1. The Integumentary System Chapter 11 pg 204-205

2. The Integumentary System Composed of the skin, sweat and oil glands, hair, and nails Accounts for 7% of the body’s weight. Major role is protection from disease causing critters and dehydration. Plays large role in homeostatsis = maintaining constant internal environment in the body Creates vitamins (D), has lots of sensory receptors 3 distinct layers Epidermis, Dermis, and hypodermis

4. Regions of Skin Epidermis Outermost layer Composed mostly of stratified squamous epithelium Base cells get squashed as push to surface, where they produce keratin protein and harden (armor) Dandruff = accelerated keratinization (3-4X too fast) Fingerprints = patterns in the epidermis Contains 4 distinct cell types and 4 to 5 distinct layers.

5. Cell Types of the Epidermis Melanocytes—synthesize melanin. Located at the deepest layer of the epidermis. The melanin is transferred to the keratocytes. Protects against UV damage.

7. The Dermis Made mostly of connective tissue. The hide of the human body. Richly innervated and vascularized. Contains the hair follicles, sweat glands, oil glands, lymphatic vessels, and many sensory receptors.

9. The Dermis Consists of 2 layers. –Papillary layer—areolar connective tissue, heavily vascularized. Contains the dermal papillae, capillary loops, and Meissner’s corpuscles. –In some areas these lie on top of the dermal ridges. Cause the epidermal ridges that cause fingerprints. –Reticular layer—dense irregular connective tissue. Importance of this structure. Flexure lines.

10. The Dermis Skin color—determined by melanin, carotene, and hemoglobin. Why do different people have different skin colors? Freckles & moles Role of melanin Role and source of carotenes & hemoglobins.

11. The Dermis Photosensitivity Erythema Pallor—paleness Jaundice Bronzing Bruises & hematomas

12. Skin Appendages Whiteheads Blackheads Acne—staphylococcus Hair—covers the entire body except for the palms, soles, lips, nipples, and parts of the genitalia. Functions of hair. Mostly dead keratinized cells.

13. Nails Modification of the epidermis Composed of keratin protein (like hair). Composed of a free edge, body, and a root. Nail root — epidermis gives rise to cells Lunula – dense collection of cells (a white moon) Nail Body – cells of the nail

16. Functions of the Integument Chemical barriers Biological Barriers Physical barrier

17. Functions of the Integument Temperature Regulation –Sweat glands Sensation –Many nerves present Metabolic Functions –Vitamin D synthesis Blood Reservoir –Shunts more blood into the circulation when needed. Excretion

18. Hair Follicles Located in the dermis Shaft extends out of epidermis Papilli muscles hold shaft erect giving goose bumps Root of hair = epithelial cells Epidermal cells die and keratinize, becoming hair

21. Oil Glands = Sebaceous Glands - meant to lubricate growing hair with “sebum” - designed to keep skin supple - white heads and blackheads form when glands do not discharge to skin's surface - Acne = inflammaton of sebaceous glands influenced by hormones

22. Sweat Glands - Some open to hair follicles - Most open to epidermis - Cooling system --> homeostasis