The Integumentary System Principles of Health Science Unit 6:3

Intro-The Integumentary System Integumentary means “skin” or “covering” It is the largest organ in the body The average person’s skin weighs 10 pounds and has a surface area of almost 20 square feet. Consists of the skin, hair, nails, glands, and nerves It sheds constantly 24/7 and are replaced by new skin cells. Its main function is to act as a barrier to protect the body from the outside world, to retain body fluids, protect against disease, eliminate waste products, and regulate body temperature.

3 Main Layers of Skin Epidermis-outermost; sheds Dermis-center; contain papillae Hypodermis or subcutaneous layer; fatty part and connects to muscle

7 Functions of the Skin Your skin performs the following functions: Protection: from the sun’s UV rays, against invasion by infectious germs, prevents deeper tissues from drying out. Sensory perception: the nerves in the skin help the body respond to pain, pressure, temperature, and touch. Body Temperature regulation: Protects the body against abrupt changes in temperature Storage: stores fat (adipose), water, vitamins and salts Absorption: certain substances can be absorbed through the skin such as medications called transdermal medications. Excretion: helps eliminate salt and excess water and heat through perspiration Production: produces Vitamin D from the ultraviolet (UV) light striking the skin which is an essential vitamin necessary for the absorption of calcium from food and sun.

Temperature Regulation Body temperature regulation If too hot Dermal blood vessels dilate Vessels carry more blood to surface so heat can escape If too cold Dermal blood vessels constrict Prevents heat from escaping

Skin Color Human skin color is controlled by the interaction of 3 pigments: melanin, carotene, and hemoglobin. Melanin is a brown or black pigment produced by melanocytes to protect the skin from UV radiation and gives skin its tan or brown coloration and provides the color of brown or black hair. Melanin production increases as the skin is exposed to higher levels of UV light resulting in tanning of the skin. Carotene is another pigment present in the skin that produces a yellow or orange cast to the skin and is most noticeable in people with low levels of melanin. Hemoglobin is another pigment most noticeable in people with little melanin. It is the red pigment found in red blood cells, but can be seen through the layers of the skin as a light red or pink color.

Diseases and Abnormal Conditions (See pages 116-117) The skin is an organ that is susceptible to disease and abnormalities. Examples: Cancer-malignant and benign Dermatitis-inflammation of the skin caused by irritants Athletes foot-contagious fungal infection of the feet Eczema-inflammation skin disorder caused by an allergen or irritant and can be triggered by stress. Psoriasis-white and flaky usually inherited (chronic) Impetigo-contagious caused by strep infection Ringworm-contagious fungal infection in skin and scalp

Vocabulary Follicles-a hollow tube that contains the root of the hair Hair-helps protect the body and found everywhere except the bottoms of your feet and your palms. You have several million hair. Nails-help protect your fingers and toes from injury. The nail will regrow only if the nail bed is not damaged. Sudoriferous glands-are the “sweat glands” found in the dermis contain salt, water, and other body wastes that you perspire Sebaceous glands-are the oil glands that open up with the hair follicles They produce “sebum” that keeps the skin from drying out It is an antifungal and antibacterial oil that helps prevent infections If it becomes clogged then a pimple or a blackhead is formed.

Other Vocabulary Alopecia-baldness Albino-the absence of color pigment of the skin Jaundice-a yellow discoloration of the skin Cyanosis-blue skin