Major roles of the Integumentary System  protection  maintenance of normal body temperature  storage (of fat)  synthesis (of vitamin D)  excretion (of salts, water and wastes in sweat)  sensory perception

The Skin: 3 Major layers

Did You Know?...  At 8-10 pounds, the skin is bodies largest organ!

The Epidermis  The epidermis is the outer layer of skin. The thickness of the epidermis varies in different types of skin. It is the thinnest on the eyelid at.05 mm and the thickest on back at 1.5 mm.  Cells of the epidermis are constantly shedding off and replacing themselves…

Which layer of the epidermis is this?

The Dermis  This layer varies in thickness as well, depending on the area of the body. It is a mere 0.3 mm on the eyelid and 3.0 mm on your back.  The dermis is composed of tissue….

Dermis Tissue: Collagen  Collagen is the most abundant and important structural protein in your body. It strengthens and supports many body tissues from the outside creating an “extracellular matrix.”

1 Square inch if Skin Contains…

What makes these hairs stand on end? Why?

Layer 3: The Subcutaneous  Also referred to as the “hypodermis,” this layer of the skin is composed primarily of adipose tissue (fat). This layer plays a key role in insulating the body and regulating the temperature of the skin.  The hypodermis can vary significantly in thickness and incorporates larger blood vessels and nerves.

Nails  Your nails extend from the epidermis and contain a tough protein called keratin. They play an important role in grasping objects, scratching, and protecting fingers and toes.

A. Nail plate; B. lunula; C. root; D. sinus; E. matrix; F. nail bed; G. hyponychium; H. free margin

Did you Know?  Your fingernails grow about 5 times faster than your toenails!

Hair  Also composed of the protein keratin hair acts as an effective insulator between you and the environment.  hair follicles originate in the dermis.

Did you know?  Humans have more hair than apes. Although theirs is thicker, longer, and typically darker.

Challenge Question!  The hair in your ears, nose, and around your eyes play important roles in keeping you healthy….Can you explain why?

Did You Know?  Hair can grow as little as 0.1 inches per month or as fast as 0.5 inches per month depending on genetics and your diet.

Damaging the Skin Abrasions are commonly called scrapes. They occur when the skin is rubbed across a rough surface. Abrasions involve variable depths of skin. Puncture wounds are caused by a sharp object that penetrates the skin. Such wounds may cause significant deep injury that is not immediately recognized. These types of wounds do not bleed freely The most common type of open wound is a laceration. Lacerations are commonly called cuts and are an irregular cut or tear through the skin. An avulsion is a tearing away of body tissue. Avulsions raise flaps of tissue, usually along normal tissue planes. The avulsed part may be totally severed from the body or it may be attached by a flap of skin.

Disorders of the skin Lesions and tumors infections (bacterial, viral, fungal, parasitic) inflammatory reactions and allergies Genetic diseases acne

Anatomy of a Pimple