1. Biology 322 Human Anatomy I Integument

2. Functions of Integumentary System (skin & its products) Barrier to keep water and solutes in Barrier to keep bacterial, dirt, etc. out Protection against abrasion Contains sensory receptors for touch, temperature, pressure, pain, etc. Temperature regulation via hair, sweat, & amount of blood flow Blood reservoir Synthesis of vitamin D Excretion

3. Three Layers of skin:

4. Epidermis: Avascular. Depends on blood vessels in underlying dermis for its nutrition

5. = Single row of dividing cells (Epidermis) = Three or four layers of cells; Some cell division = Three or four layers of cells; Actively synthesizing protein keratin = One or two layers of dying cells Not present in thin skin = Many layers of flat, dead, scale-like cells full of keratin (Connective tissue)

6. Primary cell type in epidermis = which produce large amounts of protein Other cell types:

7. Two related forms of melanin: Black or brown Responsible for dark skin or hair Red or pink Responsible for pink skin (lips, nipples, glans of clitoris or penis, freckles) and red hair Both synthesized

9. Keratinocytes move from stratum basale to stratum corneum, dying as they do so. Average = 5 - 6 wks - Keratinocytes in stratum basale (& stratum spinosum) lie along basement membrane; divide by mitosis - Older cells die but remain attached to each other - Older ones pushed toward surface by newer cells - Cells eventually shed from stratum corneum - Keratinocytes synthesize large amounts of keratin and flatten out as they move toward surface - Melanocytes transfer melanin to keratinocytes (Epidermis)

10. Dermis : Two Layers:

11. Dermis = Dense irregular connective tissue. Thus: Cells = Fibers =

12. Dermis: Contains many types of sensory receptors for touch, pressure, vibration, pain, temperature, etc. Some = simple nerve endings Others = complex structures with multiple cell types

13. Appendages of the skin All begin as epidermis of embryo; grow down into dermis

14. Hair - Distribuled over all skin except: palms of hands soles of feet nipples glans of penis & clitoris minor labia - Formed in follicles located deep in dermis - Consists of layers of dead, highly keratinized keratinocytes

18. Black or brown Blond Red Gray or White

20. Each hair is associated with:

21. Sweat Glands

22. Two specially modified sweat glands :

23. Sebaceous (oil) glands: - Branched tubular glands - Duct opens into opening of hair follicle - Secretes sebum, consisting of lipids, proteins, ions, carbohydrates,

24. Nails: - Tips of fingers and toes - Thick layer of densely packed keratinocytes - Produced by Deeper layers of epidermis = Average growth: 0.5 mm per week

25. Carcinomas (cancers) of the skin: Basal Cell Carcinoma: Keratinocytes of stratum basale proliferate, invade dermis Relatively low malignancy Squamous Cell Carcinoma: Keratinocytes of epidermis proliferate. May invade dermis Moderate malignancy Malignant Melanoma: Melanocytes of epidermis proliferate, invade dermis Highly malignant