CP PHYSIOLOGY: SKIN & THE INTEGUMENTARY SYSTEM

1. CP PHYSIOLOGY:SKIN & THE INTEGUMENTARY SYSTEM

2. 4 TYPES OF MEMBRANES 1) serous membranes: • line body cavities that don’t open to the outside • location: thorax, abdomen & the organs within • made of: simple squamous epithelium + loose areolar CT

3. 4 TYPES OF MEMBRANES 2) mucous membranes: • line cavities & tubes that open to the outside • location: oral & nasal cavities, tubes of the digestive, respiratory, urinary, & reproductive systems • made of: epithelium w/ goblet cells + loose areolar CT • secrete: mucus

4. 4 TYPES OF MEMBRANES 3) synovial membranes • location: the inner linings of synovial joint cavities • made of: dense CT + loose areolar CT + adipose tissue • secrete: synovial fluid to lubricate joints

5. 4 TYPES OF MEMBRANES 4) cutaneous membranes: • skin

6. INTRODUCTION • integumentary system = skin + accessory organs • hyperhidrosis = a condition of profuse, uncontrollable, unpredictable sweating

7. SKIN & ITS TISSUES • skin is a large organ vital to maintaining homeostasis

8. Skin stats: • Surface area = 1.2 to 2.2 square meters • Weight = 9 to 11 pounds • Accounts for 7% of an adult’s total body weight • 1.5 to 4 mm thick in various parts of the body • Integument = “covering”

9. functions of skin: • Protection: chemical, physical, biological • regulates body temperature • Insulation + fat storage • prevents water loss from deeper tissues

10. functions of skin: • houses sensory receptors sensitive to pain, temperature, touch, pressure • makes biochemicals such as vitamin D • excretes some waste • Blood reservoir – has an extensive vascular supply

11. 2 layers of skin: • epidermis = outer layer made of stratified squamous epithelium

12. 2 layers of skin: • dermis = thicker inner layer made of connective & epithelial tissue, smooth muscle, nervous tissue, blood

13. 2 layers of skin: • the 2 layers are separated by the basement membrane (areolar c.t.)

14. a subcutaneous layer (hypodermis, sub Q) made of loose CT & adipose tissue binds the skin to the organs under it

16. EPIDERMIS: • 4 layers: • stratum basale= base layer • stratum spinosum= prickly layer • stratum granulosum= granular layer • stratum corneum = horny layer + • stratum lucidum = clear layer • can only be found on palms & soles / thick skin

17. EPIDERMIS: • the deepest layer of the epidermis, the stratum basale, contains cells that divide

18. EPIDERMIS: • epidermal cells undergo keratinization as they mature & are pushed toward the surface • the outermost layer, the stratum corneum, is made of dead epidermal cells which are eventually shed • 40 pounds in an average lifetime! • Cornu = horn • Totally new epidermis in 25-45 days!

20. EPIDERMIS: • the rate of cell division increases where skin is rubbed off regularly forming calluses & corns • the epidermis protects underlying tissues against water loss, injury, & the effects of harmful chemicals

21. EPIDERMIS: • melanin protects cells from the effects of UV light • melanocytes (cells that make melanin) transfer melanin to epidermal cells which determines skin color

23. SKIN COLOR: • genetically determined • varies based on the kind & amount of melanin produced, since all people have about the same number of melanocytes

24. SKIN COLOR: • influenced by environment (exposure to sun) • influenced by physiological factors (blood color, diet, chemicals such as bilirubin)

26. DERMIS: • Composed of strong, flexible c.t. • Corresponds to animal hides used to make leather • dermis binds the epidermis to underlying tissues

27. DERMIS: • fingerprints result from epidermal ridges projecting inward & dermal papillae projecting upward • genetically determined • increase friction & enhance gripping ability

28. DERMIS: • dermal blood vessels supply nutrients to all skin cells & help regulate body temperature (vasoconstriction, vasodilation) • the dermis also contains hair follicles, sweat glands, & sebaceous (oil) glands

29. DERMIS: • nerve fibers are scattered throughout the dermis • some carry impulses to muscles & glands • some are associated with sensory receptors in the skin, & they carry impulses to the brain & spinal cord

30. DERMIS:

31. SUBCUTANEOUS LAYER: • made of loose CT + adipose tissues • it helps supply the skin with blood • the adipose tissue helps conserve body heat

32. ACCESSORY ORGANS OF THE SKIN • hair • hairs develop in the follicles • new cells push older cells closer to the surface where they become keratinized & die • hair color is genetically determined • an arrector pili muscle attaches to each hair follicle & this pulls the hair erect when stimulated = goose bumps

33. Functions of hair • To sense insects on skin • Guards against physical trauma, heat loss, sunlight • Eyelashes shield eyes • nose hairs filter large particles from air

34. ACCESSORY ORGANS OF THE SKIN • sebaceous glands • glands that secrete sebum = a mix of oil & cellular debris • sebum keeps skin & hair soft, pliable, & waterproof • acts as a bactericide • function begins at puberty

35. ACCESSORY ORGANS OF THE SKIN • sweat glands = sudoriferous glands • exocrine glands which consist of a coiled tube • eccrine sweat glands respond to elevated body temp. • apocrine sweat glands respond to pain or emotional stress, function begins at puberty

36. Apocrine sweat gland eccrine sweat gland * Nervous, anxious * hot

37. ACCESSORY ORGANS OF THE SKIN • 2.5 million, most in palms, soles, forehead • modified sweat glands include mammary glands & ceruminous glands in the outer ear canal

38. ACCESSORY ORGANS OF THE SKIN • nails • protective coverings for fingers & toes • each nail consists of a nail bed + nail plate • the white moon-shaped lunula at the base of the nail plate is the area where cells are most actively dividing • again, cells become keratinized & die as they age

39. REGULATION OF BODY TEMPERATURE • vital because heat affects the rate of metabolic reactions • heat is a product of metabolism • skin constantly loses heat to the air

40. REGULATION OF BODY TEMPERATURE • If temp is too high: • dermal blood vessels dilate • sweat glands secrete sweat • if temp is too low: • dermal blood vessels constrict • sweat glands deactivate • skeletal muscles contract involuntarily = shivering

41. HEALING OF WOUNDS • skin injuries trigger inflammation (red, warm, swollen, tender) • dividing epithelial cells fill in shallow cuts • clots close deeper cuts

42. Wound healing

43. HEALING OF WOUNDS • scabs = clots + dried tissue • scars result from connective tissue replacing skin • granulations form in large open wounds

44. Homeostatic imbalances of skin: • Skin cancer • Basal cell carcinoma = least malignant & most common – 30% of all white people get it • Squamous cell carcinoma - often on scalp & hands, grows rapidly and metastasizes • Melanoma = cancer of melanocytes, most dangerous type • ABCD rule: • Asymmetry, border irregularity, color, diameter

46. Burns • 1st degree = epidermis is damaged • ex. sunburn • 2nd degree = epidermis + part of the dermis are damaged, blisters occur • 3rd degree = epidermis + dermis + hypodermis are all damaged, nerve endings are destroyed • Evaluated by the “rule of nines”

48. Effects of aging: 1) Skin thins 2) Lubricating substances become deficient, so skin gets dry & itchy 3) Elastic fibers clump, skin loses elasticity 4) Sub Q fat layer diminishes, often cold • 3 & 4 cause wrinkles 5) Less melanocytes & Langerhan’s cells enhance the risk of skin cancer 6) Hair thins due to fewer active hair follicles