense against the entry of bacteria and viruses. It also protects underlying structures from ultraviolet radiation and dehydration.

·         Body temperature regulation- skin plays a major role in regulating body temperature. When a person is hot, dermal blood vessels are more dilated so more blood pass through the skin. This is beneficial because blood carries a lot of the heat in the body. When the blood gets close to the skin the skin, the heat can escape. If someone is cold, the dermal blood vessels constrict, preventing the heat in the blood from escaping.

·         Vitamin D production- when exposed to sunlight, the skin produces a molecule that is turn into vitamin D. The body needs vitamin D for calcium absorption.

·         Sensation- the skin is packed with sensory receptors that can detect touch, heat, cold, and pain.

·         Excretion- small amounts of waste products, such as water and salts, are lost through skin when a person perspires. This is why hydration is so important when exercising or during exposure to high temperature, when the amount of perspiration increased and higher amounts of water and salts are lost.

The topmost layer of the skin is the epidermis. The dermis is the complex middle layer. The innermost layer attaching the skin to muscle is subcutaneous layer. The most common cell type in the epidermis is the keratinocyte. Keratin is a durable protein that makes the epidermis waterproof and resistant to bacteria and viruses.  Another cell type is the melanoctye , which makes the pigment of melanin and the amount of melanin you have in your skin makes up your skin color. The dermis contains sudoriferous (sweat) glands, sebaceous (oil) glands, hair follicles, the arrector pili muscles, collagen fibers, elastin fibers, nerve fibers, and many blood vessels. The subcutaneous layer of the skin or hypodermis, is largely made of adipose and loose connective tissue.