The integumentary system special class lec

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The integumentary system special class lec

  1. 1. THE INTEGUMENTARY SYSTEM Chona Araga, M.D.
  2. 2. COMPOSED OF:• 1. SKIN• Heaviest, largest single organ• 2.SKIN APPENDAGES: A.sweat gland B. sebaceous gland C. hairs D. nails
  3. 3. SKIN called integument• - also• - simply means covering• FUNCTIONS:5. Keeps water and other precious molecules in the body6. Keeps water out7. Protects the body from external agent8. Insulates and cushions deeper body organs9. Protects body from mechanical, chemical, thermal damage and also bacteria
  4. 4. FUNCTIONS• 6. Regulates heat loss from body surface• 7. Acts as mini-excretory system, urea, salt, water are lost when we sweat• 8. Manufactures several proteins important to immunity• 9. Storage of Vitamin D precursor• 10. Contains cutaneous receptors that serve as sensors for touch, pressure, temperature and pain
  5. 5. 2 PRINCIPAL LAYERS• 1. EPIDERMIS• 2. DERMIS
  6. 6. EPIDERMIS• Superficial protective layer of the skin• avascular• Composed of Stratified Squamous Keratinized Epithelium that varies in thickness• All but the deepest layers of epidermis are composed of dead cells• Composed of 4-5 layers, depending on its location within the body• Palms and soles have five layers because these areas are exposed to most friction
  7. 7. • Composed of keratinocytes,nonkeratinocytes melanocytes, Langerhans cells and Merkel’s cells• Constantly being regenerated every 20-30 days• Sequence of cytological changes of keratinocytes is referred to as cytomorphosis• Overlies projection of the dermis (dermal papillae), forming series of epidermal ridges• On the fingertips are visible as finger prints
  8. 8. 1. Stratum Basale (germinativum)• Deepest layer• Composed of single layer of cells in contact with the dermis• Cells are cuboidal to columnar keratinocytes• Mitotically active• Source of cells replacing the shed off superficial layers• Attached directly to the basal lamina by hemidesmosomes• Contains melanocytes and Merkel’s cells
  9. 9. Stratum Spinosum• Few layers of mitotically active polyhedral keratinocytes (prickle cell) which have extensions termed intercellular bridges now known to terminate in desmosomes• Also contains Langerhan’s cells• Part of Malphigian layer(stratum malphigii) : stratum spinosum and stratum basale• Upper aspect of this layer are keratinocytes containing membrane coating granules – Granules are released into intercellular space in the form of lipid containing sheets impermeable to water and foreign substances
  10. 10. Stratum Granulosum- Consists of only 3-4 flattened rows of keratinocytes that contain keratohyaline granules, bundles of keratin filaments and occassional monochromatic granules
  11. 11. Stratum Lucidum (Clear layer)4-6 rows of very thin, pale-staining, eosinophilic cells• Nuclei,organelles,and cell membranes are no longer visible so this layer appears clear• Exists only in the lips and the thickened skin of soles & palms• Contains a transluscent substance called eleidin
  12. 12. Stratum Corneum• 15-20 layers of flattened, scale-like anucleated cells, which arecontinuously shed as flake-like residues of cells• This surface layer is cornified and is the real protective layer of the skin• Cornification is brought on by keratinization and the hardening , flattening process that takes place as the cells die and are pushed to the surface• Friction at the surface of skin stimulates additional mitotic activity of stratum basale, resulting in the formation of a callus for additional protection• Continuously sheds cells by a process termed desquamation
  13. 13. Non keratinocytes in epidermis:1. Melanocytes- present in S. basale - synthesize the pigment melanin providing a protective barrier to UV radiation in sunlight2. Langerhan’s cell - located primarily in S. spinosum - possess long process (ddendritic cells), originate from monocytes - contain characteristic paddle-shaped Birbeck granules - antigen presenting cells
