Integumentary System Scratching the Surface
Our Largest Organ… • Major functions include: • Protection – prevents chemical and physical injury • Sensory response • Vitamin D formation • Regulate body temp. • Rids the body of waste
Contains 3 layers Epidermis Dermis Subcutaneous (fatty) layer
Epidermis • The thinnest, outermost layer • Epidermis cells are constantly being replaced • Produces the chemical melanin • A pigment that protects your skin and gives it color. • Production increases when exposed to UV rays and skin becomes darker • Darker skin = greater protection
Dermis and Subcutaneous • Dermis • Thicker layer located directly below the epidermis • Contains blood vessels, nerves, muscles, oil and sweat glands • Subcutaneous • Below the dermis • Fatty region that insulates the body • Where most fat is deposited when we gain wait.
Vitamin D Formation • Small amounts are produced in the presence of UV light. • Vitamin D helps your body absorb calcium into your blood from food in your digestive tract.
Heat Exchange • Blood vessels help release or hold heat • When they dilate (expand) blood flow increases and heat is released • When they constrict (shrink) blood flow decreases and less heat is released
Heat Exchange • Sweat glands • When blood vessels dilate, pores open in the skin that lead to sweat glands • Perspiration moves out onto the skin, and heat transfers from the body to the sweat on the skin
Waste Exchange • Sweat glands also release waste products produced by your cells • Water, salt, and other organic wastes • If too much water and salt are released, you can become dehydrated
Injury and Repair • Bruises (contusions) • Tiny blood vessels under the skin burst • Red blood cells leak into the surrounding tissue • Hemoglobin from the red blood cells begins to breakdown into different pigments, giving bruises their different colors Broken down blood returns to bloodstream
Injury and Repair • Cuts • Any tear in the skin • Blood clots and forms a scab • Surrounding cells fight off infection • Skin cells beneath the scab grow to fill the gap in the skin • Scars may result from thick tissue fibers if a cut is too deep.
Injury and Repair • Skin grafts • Pieces of skin that are cut from one part of the body and moved to cover the injured area • Nearby blood vessels keep the grafted skin alive • Used when not enough skin cells are left