The Integumentary System Skin, Hair & Nails

The System Skin, hair and nails make up the integumentary system These structures are made of a protein called keratin.

The Skin The largest organ of the body Integument means “skin” and comes from the Latin word meaning “to cover”

2 Layers of the Skin 1. Epidermis Outer layer of the skin made of dead cells Shed every 4-5 weeks Contains no blood vessels Pores allow sweat and oil to escape Contains melanocytes which make dark skin pigment melanin

2 Layers of the Skin

2 Layers of the Skin 2. Dermis Inner layer of skin, lies beneath the epidermis Contains blood vessels, nerve endings, glands, sensory receptors, & hair follicles

Glands found in the Dermis Sweat glands Produce sweat when your temperature rises too high or when under stress Sweat contains salts, water, and other compounds Sweat helps rid the blood of wastes Sebaceous glands Produce an oily secretion called sebum Sebum spreads along the surface of the skin keeping it flexible and waterproof

Below the Skin Region below the dermis is called hypodermis or subcutaneous tissue Fatty tissue which stores fat and anchors skin

Functions of Skin Barrier against infection and injury Regulates body temperature Removes waste products Protection against UV rays from the sun Sensory receptor for pressure, heat, cold & pain

Temperature Regulation When it’s cold, the blood vessels in the dermis will contract, limiting heat loss. On hot days, blood vessels will dilate (widen) bringing the heat from the body’s core to the surface to be released. Sweat released from glands evaporates to cool the skin.

Barrier against pathogens Regulates temperature Protects against UV rays Removes wastes

Hair Covers almost every exposed surface of the body Hair protects the skin from UV rays and insulates when cold by standing up (arrector pili muscle) Hair in the nostrils, ears, and eyelashes helps prevent dirt and pathogens from entering the body.

Nails Protect fingertips and help in picking up small objects Correspond to hooves and claws in other mammals.

Skin Cancer Associated with exposure to sun (UV rays) Melanoma is the deadliest type; uncontrolled growth of melanocytes.

Pore Epidermis Sebaceous gland Melanocytes Sweat gland Dermis Hair follicle Arrector pili muscle Blood vessels Nerve ending Hypodermis