1. Bell Ringer:
Describe the difference between thin and thick skin.
2. What types of cells make up most of the epidermis?

2. Appendages of
the Skin

3. Sweat Glands
a. Eccrine sweat glands
- palms, soles of feet, forehead
- coiled, tubular gland
- exits out pore
b. Apocrine sweat glands
- axillary(armpit) & anogenital areas
- empty into hair follicles
- milky, yellow substance
- puberty; scent glands?

5. Sweat: Hypotonic filtrate of the blood.
99% water with salt, vitamin C, etc.
Acidic (Acid mantle)
Sweating is regulated by the sympathetic nervous system (autonomic)
Why do we sweat?…To prevent overheating of the body.

6. c. Ceruminous glands
- modified apocrine glands in
the ear canal
- secrete “earwax”
- deters/traps foreign substances

7. d. Mammary glands
- specialized sweat gland
- secrete milk

8. 2. Sebaceous (Oil) Glands
- NOT on palms and soles (WHY?)
- Secrete “sebum”
- Secreted into hair follicle or pore
- Softens and lubricates hair and skin
- Slow water loss from skin
- Bacterialcidal
- Stimulated by hormones

9. * Blocked sebaceous gland = whitehead
* Acne = inflammation of the sebaceous glands…caused by a bacterial infection.
* Seborrhea = overactive
Sebaceous glands in infants: Cradle Cap

11. Hair and Hair Follicles
1. Functions of hair
- sense insects on skin
- protects head against trauma, heat loss, and sunlight
- eyelashes shield and protect eyes
- nose hairs filter particles

12. 2. Structure of Hair
a. Hair (pili): Nonliving; keratinized
Hard (not soft) keratin
Shaft and root
b. Cuticle: Outermost layer of hair shaft (single cell layer)
Conditioners smooth out this rough surface

17. Hair pigment is made by melanocytes at the base of the hair follicle and transferred to cortical cells.
Gray hair = decreased melanin production (delayed-reaction genes)
- Cortex and Medulla

18. Miscellaneous Hair Info…
- Sensory nerves wrap around each hair bulb…bending hair stimulates these.
- The hair shaft is nonliving (protein).
- Arrector pili = muscle that pulls hair in upright position (goosebumps and erect hair…why?)
- 90 scalp hairs lost daily
- Follicles of eyebrow hair only active 3- 4 months

19. Nails!
- scale-like modification of the epidermis, made of keratin
- forms a clear protective covering on dorsal surface of fingers and toes
- hooves/claws
- protection/defense
- nail matrix = nail growth
- lunula - “little moon”
- cuticle = nail fold

22. Functions of the Integumentary System
Protection
Body temperature regulation
Sensation
Vitamin D production (for Ca++ metabolism)
(UVB + 7-dehydrocholesterol = Vit. D)
(Ca++ can not be absorbed from the digestive tract without vitamin D…sometimes products (like milk) are fortified with vitamin D.)
Eat fish, egg yolk = good Vit. D sources!

23. Vitamin D…more! (30 minutes of sun/day b/w 11-4)
- SPF > 8 prevents Vitamin D synthesis
- Need more Vitamin D as you get older
“Only brief sun exposure to either the back of the hands, arms, or face, two to three times a week from May to September, is required to maintain sufficient vitamin D levels through production of vitamin D in the skin…Regarding the use of sun beds and claims that exposure to these sources of ultraviolet radiation promotes vitamin D production, the major ultraviolet component emitted by the light bulbs used in tanning parlours is ultraviolet A which has no effect on Vitamin D production. Many lamps also emit a smaller amount of ultraviolet B.”
~ Dr. Cheryl Rosen, national director of the Canadian Dermatology Association's National Sun Awareness Program

24. Rickets: Vitamin D deficiency, malnutrition

25. Skin Cancer
- Squamous cell carcinoma
- Basal cell carcinoma
- Melanoma
Risk factors and Prevention?
Take the Skin Quiz