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.
c. Ceruminous glands - modified apocrine glands in the ear canal - secrete “earwax” - deters/traps foreign substances
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
* Blocked sebaceous gland = whitehead * Acne = inflammation of the sebaceous glands…caused by a bacterial infection. * Seborrhea = overactive Sebaceous glands in infants: Cradle Cap
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
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
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
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
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
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!
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 http://www.dermatology.ca/english/news/july-2005_e.html