Integumentary System

1. Integumentary System

2. (Hypodermis)

3. Integumentary System • Skin • Hair • Nails • Associated Structures (vessels, nerves, glands)

4. Membranes Epithelial membranes Cutaneous Mucous Serous Parietal vs visceral Pleura, pericardium, peritoneum

5. Integumentary System • Skin (cutaneous membrane) • Main layers – superficial to deep • Epidermis • Dermis • Hypodermis • -not always • considered • part of skin (Hypodermis)

6. Functions of Skin • Protection • Sensation • Movement without energy • Excretion • Vitamin D production – needed to absorb calcium Sun+Skin Vit D blood kidney/liver calcitriol blood regulates calcium & phosphorous • Immunity • Healing Wounds • Body temperature homeostasis • vasoconstriction & vasodilation

7. Skin Structure

8. Epidermis • Epidermis – outer layer • Keratinized stratified squamous epithelium • Avascular (hardened by keratin) • Renews itself ~ every 45 days

9. Epidermis – cell types • Keratinocytes • produce keratin – waterproofing protein • Originate in deeper layers & get pushed to surface – becomes keratin filled & dies • Connected to each other by desmosomes & tight junctions • Cell production & keratinization are accelerated in areas of friction • Callus – thickened skin

10. Epidermis – cell types • Melanocytes • Produce melanin • Prevents DNA mutation from the UV radiation • UV increases melanin production • Same number in everyone, but different amount of pigment produced • Accumulation of melanin results in freckles and moles

11. Epidermis – Skin Color • Determined by three factors: • Types of pigments present • Melanin – brown, black, or yellow pigment • Carotene • Hemoglobin • Blood circulation • Stratum corneum thickness • Orange-yellow pigment from some vegetables • Vitamin A precurser – vitamin A forms retinal which is needed for sight • Accumulates in adipose and stratum corneum cells • Red, oxygen-carrying pigment in erythrocytes • More obviously detected in fair skin

12. Skin as a Diagnostic • Skin color is influenced by emotional & disease states: You should know the states that cause these. • Cyanosis – bluish color - lack of oxygen • Erythema – redness – heat, inflammation, fever • Albinism – genetically black, but white – no melanin produced from melanocytes • Pallor – paleness – lack of blood flow • Jaundice – yellowish color – liver damage; accumulation of bilirubin • Bronzing – bronze (tan) – Addison’s disease • Hematomas – black & blue – blood under skin

13. 5 strata of the Epidermis – Deep to Superficial • Stratum basale • highly mitotic (produces new skin layer) • ~ 25% melanocytes • Stratum spinosum • Slightly mitotic • Contains Langerhan’s macrophages • Several layers of many sided cells (looks spiny) • Stratum granulosum • Also contains Langerhans cell • contains keratohyalin (helps form keratin) • Stratum lucidum • ONLY found in thicker epidermis – palms, soles, callus • Completely keratinized (and dead!) • contains closely packed, clear cells that contain gel-like substance eleiden

14. 5 strata of the Epidermis • Stratum corneum • Outermost layer • Also completely keratinized • Dead cells • Tough, waterproofing protection

16. Dermis • Middle layer of skin • Contains hair folllicles, glands, nerves, vessels, muscle • All four tissue types present • Mainly strong, flexible CT - Two layers

17. Dermis • Papillary layer • Contains Areolar CT • Dermal papillae • Indent into epidermis • forms fingerprints • Important for grip • Contains blood vessels • Meissner’s Corpuscles – nerve (touch) receptors

19. Dermis • Reticular layer • Dense irregular CT • contains blood vessels, nerves, glands, adipose • Pacinian Corpuscles – nerve endings responsible for sensitivity to deep pressure touch and high frequency vibration • Collagen – prevents overstretching and tearing of skin • Elastin – allows skin to stretch • stretch marks – dermal tears

21. Hypodermis • Not usually considered part of the skin • Also called subcutaneous layer • Site of subcutaneous injections – absorbed directly into blood stream • Anchors skin to underlying organs, shock absorption, insulation • Composed mostly of adipose tissue • Very vascular

24. Skin Appendages

25. Appendages of the Skin Hair • Minor protective functions (retain heat, decrease sunburn, eyelashes protect eyes) • Structure • shaft – projects from skin • follicle – extends into dermis • root – lies within the follicle • bulb – contains CT, vessels and nerves • sebaceous gland – lubricates hair • arrector pili muscle – attached to follicle and contracts to move hair (hair growth, goosebumps)

27. Hair

28. Appendages of the Skin • Hair Growth • influenced by: (in this order) • nutrition - main influence • hormones • blood flow • baldness ( alopecia ) • male pattern baldness - sex linked recessive genetic trait • thinning – can be caused by medications, nutrition, stress, etc. • Hair Pigment • caused by proportions of 3 melanin types • dark hair – true melanin • blonde and red – melanin with iron and sulfur • gray/white hair - melanin replaced by air bubbles in shaft

29. Appendages of the Skin Nails • Scale-like modifications of the epidermis • Heavily keratinized • Stratum basale extends beneath the nail bed to form nail matrix • Responsible for growth ( matrix region) • Lack of pigment makes them colorless • Lunula “little moon” – area of cell growth (white semicircle at base of nail) • Cuticle – area of skin that covers base of nail

30. Nail Structures

31. Sweat Glands • Eccrine glands • Widely distributed in skin: abundant on palms, soles, forehead • Sweat composition: mostly water with a slightly acidic 4-6 pH • Function: thermoregulation • Apocrine glands • Ducts empty into hair follicles • Found mainly in anogenital & axillary region • Begin to function at puberty due to hormones / pheromones • Organic contents: Fatty acids and proteins – can have a yellowish color that stains clothes • Odor is from associated bacteria • Ceruminous glands • Modified apocrine gland • Found in outer 1/3 of ear canal • Produce ear wax to trap “invaders”

33. Appendages of the Skin • Sebaceous glands • all over except palms and soles of feet • Produce oil for waterproofing • Lubricant for skin & kills bacteria • Most with ducts that empty into hair follicles • Glands are activated at puberty: stimulated by hormones • Acne – active infection of sebaceous glands

34. Burns

35. Burns • Protein denaturation and cell death caused by heat, electricity, UV radiation, or chemicals • 2 main dangers • Dehydration–Loss of fluids & Electrolytes lead to: • Renal Shutdown • Circulatory shock • Infection • Skin (mechanical) barrier lost • Immune system depresses

36. Rules of Nines • Way to determine the extent of burns • Primary importance is to estimate fluids needed for rehydration • Body is divided into 11 areas for quick estimation • Each area represents about 9%

37. Rule of nines diagram

39. Partial Thickness Burns Slide 4.27 • First-degree burns • Only epidermis is damaged • Local redness, swelling, & pain • Usually heal in 2-3 days (short time period) with NO scarring

40. Partial Thickness Burns • Second degree burns • Epidermis and dermis & structures within dermis are damaged • Appearance of blisters of any size • Skin regeneration in 3-4 weeks with some scarring • There is a danger of infection

48. Full Thickness Burns • Third-degree burns • Epidermis, Dermis, Hypodermis and all structures within are completely destroyed • Usually painless at site of burn due to destruction of sense receptors • Burn is gray-white, tan, brown, black, or deep cherry red • Surrounded by areas of 1st & 2nd degree burns that will be painful • Treatments are numerous but will involve skin grafting of some sort, fluid replacement and debridement