1. The Integumentary System Chapter 6

2. Organs are two or more tissues which together perform a specialized function. Epithelial membranes are thin structures that usually contain both epithelial and connective tissue.

3. Three types of epithelial membranes Serous Membranes –Line cavities and cover organs –Simple squamous epi. over loose connective tissue –Parietal and visceral portions –Secrete a serous (watery) fluid for lubrication

4. Mucous membranes –Line cavities that open to the exterior –Layer of epithelium over connective tissue; epithelium varies with location –Tight junctions and goblet cells Cutaneous membrane is the skin –the major organ of the integumentary system

5. Integumentary system is the skin and the organs derived from it (hair, glands, nails) One of the largest organs –2 square meters; 10-11 lbs. –Largest sense organ in the body The study of the skin is Dermatology

6. Functions: 1. Regulation of body temperature –Cellular metabolism produces heat as a waste product. –High temperature Dilate surface blood vessels Sweating –Low temperature Surface vessels constrict shivering

8. 2. Protection physical abrasion dehydration ultraviolet radiation 3. Sensation touch vibration pain temperature

9. 4. Excretion 5. Immunity/ Resistance 6. Blood Reservoir 8-10 % in a resting adult 7. Synthesis of vitamin D uv light aids absorption of calcium

10. Anatomy Epidermis Skin Dermis Subcutaneous layer or hypodermis

16. Epidermis Stratum basale (stratum germinativum) –Single layer of cuboidal to columnar cells –Stem cells that produce keratinocytes –Melanocytes - # the same for all races Melanin produced in a melanosome

17. Stratum spinosum (thorn-like, prickly) –8-10 layers attached by desmosomes –See spines when cell is stained for microscopy –Keratinocytes take in melanin by cytocrine secretion

20. Stratum granulosum –3-5 layers –Keratinization begins here –Keratohyalin found in granules –Cells beginning to die

21. Stratum lucidum (lucid = clear) –More apparent in thick skin –3-5 layers of clear cells –Eleidin Stratum corneum (corneum means horny) –Dead, flat cells full of keratin –Keratin is waterproof –Cells are shed Basal cell to surface – about 2-4 weeks

22. Dermis Connective tissue layer Collagen and elastic fibers, nerves, blood vessels, muscle fibers, adipose cells, hair follicles and glands. Papillary layer –1/5 of dermis – loose areolar connective tissue –Highly vascular –Dermal papillae - fingerprints

23. Reticular (net) layer –Dense irregular connective tissue –Sebaceous (oil) glands –Hair follicles –Ducts of sudoriferous (sweat) glands –Striae or stretch marks –Meissner’s corpuscles and Pacinian corpuscles

24. Hypodermis Attaches the reticular layer to the underlying organs Loose connective tissue and adipose tissue Major blood vessels – rete cutaneum

25. Accessory organs or epidermal derivatives Hairs –Epidermal growths that function in protection –Shaft, root, and folllicle –Sebaceous glands, arrector pili muscle, and hair root plexus (touch) –Hair growth and replacement have a cyclical pattern –‘male-pattern’ baldness

29. Nails Plates of highly packed, keratinized cells Protection, scratching, & manipulation Formed by cells in nail bed called the matrix ( in area of lunula) 1 mm / week Eponychium - cuticle

32. Skin Glands Sebaceous (oil) glands –Usually connected to hair follicles –Holocrine glands –Fats, cholesterol, proteins, salts, and cell debris –Moistens hair and waterproofs skin

33. Sweat (sudoriferous) glands –Eccrine sweat glands Merocrine glands Water, salt, wastes Function is to cool the body (also nervous) –Apocrine sweat glands Larger, merocrine glands Associated with hair follicles More viscous – fatty acids and proteins Odor occurs when broken down by bacteria

34. Ceruminous glands –Modified sudoriferous glands –Secrete cerumen (ear wax) Mammary glands –Secrete milk

37. Skin color Genetic factors –Same number of melanocytes –Albinism Environmental factors –Uv light or x-rays

39. Physiological factors –Amount of blood –Amount of oxygen Cyanosis Carotene accumulation Jaundice – liver disorder

40. Wound healing Inflammation –Blood vessels dilate and become permeable Heat, redness, swelling and pain Shallow cuts –Epithelial cells migrate –Contact inhibition

42. Deeper wounds Inflammatory phase –Fibrin forms clot Migratory phase –Fibroblasts make granulation tissue Proliferative phase Maturation phase Scars – hypertrophic scar –keloid

47. Burns First degree or partial thickness burn –Only epidermis is damaged –Erythema, mild edema, surface layer shed –Healing – a few days to two weeks –No scarring

48. Second degree- deep partial-layer burn –Destroys epidermis –Blisters form –Healing depends on survival of accessory organs –No scars unless infected

49. Third degree or full-thickness burn –Destroys epidermis, dermis and accessory organs of the skin –Healing occurs from margins inward –Skin grafting may be needed Autograft Homograft Rule of Nines