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Chapter 5

Unit II: Organization Integumentary System Part II. Chapter 5. Skin Organs Cutaneous Glands. Five types of Exocrine glands: Merocrine sweat glands Apocrine sweat glands Sebaceous glands Ceruminous glands Mammary glands. Skin Organs Cutaneous Glands.

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Chapter 5

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  1. Unit II: Organization Integumentary SystemPart II Chapter 5

  2. Skin OrgansCutaneous Glands • Five types of Exocrine glands: • Merocrine sweat glands • Apocrine sweat glands • Sebaceous glands • Ceruminous glands • Mammary glands

  3. Skin Organs Cutaneous Glands Sweat Glands (sudoriferous glands) • Plasma and waste products • 500 ml of insensible perspiration/day • diaphoresis – visible sweating (1L/hr) • Merocrine glands is a simple tubular gland • millions of them help cool the body • Apocrine glands produce sweat containing fatty acids • found only near hair follicles after puberty • Scent glands that respond to stress and sex

  4. Skin Organs Cutaneous Glands Sebaceous Glands Sebaceous gland Lumen (hair removed) Wall of hair follicle • Flask-shaped gland • opens into hair follicle • Some onto skin surface (pimples) • Oily secretion called sebum • contains broken-down cells, fat, wax • lanolin in skin creams is sheep sebum Basal lamina Discharge of sebum Lumen Breakdown of cell membranes Mitosis and growth Germinative cells

  5. Skin Organs Cutaneous Glands Ceruminous Glands • Found only in external ear canal • Produce cerumen • Functions of earwax: • waterproof • keeps eardrum flexible • bitterness repel mites and other pests

  6. Skin Organs Cutaneous Glands Mammary Glands • Developed glands found only during lactation and pregnancy • modified apocrine sweat gland • Produce milk (lactate) • All individuals have undeveloped glands • Must have high levels of estrogen to develop • Mammary ridges or milk lines • 2 rows of mammary glands • Polythelia – additional nipples • may develop along milk line

  7. Skin Color(Pigmentation) • Melanin = yellow, brown, and black hues • All individuals have same number of cells • Cells stimulated by UV radiation to become more active • Hemoglobin = red • Carotene = yellow, orange from diet • concentrates in stratum corneum and hypodermis

  8. Skin ColorAbnormalities • Cyanosis = blueness from deficiency of oxygen in the circulating blood (cold weather) • Erythema = redness due to dilated cutaneous vessels (anger, sunburn, embarrassment) • Jaundice = yellowing of skin and whites of the eyes due to excess bilirubin in blood (liver malfunction)

  9. Skin Color Abnormalities • Pallor = pale color from lack of blood flow, dermal collagen shows thru (low blood pressure, emotional stress) • Albinism = a genetic lack of melanin • Hematoma = a bruise (visible clotted blood)

  10. Skin Markings • Friction ridges • formed during fetal development • Unique pattern even for identical twins • Flexion lines • Formed where skin folds during flexion of joint • Freckles and moles = • Aggregation of melanocytes • freckles are flat; moles are elevated • Hemangiomas • discolored skin caused by benign tumors of dermal blood capillaries

  11. Tissue Repair • Regeneration • replacement of damaged cells with original cells • Restores original function • Epidermis and liver • Fibrosis • replacement of damaged cells with scar tissue (collagen) • Function is not restored • healing muscle injuries, scarring of lung tissue in TB or healing of severe cuts and burns of the skin (dermis)

  12. Wound Healing Initial Injury Immediately after the injury, mast cells in the region trigger an inflammatory response. Bleeding occurs at the site of injury. • Plasma carries: • Antibodies • Clotting factors • WBCs Epidermis Dermis

  13. Wound Healing After Several Hours Blood clot forms to decrease blood loss and spread of microbes Macrophages patrol the damaged area Cells of the stratum basale undergo rapid divisions to replace missing cells