  14. 14. c) Tactile cells ( Merkel cell) - present in small number in S. basale - possess desmosomes and keratin filaments - pale cytoplasm containing small, dense-cored granules - aid in tactile (touch) reception
  15. 15. COLORATION OF SKIN • . CAUSED BY EXPRESSION OF A COMBINATION OF 3 PIGMENTS3.MELANIN4.CAROTENE5.HEMOGLOBIN
  16. 16. MELANIN• Brown-black pigment produced by the melanocytes of stratum basale• Guards skin against damaging effect of UV rays of sunlight• Gradual exposure to sunlight promotes increased production of melanin; hence tanning of skin• In albino, there is a normal number of melanocytes but lacks enzyme tyrosinase, that converts the amino acid tyrosine to melanin
  17. 17. • “freckles”- caused by aggregated patch of melanin “vitiligo”- lack of melanocytes in localized areas of the skin causing distinct white spots2. CAROTENE - a yellowish pigment found in epidermal cells & fatty parts of dermis - abundant in skin of Asians - together with melanin, accounts for the yellowish-tan color of Asians
  18. 18. 3. HEMOGLOBIN• Not a pigment of the skin, rather it is the oxygen-binding pigment found in RBc• Oxygenated blood flowing through the dermis gives the skin its pinkish tones
  19. 19. DERMIS• Deeper and thicker than the epidermis• A strong and stretchy envelope that helps to hold the body together• Blood vessels within the dermis nourish the living portion of the epidermis• With numerous collagenous, elastic and reticular fibers that give support to the skin• Highly vascular and glandular• Contains many nerve endings and hair follicles
  20. 20. Layers of Dermis1. PAPILLARY LAYER- in contact with epidermis- Accounts for about 1/5 of the entire dermis- With numerous projections called Dermal Papillae, that extend from the upper portion of the dermis into the epidermis- Dermal papillae contain capillary loops, which furnish nutients to the epidermis
  21. 21. - Some papillae house pain receptors (free nerve endings) and touch receptors (meissner’s corpuscles) - Dermal papillae form the base for the friction ridges on the fingers and toes
  22. 22. • Reticular layer – Deepest skin layer – Contains blood vessels, sweat & oil glands, and deep pressure receptors (Pacinian Corpuscles) – Many phagocytes are found here; they engulf bacteria that have managed to get through the epidermis – May contain Pacinian corpuscles and Krause’s end bulbs
  23. 23. Thick and Thin SkinThick skin (glabrous Thin skin (hairy skin) skin) 75-100 um thick• 400-600um thick Less prominent• Prominent corneum lacks S.corneum,well granulosum and developed S. lucidum granulosum and With hair follicles distinct S. lucidum sebaceous glands• Lacks hair and arrector pili follicles,sebaceous glands and arrector pili
  24. 24. SURFACE PATTERNS• 1. CONGENITAL PATTERNS + fingerprints or friction ridges - present on palms and soles - formed by the pull of elastic fibers within the dermis - function to prevent slippage when grasping objects
  25. 25. 2. ACQUIRED LINES• Deep Flexion Creases - found on the palms Shallow Flexion Lines - seen on knuckles and surface of other jointsFurrows in the forehead and face (wrinkles) - acquired from continual contraction of facial muscles, such as from smiling or squinting in bright light or against the wind; facial lines become more strongly delineated as one ages
  26. 26. LANGER LINESLines of tension produced by the orientation of collagen and elastic fibers in nonrandom pattern of arrangementLinear wound oriented parallel to langer lines tend to close and heal with minimum scarring, even if left unsuturedLinear wounds oriented perpendicular to langer lines tend to gape and heal slowly with consipicuous scarring if left unsutured
  27. 27. • Beneath the dermis lies the hypodermis (Gr. hypo, under, + derma, skin), or subcutaneous tissue, a loose connective tissue that may contain a pad of adipose cells, the panniculus adiposus.• The hypodermis, which is not considered part of the skin, binds skin loosely to the subjacent tissues and corresponds to the superficial fascia of gross anatomy.
