Understand Skin Color and Functions

1. Integumentary System

2. Skin color • All humans have roughly the same number of melanocytes. Color is based on the activity, not the number. • Increase in Melanin production in those exposed to more UV radiation, decreased Melanin production in those exposed to less UV radiation • Melanin is a “natural suncreen”. Dark skinned people seldom have skin cancer due to its effectiveness, however when they get it, it is more deadly.

3. Skin color • Tanning is the body’s built in protective mechanism, it leads to increased melanin production and protection from UV radiation. • Albinos genetically can’t produce melanin and have to be extremely cautious about exposure to the sun. • Skin color is controlled by many factors: • Amounts and kind of pigment present • Amount of carotene present • Amount of oxygen bound to hemoglobin • Emotional stimuli

4. Skin Color • Cyanosis- when blood is poorly oxygenated and skin appears blue • Redness- can indicate embarrassment, fever, hypertension, inflammation or allergy • Pallor (paleness)-emotional stress(fear, anger), anemia, low blood pressure, impaired blood flow into the area • Jaundice (yellow)-liver disorder • Bruises (black and blue)-blood escapes circulatory system and clots in tissue spaces. • Hematomas-unusual bruising-VitaminC deficiency or hemophilia are common causes

5. Skin Appendages • Sebaceous Glands-oil glands, found everywhere but palms of hands and soles of feet • Sebum-mixture of oily substances and fragmented cells, keeps skin soft, prevents brittle hair, kills bacteria. • During adolescence hormones increase amount of oil produces and skin is oilier at that time in life. • Acne is infection of the sebaceous glands • “Cradle cap” is due to overactive sebaceous glands in infants. Yellow brown crust, comes off as dandruff.

6. Sweat Glands • 2 kinds of sweat glands (Sudoriferous glands) • Eccrine- produces primarily water, it is odorless and actually inhibits bacterial growth. Helps body regulate temperature. You can lose 7L of water on a hot day • Apocrine-produces fatty acids and proteins which provides a food source for bacteria on skin. The by-product of those bacteria is body odor. • Sweat reaches the skin by a duct that opens as a pore.

7. Hair • Functions: • Guards head against bumps • Eyelashes protect the eyes • Keeps foreign particles out of respiratory tract • In the past helped with keeping the body warm.

8. hair • It is produced by a hair follicle. Root is enclosed in follicle, the shaft is the part projecting from the surface. • Hair is formed by well-nourished stratum basal epithelial cells in the matrix. The farther away they get from the growing region, they become keratinized and die. • Consists of central core (medulla) surrounded by cortex layer, surrounded by a cuticle. • Cuticle provides strength, when it wears away, you get split ends.

9. Hair • Melanocytes determine hair color • Texture is determined by the shape of the hairshaft: • Oval hairshaft – smooth hair • Flat hairshaft- curly, kinky hair • Hair is all over the body with exception of palms of hands, soles of feet, lips • Hormones account for development of hairy regions such as armpits Arrectorpili- bands of smooth muscle connect to hair follicle and dermal tissue, when muscles contract they form “goose bumps”

10. Nails • Scalelike modification of epidermis- mostly nonliving material • They have a free edge, a body and a root, border is overlapped by skin folds. • Nails are transparent and nearly colorless but look pink due to rich blood supply in the dermis • White crescent is called LUNULA

11. Skin disorders • Skin can develop more than 1000 disorders with many causes • Athlete’s foot- fungus • Boils- staph infection-bacteria • Cold Sores- virus • Contact Dermatitis- chemicals, allergy • Impetigo- staph infection, very contagious, especially common in children • Psoriasis-unknown cause- red lesions covered with dry, silvery scales, can be disfiguring.

12. Burns • Tissue damage and cell death caused by heat, electricity, UV radiation and some chemicals. • Damages due to burns: • Body loses fluids as they seep from burned surfaces, dehydration and electrolyte imbalance follows. Can lead to kidney shutdown and circulatory shock. • Infection can set in after 24 hours and your immune system is weakened because of the burn.

13. Severity of Burns • 1st Degree- only epidermis is damaged. Red and swollen. Usually not that serious. • 2nd Degree- injures epidermis and upper region of dermis. Skin is red and painful, blisters appear. Regrowth of epithelium can occur. Usually no scars. • 3rd Degree- full thickness of skin burns, appears gray-white or blackened. Nerves are destroyed. Regeneration isn’t possible, must have skin graft. • Facial burns are dangerous when Respiratory pathways are effectedsince they can swell and cause suffocation.

14. Aging Aspects • Subcutaneous tissue decreases, intolerance to cold • Skin is drier • Skin is thinner- more likely to bruise • Lost elasticity- allows bags under eyes • Hair Loss- by 50, the number of hair follicles has dropped by 1/3 and continues to decline • Male pattern baldness is an obvious baldness that increases as you age

15. Aging • Graying- amount of melanin in hair decreases or becomes entirely absent. • Causes of graying or hair loss: • Anxiety • Protein deficient diet • Chemotherapy • Radiation • Excessive Vitamin A • Fungal disorders This is usually not permanent when it comes to hair loss.