1. Appendages of the skin Sweat glands, oil glands, nails and hair follicles

2. Sweat (Sudoriferous) Glands Distributed over the entire body except the nipples and parts of the external genitalia More than 2.5 million per person 2 types: eccrine and apocrine

3. Eccrine Sweat Glands Far more numerous and abundant on palms, soles of the feet and forehead.

4. Sweat 99% water Also contains salts vitamin C antibodies traces of metabolic wastes (urea) Lactic acid (chemical that attracts mosquitoes) Ingested drugs may be secreted by this route

5. Role of Eccrine Sweat Prevents overheating Heat induced: begins at forehead and spreads inferiorly “Cold sweats” :due to fright, nervousness or embarrassment) begins on the palms, soles and axillae

6. Apocrine Sweat Glands The stinky sweat Axillary and anogenital areas Ducts empty into hair follicles Sometimes has a milky or yellowish color (pit stains) Odor comes from bacteria feeding on it (B.O.)

7. Role of Apocrine Sweat Begins functioning at puberty No role in thermoregulation Activated during pain and stress Activity also increased during sexual foreplay  thought to be analogous to sex pheromones in animals

8. Other apocrine glands Ceruminous glands Line the external ear canal Creates earwax Thought to deter insects Mammary glands Secrete milk

9. Oil (Sebaceous) Glands Found all over the body EXCEPT palms and soles Secrete sebum (accumulated lipids) Softens/lubricates hair & skin Slows water loss from skin Acts as a bactericidal Can result in acne: pimples, whiteheads and blackheads

11. Nails Scale-like modification of the epidermis Used as tools to pick up small objects and scratch Contains hard keratin

12. Hair and Hair Follicles Used to sense insects before they sting/bite Protects against trauma, heat loss and sunburn (scalp) Eyelashes shield eyes Nose hairs filter the air we breathe Eyebrows help to catch sweat/debris that may enter the eye

13. Hair Also called pili: consist of dead, keratinized cells Area that projects from the skin is the shaft and the root is embedded in the dermis

14. Hair Structure 3 layers: Medulla: central core Cortex: surrounds the medulla Cuticle: form a single layer that overlap one another Prevents matting Wears most easily = split ends

15. Hair Color Pigments made by melanocytes at the base of hair follicle are transferred to the cortex Various proportions of melanin contribute Red hair: iron containing pigment trichosiderin Gray hair: lack of melanin and replacement by air bubbles