The Integumentary System

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