  14. Wound Healing After One Week • New capillaries grow into wound • Fibroblasts deposit new collagen to replace old material • Fibroblastic phase begins in 3-4 days and lasts up to 2 weeks Fibroblasts

  15. Wound Healing After Several Weeks • Epithelial cells multiply and spread beneath scab • Scab falls off • Epithelium thickens • Connective tissue forms only scar tissue (fibrosis) • Remodeling phase may last 2 years Scar tissue

  16. Tissue Engineering • Production of tissues and organs in the lab • Build a scaffold - polyester or collagen fibers • seeded with human cells • grown in “bioreactor” to supply O2 and nutrients • Skin grafts already available • research in progress on heart valves, coronary arteries, bone, liver, tendons

  17. Skin DisordersBurns • Hot water, sunlight, radiation, electric shock or acids and bases • Leading cause of accidental deaths from: • fluid loss – loose up to 75% of plasma within a few hours • infection • Treatment – nutrition and fluid replacement, debridement and infection control

  18. Skin DisordersBurns (c) Third degree (b) Second degree (a) First degree

  19. Cancer • Tumors “swelling” • abnormal growth, cells multiply faster than they die • Benign = not cancer • slow growth, connective tissue capsule, stays local • Malignant tumor = cancer • 3 properties: • fast growing • unencapsulated • metastatic • stimulate angiogenesis

  20. Causes of Cancer • Carcinogens – environmental cancer-causing agent • chemical = cigarette tar, food preservatives, industrial chemicals • Radiation = gamma and UV • Bone density scan = 1 day of natural radiation • X-rays = 10 days • CT scans = varies (head = 8 months; abdomin/spine = 3 yrs) • Viruses = type 2 herpes simplex - uterus, hepatitis C - liver

  21. Carcinogens • Mutagens = Carcinogens – trigger gene mutations • Defenses against mutagens and tumors • Scavenger cells – remove mutagens • Peroxisomes – neutralizes free radicals • Nuclear enzymes – detect & repair damaged DNA • Natural killer cells – immune surveillance • Macrophages and monocytes secrete tumor necrosis factor

  22. Malignant Tumors • Two types of genes responsible: • Oncogenes – tells a cell to grow • sisoncogene causes excessive production of growth factors • rasoncogene codes for abnormal growth factor receptors • ¼ of human cancers • Tumor suppressor genes (TS) • Tells a cell to stop growing • damage to both removes control of cell division • ½ the cases of Leukemia, colon, lung, breast, liver, brain • Requires 5-10 mutations at different loci • Death results from metastasis not the original tumor

  23. Skin DisordersSkin Cancer • 90% of malignancies are carcinomas • High rate of mitosis • More exposed to carcinogens • All skin cancers are malignant! • Induced by UV rays of the sun • basal cell carcinoma • arises from stratum basale and invades dermis • Most common • Easiest to treat

  24. Skin Disorders Skin Cancer • squamous cell carcinoma • arises in stratum spinosum • metastasis to the lymph nodes can be lethal

  25. Skin Disorders Skin Cancer • malignant melanoma • Commonly arises from melanocytes of a preexisting mole • Least common • Most deadly • ABCDE--asymmetry, border irregular, color mixed and diameter over 6 mm, evolving

  26. Skin DisordersUVA, UVB • UVA and UVB are improperly called “tanning rays” and “burning rays” • As sale of sunscreens has risen so has skin cancer • Does not protect against skin cancer, just sunburns! • Higher incidence of basal cell carcinoma because people falsely assume they can stay out longer • Some chemicals in sunscreen may damage DNA and generate harmful free radicals when exposed to UV rays • Sunblock is better because it scatters and reflects UV rays • Learn more at http://www.ewg.org/2013sunscreen/

  27. Exam 1 • Chapters: 3, 4, 5 Spelling matters! • Fill in the blank 3x5 notecard • Multiple Choice • Matching • Short answer • True/False

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