Integumentary System

1. Integumentary System

3. Integumentary System • 7% of total body weight • Components: • Cutaneous Membrane • Epidermis • Dermis • Subcutaneous layer • 2. Accessory structures • Hair • Nails • Glands • Sensory receptors

4. Functions • 1. protection, cushion, insulate • 2. excretion of salts, water, wastes • 3. maintenance of temp. • 4. synthesis of Vitamin D3 • 5. storage of nutrients • 6. detection of touch, pressure, pain, and temperature

5. Epidermis • Stratified squamous Epithelium • 4-5 layers thick • .08-.5 mm thick

6. Stratum Germinativum (Basale) • Innermost layer (deepest) • 3-5 cells thick • Contains Merkel cells- sensory for touch • Contains melanocytes (pigment cells) 10-25% • Cells reproduce in this layer (mitosis)

8. Stratum Spinosum (spiny layer) • 8-10 cells thick • Contains Langerhans cells which defend against microorganisms and some skin cancers • Mitosis occurs, but less than in Basale layer

10. Stratum Granulosum (grainy) • 3-5 cells in thickness • Most cells stop dividing in this layer • Produce keratohyalin to start the hardening/waterproofing of cells (keratinization)

12. ONLY in THICK skin (palms & soles) 3-5 cells in thickness Flattened cells with eleidin Stratum Lucidum

13. Stratum Corneum • Outermost layer • Cell membrane thicken; less permeable • Cells die, dehydrate, and keratinize • Keratinization make skin water resistant, less permeable • Average person sheds 40 lbs (18kg) in a lifetime

15. Skin Color • Due to pigments and blood supply • 1. Pigments • Carotene- orange/yellow • Can be converted into Vitamin A • Obtained from plant foods (carrot/tomato) • Melanin- brown, yellow/brown, or black • Produced by melanocytes • Protects cells from UV rays • UV exposure = melanocyte activity = color (tan) • ≈ 1000 melanocytes/ mm²

16. Circulation blood in dermis gives skin a reddish tint due to the hemoglobin Hematoma = bruise Poor 02 = bluish tint (cyanosis) Decubitis Ulcers (bed sores) are caused by lack of blood supply to an area Skin Color

17. Vitamin D • UV exposure causes epidermal cells to produce Vitamin D, a vital hormone, which ensures proper bone growth and development • Vitamin D enables calcium absorption

18. Dermis • Binds epidermis to underlying tissue • Contains blood vessels, neurons, hair follicles, sweat glands, fibroblast, macrophages, and white blood cells • Strong flexible connective tissue • 2 layers

19. Dermis • 1. Papillary layer ( superficial 20% of Dermis) • Loose connective tissue (areolar) • Contains dermal papillae • Fingerlike pegs form fingerprints, palmprints, footprints

20. Dermis • 2. Reticular layer (80% of Dermis) • Dense c.t./collagen and elastic fibers • collagen fibers give tensile strength/resilience • Elastic fibers provide stretch/recoil properties • Separations or less-dense regions between the collagen bundles form the lines of cleavage or tension lines of the skin—important to surgeons • Flexure lines-deep creases where dermis attaches tightly to underlying structures • Site of tatoos

21. Subcutaneous layer(hypodermis) (superficial fascia) • Deep to the skin • Loose c.t. (areolar) and adipose • Stabilize the position of the skin/anchors to underlying structures (mostly muscle), but allows slide • Contains blood vessels • No organs • Insulator • Thickens with weight gain • ♀ Breast/Thighs • ♂ anterior abdomen “beer belly”

22. Present on all skin surfaces except palms, soles, lips , some external reproductive organs Develops from hair follicle (epidermal cells) Sense things that lightly touch our skin, protect scalp, shield eyes, filter air we breathe Hair

23. Grows 2-6 yrs, rests 2 months, then falls out Cells divide at the base and push others up which keratinize (hard) and die Root: embedded Shaft: above skin surface Three layers: medulla Cortex cuticle Hair

24. Color is determined by two types of melanin and amount Arrector pili muscle (smooth) is attached to each follicle; when contracts = hair is on end Vellus- fine “peach fuzz” (women/children) Terminal – long, dark, typical (scalp/puberty) Average growth of 2mm per/week hair

