1. The Integumentary System The skin is the body’s largest organ Each square inch of human skin consists of twenty feet of blood vessels.

2. The Integumentary System

3. It’s the Skin We’re In! The epidermis is the topmost layer. It helps to prevent evaporation of water from the body and to protect the internal layers from harm. The dermis is the middle layer. It contains the blood vessels, nerves, hair roots, and sweat glands. The subcutaneous tissue is the deepest layer. It contains fats and connective tissue along with large blood vessels and nerves. Why do fingers and toes wrinkle in the bathtub?

4. The Integumentary System

5. It’s a Hairy Situation! Hair color is determined by the amount and type of melanin present. Melanocytes become less active with age. Gray hair is a mixture of pigmented and non-pigmented hairs. Red hair results from a modified type of melanin that contains iron. The shape of the hair shaft determines texture. Round shaft – straight hair Oval shaft – wavy hair Flat shafts – curly or kinky hair Alopecia is the term for hair loss. Why do we get goose bumps when it is cold? Why do men have to shave everyday?

6. The Integumentary System

7. How much do we sweat in a day? Don’t sweat it! Sebaceous glands or oil glands secrete the sebum an oily product. Sebum is usually secreted into a hair follicle. Sebum is a natural skin cream: it helps hair from becoming brittle, prevents excessive evaporation of water from the skin, keeps the skin soft and contains a bactericidal agent that inhibits the growth of certain bacteria. Eccrine glands are the most common sweat gland. They produce sweat, a watery mixture of salts, antibodies and metabolic wastes. Sweat prevents overheating of the body and thus helps regulate body temperature.

8. The Integumentary System

9. Red, Yellow, Black or White The red and yellow hues of the skin are due to hemoglobin in the red blood cells, which pass through the capillaries beneath the epidermis, and carotene (yellowish pigment), which accumulates in fat cells found in the dermis and hypodermis The brown in skin color is due to melanin, which is produced in the skin itself in cells called melanocytes. These cells are located in the epidermis. Melanin protects the chromosomes of mitotically active basal cells against light-induced damage

10. Malfunctioning Melanocytes Albinism – melanocytes completely fail to secret melanin. Hair, skin, and iris are white. Vitiligo – loss of pigment in certain areas of the skin producing white patches. Freckles and moles are formed when melanin becomes concentrated in local areas. Malignant melanoma – a cancerous change in a mole that may metastasize (spread) rapidly and is most difficult to treat. Exposure to sunlight increases risk. What can cause a baby to turn orange?

11. The Integumentary System

12. Guiness Book of Records

13. Functions of the Skin Protection Barrier Function Resistance to wear and tear Vitamin D Production Protection from UV light Sensations Temperature regulation Red with embarrassment! White from fright!

14.  You have approximately 19,000,000 skin cells on every square inch of your body.  Humans shed about 600,000 particles of skin every hour – about 1.5 pounds a year.  House dust is mainly skin flakes!  Skin weighs about 2.5 kilograms - the largest organ in the body.  What hurts if you pull it, but doesn't hurt if you cut it? Your hair, of course!  Skin is elastic - it springs back into shape when stretched. Some medicines (estrogen, nicotine) can pass through the skin, but others cannot (insulin). This is because only fat-soluble substances can enter the skin, not water-soluble ones.  Skin grows faster than any other organ and continues to grow throughout our lives.