  28. 28. CUTANEOUS GLANDS• 1. SEBACEOUS (OIL) GLANDS - found all over the skin, except on palms and soles - ducts usually empty into a hair follicle but some open directly onto skin surface - secretion is called sebum, a mixture of oily substance and fragmented cells that keep skin soft and moist and prevents hair from becoming brittle
  29. 29. • - if the drainage pathway for sebaceous glands becomes blocked for some reason, the glands may become infected, resulting in acne• - sebum also contains chemicals that kill bacteria• - become very active when sex hormones are produced in increased amounts during adolescence, thus skin is oilier during this period of life
  30. 30. • SWEAT GLANDS - also called sudoriferous glands - widely distributed in the skin; numerous in palms, soles, axillary and pubic regions - secretion evaporates and cools in the body6 TYPES: 1. Eccrine 2. Apocrine
  31. 31. ECCRINE SWEAT GLAND• - more numerous and found all over the body especially in forehead, back, palms and soles• Innervated by cholinergic fibers• Secretion reaches skin surface via a duct that opens directly on surface of skin through sweat pores• Secretion is mostly water with few salts
  32. 32. Secretory unit composed of:• 1. dark cells – secrete mucus-rich material• 2. clear cells – secrete a watery, electrolyte rich material• 3. myoepithelial cells – contract and aid nin expressing the gland’s secretion into the duct• Ductal unit is narrow and lined by stratified cuboidal epithelium
  33. 33. 2. APOCRINE SWEAT GLANDS• - much larger, localized gland found in axillary and pubic regions where they secrete into hair follicles• Not functional until puberty• Responsive to hormonal influence• Secretion is thick and rich in organic substances which is odorless when released but quickly broken down by bacteria into substances responsible for body odor• Innervated by adrenergic fibers
  34. 34. MAMMARY GLAND• Found within the breasts• Specialized sudoriferous or sweat gland that secrete milk during lactation• Under the stimulus of pituitary gland
  35. 35. ADIPOSE
  36. 36. HAIR• An invagination of the epidermis• Characteristic of all mammals, but its distribution, function, density and texture varies across mammalian species• Humans are relatively hairless, with only the scalp, face, pubis & axilla being densely haired• Men with more obvious hair because of the male hormone• Certain regions of body are hairless like the palms, soles, lips, nipples, penis,labia minore• Lifespan 3-4 mos for eyelashes, 3-4 yrs-scalp
  37. 37. Primary Function of Hair: Protectione.g. scalp hair, eyebrows- protectfrom sunlight
  38. 38. • PARTS OF HAIR: 1. Shaft – the visible but dead portion of hair projeting above surface of the skin• Consists of medulla,cortex and cuticle• 2. Root – enclosed in the follicle• 3. Bulb – terminal expanded region in which hair is rooted• Deeply indented by a dermal papilla which contains capillary loops for nutrition• Contains cells that form internal root sheath and medulla
  39. 39. • 1. Internal root sheath – deep to the entrance of sebaceous glands• Composed of Henle’s layer, Huxley’s layer and cuticle• 2. External root sheath• - direct continuation of the S. malphigii• Glassy membrane – noncellular layer• Separates the hair follicle from the surrounding dermal sheath
  40. 40. 3 DISTINCT KINDS OF HAIR IN HUMANS• 1. LANUGO – - fine, silky fetal hair that appears during the last trimester of development - Usually not evident on a baby at birth unless it has been born prematurely 2. ANGORA - grows continuously in length, as on scalp and on face of males
  41. 41. • 3. DEFINITIVE - grows to a certain length and then ceases to grow - most dominant type of hair e.g. eyelashes, eyebrow,pubic, and axillary hair- A sebaceous gland and an arrector pili muscle are attached to the hair follicle- When the muscle involuntarily contracts due to thermal or psychological stimuli, the hair follicle is pulled into an upright position, causing the hair to”stand on its end” and producing goosebumps
  42. 42. NAILS• Found on distal dorsum of each fingers and toes- Forms from a hardened, transparent, stratum corneum of epidermis- Consists of:- Nail Body - visible attached portion- Nail Root - part of the nail covered by skin
  43. 43. Nail Bed- where nail root and nail body are attachedFree edge - the distal exposed border attached to undersurface of hyponychiumHyponychium - beneath the free edge
  44. 44. Eponychium ( Cuticle) - covers the nail root - frequently splits causing a hangnailNail Matrix - proximal part of the nail bed - growth area of the nailLunula -whitish crescent (half moon) shaped area at the proximal aspect of nail
  45. 45. -Fingernails grow at approximately 1 mm per week- Growth of toenails is slower- nails are transparent and nearly colorless but they look pink because of the rich blood supply in the underlying dermis
  46. 46. Thank You

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