25. nails • Composed of keratinized stratified squamous epithelium • Free edge, body, root • Cell division occurs in nail root (matrix) under cuticle; extends out in half moon shape (lunula) • As it develops, slides forward over a layer of epithelium (nail bed)

26. A. Sebaceous Usually around hair follicles Produce oily secretion (sebum) Keeps hair and nails smooth and soft Stimulated by hormones, especially androgens Glands

27. Sweat • 99% water, some salts, and traces of metabolic wastes • Normally produce 500ml per day and up to 12 L on hot days and during vigorous exercise

28. B. Sudoriferous (sweat) Originate deep in dermis or subcutaneous layer Ball shaped coil with tube leading to surface glands

29. Some sweat glands (eccrine) respond to high body temperature and are scattered all over the body Most abundant on palms, soles, forehead, back, neck Watery Sudoriferous (sweat)

30. Some sweat glands (apocrine) respond to stress and are located in the axillary and groin regions; functional after puberty Thick, sticky, odorous Sudoriferous (sweat)

31. There are two types of sweat glands that are modified: • 1. Ceruminous glands are in the external ear canal and secrete cerumen (ear wax) • 2. Mammary glands which are in the breasts and secrete milk

32. Regulation of Body temp. • Excessive heat production • Blood vessels in dermis dialate • Eccrine glands activated-sweat heat lost • Respiration may increase; heat lost thru exhalation • Heart may beat faster; more blood moves into the skin

33. Excessive heat loss • Blood vessels in dermis constrict; decreases blood flow to skin; conserves heat • Sweat glands inactive • Nerves may stimulate muscles to contract rhythmically – shiver; generates heat.

36. burns • A burn is tissue damage inflicted by heat, electricity, radiation, extreme friction, or certain harmful chemicals • The immediate threat to life from serious burns is a catastrophic loss of body fluids

37. Fluid seeps from the burned surfaces • The body quickly loses water and salts • Dehydration leads to fatal circulatory shock • After the initial crisis has passed, infection becomes the main threat.

38. Burns are classified by their severity (depth) as first, second, or third degree burns

39. First degree burns • Only the epidermis is damaged • Redness, swelling, and pain • Heal in a few days • Ex. sunburn

40. Second degree burns • Injury to the epidermis and the upper part of the dermis • Redness, swelling, blisters, and pain • Skin regenerates in 3-4 weeks w/ little or no scarring

41. Third degree burns • Consume the entire thickness of the skin • White, red, or blackened • The skin might eventually regenerate, but it is impossible to wait for this because of fluid loss and infection • Skin from other parts of the patients body must be grafted

42. Burns are considered critical if any of the following conditions exist: • 1. Over 10% of the body has third-degree burns • 2. 25% of the body has second-degree burns • 3. There are third degree burns on the face, hands, or feet.

43. Body surface divided into 11 regions, each accounting for 9% (or a multiple of 9%) of total body area Rule of nines

45. Skin cancer • Skin cancer is the most common type of cancer, w/ about 1 million new cases appearing each year in the U.S. • Most important risk factor: overexposure to the UV rays in sunlight

46. Basal cell carcinoma • Least malignant • Most common • Cells of the stratum basale proliferate—invade the dermis and hypodermis causing tissue erosions • Dome shaped, shiny nodules • Develop a central ulcer and a “pearly” beaded edge • Grows slowly, metastasis seldom occurs

47. Squamous Cell Carcinoma • Keratinocytes of the stratum spinosum • Scaly, irregular, reddened papule • Grows rapidly • Will metastasize if not removed • If treated early, chance of complete cure is good. • Radiation therapy, surgery, or skin creams w/ anticancer drugs

48. Melanoma • Cancer of melanocytes • Most dangerous, 1 of every 20 skin cancers • Melanoma can originate wherever there is pigment, often from existing moles • Appears as an expanding dark patch • Metastasize rapidly • Key—early detection • Resistant to chemo and current immunotherapy treatment, vaccines being tested.

49. ABCD (E) rule • A: asymmetry: the two halves of the spot or mole don’t match • B: Border irregularity: the borders have indentions and notches • C: Color: the pigment contains several colors, blacks, browns, tans, blues, reds • D: Diameter: larger than 6 mm (pencil eraser) • E: Elevation: above the skin surface