Integumentary System

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Instructor: Terry E. Jones

A. Protects deeper tissues from: 1. Mechanical damage - (bumps) 2. Chemical damage - (acids/bases) 3. Bacterial damage

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4. Ultraviolet radiation - (damaging effects of sunlight) 5. Thermal (heat or cold) damage 6. Desiccation (drying out)

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B. Aids in body heat loss or heat retention (controlled by the

nervous system)C. Aids in excretion of urea and uric

acidD. Synthesizes vitamin D

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A. Epidermis Layer (5 sub-layers) 1. Has no vascular tissue 2. Gets nourishment by diffusion 3. Most cells are filled with keratin fibers – makes the skin tough

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4. Deepest layer is the stratum basale a. Produce millions of cells that push upward b. Also called stratum germinativum

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5. As cells move upward, they become filled with keratin 6. Next layer –stratum spinosum 7. Followed by the stratum granulosum

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8. Next layer is clear – stratum lucidum. Found only on palms and soles of feet. 9. Outer layer is the stratum corneum.

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10. Outer layer dead cells. Our skin is new every 25-45 days. 11. Melanocytes are found in the basale layer and produce melanin. Basale cells engulf melanin to protect DNA from UV rays.

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B. Dermis Layer (2 sub-layers) 1. Underlies the epidermis. 2. Top Layer- papillary layer a. Uneven with finger like projections into the epidermis b. Have capillaries to nourish the lower epidermis

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c. Projections on fingers form the fingerprints for gripping things d. Some projections are touch and pain sensors.

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e. Lots of tough collagen fibers f. Phagocytes cruise around eating bacteria that get through the epidermis

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C. Skin Appendages 1. Sebaceous oil glands a. Ducts empty oil into hair follicle b. Oil kills bacteria and keeps hair from getting brittle

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2. Exocrine Sweat Glands a. Ducts sweat into pores b. Sweat contains water, salts, vitamin C, ammonia, uric acid and lactic acid that attracts mosquitos

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3. Apocrine Sweat Glands a. Develop at puberty in axillary and genital regions b. Sweat contains fats and proteins that bacteria love – body odor made by bacteria

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4. Hair and Hair Follicles a. Follicle-end in the skin b. Shaft – what we see c. Basale cells push upward forcing the dead cells out which now are mostly keratin

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d. Each hair has a tiny muscle that moves it called the arrector pili e. The little muscles cause goose bumps when its cold

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5. Nails a. Cells push outward from the basale layer and become keratinized b. Nail grows from the matrix end (little white crescent) c. Most of the nail are dead cells turned to keratin

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A. Infections and Allergies 1. Athlete’s Foot- fungus disease 2. Boils and Carbuncles a. Neck area b. Caused by bacteria infection

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3. Cold Sores –caused by a virus infecting mouth area and lips 4. Contact Dermatitis –caused by exposure to a chemical such as poison ivy 5. Impetigo-Bacterial infection causing watery blisters on skin

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6. Psoriasis – dry, scaly skin for which the cause is not known. May be genetic or stress related.

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B. Burns 1. Causes –Cell Death a. Intense heat b. UV radiation – sunburn c. Electrical d. Chemicals- Acids

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2. First Degree Burn a. Involves the epidermis only b. Causes redness c. Recovery occurs

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3. Second Degree Burn a. Involves the epidermis and part of the dermis b. Redness and blistering c. Recovery is good, usually no scarring

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4. Third Degree Burn a. The dermis layer is completely dead b. Whitish or black, tissue exposed c. Recovery long and serious, only a

skin graft can replace the dead skin

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C. Cancer 1. Basale Cell Carcinoma a. Least malignant b. Slow growing c. 99 % curable

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2. Squamous Cell Carcinoma a. Occurs in the stratum spinosum b. Major cause is UV exposure c. Can metastasize d. Successfully treated if caught early

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3. Malignant Melanoma a. Occurs in the melanocytes b. About 5 % of Skin cancers c. Can metastasize d. 50 % survival rate with treatment

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