A&P 8

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  1. what are the 3 layers of INTEGUMENT (SKIN) STRUCTURE from superficial to deep?
    • 1. epidermis
    • 2. dermis
    • 3. subcutaneous (hypodermis) (fat)
  2. describe EPIDERMIS
    • 1st layer of integument
    • mostly comprised of dead cells, which have expelled their nucleus & all organelles & become simply bags of keratin (protein)
  3. describe DERMIS
    • 2nd layer of integument- living layer of tissue underneath epidermis
    • contains blood vessels, nerves, glands, & living skin cells
    • hair roots are found in the dermis & small bit of muscle (arrector pili), which controls the angle of each hair
  4. describe SUBCUTANEOUS
    • 3rd layer of integument- beneath dermis
    • not technically part of skin, bu a layer of areolar &/or adipose connective tissue
  5. define DERMATOLOGY
    branch of medicine that treats diseases of the skin
  6. define PEMPHIGUS
    • dermatological disease that is very troubling, involves an autoimmune attack against the desmosomes
    • patient mounts an immune defense against the proteins of his own desmosomes & hemidesmosomes- skin of these patients literally falls apart
  7. list the layers of skin (epidermis)
    • skin is a keratinized stratified squamous epithelium
    • layers:
    • stratum basale
    • stratum spinosum
    • " " granulosum
    • " " lucidum
    • " " corneum
    • from deepest to superficial: Before Signing, Get Legal Counsel
    • from superficial to deepest: Cher Likes Getting Skin Botoxed
  8. discuss KERATINOCYTES
    • all layers of the epidermis (not vascular) contain keratinocytes
    • in general, living keratinocytes are found in the deeper layers (starting w/ basale- generates keratinocytes through cell division)
    • as 1 moves more superficially, dead keratinocytes predominate
    • stratum corneum consists entirely of 2 dozen rows of dead, flat keratinocytes w/ no other cell types present
  9. define SQUAMES
    once corneocytes are shed from stratum corneum, the shed flakes
  10. about how much do humans shed per hour?
    600,000 dead keratinocytes
  11. describe the BASALE LAYER
    • deepest layer of epidermis
    • constant cell division, layer from which all others regenerate
    • cells divide & grow, then migrate upwards (superficially), losing their nuclei & organelles, become bags of keratin (keratinocytes)
  12. describe the remaining 4 layers of epidermis: spinosum, granulosum, lucidum, & corneum
    • corneum- "horn like" most superficial of layers, when it's still attached-corneocytes, they are constantly shed
    • lucidum- "clear" only in thick skin
    • granulosum- "grainy" lipid granules
    • spinosum- "spiny"
  13. what does Dermatophagoides pteronyssinus (tiny mite) eat?
    our dead skin flakes (their primary source of food)
  14. describe THIN SKIN
    • (hairy skin)- covers everything except palms, fingertips, & soles of feet
    • LACKS stratum lucidum- spinosum & corneum are very thin
    • epidermal thickness- .10-.15 mm
    • lacks epidermal ridges due to poorly developed & fewer, less-well-organized dermal papillae
    • hair follicles, arrector pili muscles, & sebaceous glands are present
    • few sudoriferous glands
    • sparse sensory receptors
  15. describe THICK SKIN
    • aka- glabrous skin
    • found on palms, palmar surface of digits, & soles of feet
    • HAS a prominent stratum Lucidum
    • epidermal thickness- .63-4.5 mm, the increased thickness is because of spinosum, lucidum, & corneum
    • epidermal ridges are present due to well developed & more numerous dermal papillae organized in parallel rows
    • hair & sebaceous glands are absent
    • more numerous sudoriferous glands
    • denser sensory receptors
  16. what are the 4 cell types found in the epidermis?
    • dead keratinocytes
    • melanocytes
    • langerhans cells
    • & merkel disc
  17. explain DEAD KERATINOCYTES (1 of 4 cell types in epidermis)
    • cell membrane surrounding the protein keratin
    • make up about 90% of cells in epidermis
  18. explain MELANOCYTES (1 of 4 cell types in epidermis)
    • make up about 8% of cells in epidermis
    • carry melanin pigment granules that give skin its color
  19. explain LANGERHANS CELLS (1 of 4 cell types in epidermis)
    • more rare
    • is the skin's version of a type of immune defense cell (dendritic cell)
    • macrophages of epidermis (phagocytosis)
  20. explain MERKEL DISC (1 of 4 cell types in epidermis)
    • rarest of the cells in epidermis
    • nervous system cell that detects light touch
  21. what are the 5 functions of the epidermis (skin)?
    • 1. waterproof
    • 2. cushion & protect deeper tissues
    • 3. excrete wastes
    • 4. regulates temperature
    • 5. provide sensory information
  22. explain STEM CELLS found in stratum basale
    • full of intermediate filament protein keratin
    • these divide to regenerate skin keratinocytes
    • cells terminally differentiate as they more more superficially
    • eventually lose nuclei & become just keratin surrounded by membrane
    • also secrete lipids that give skin waterproof & flexible properties
  23. what are the 3 classes of pigments?
    • melanin
    • hemoglobin
    • cartotene
  24. what are the 2 types of melanin? and give their color & an example
    • pheomelanin- which is yellow-red, ex: freckle
    • eumelanin- which is brown- black, ex: mole
    • in hair, both of these are scattered among the keratin fibers
  25. describe MELANIN (1 of 3 classes of pigments)
    • there are 2 types: pheomelanin & eumelanin
    • in hair they are scattered among keratin fibers, in skin they are found in cells called melanocytes
    • almost everyone has roughly the same # of melanocytes (people differ in the amount of pigment in each melanocyte)
    • pigment is transferred to keratinocytes, giving hair & epidermis their color
    • melanocytes are normally scattered more-or-less evenly throughout the epidermis, mostly in deeper layers (spinosum & basale) when they accumulate in one region, a mole results
  26. describe HEMOGLOBIN (1 of 3 classes of pigments)
    • red pigment in blood that gives the skin a pinkish cast
    • light skin- decrease melanin storage
    • skin color hemoglobin adds color
  27. describe CAROTENE (1 of 3 classes of pigments)
    • forms deposits in the skin
    • precursor to vitamin A found in intensely colored fruits & veggies
    • when you eat too many carrots & toms- turn orange
  28. discuss BILIRUBIN & JAUNDICE
    • in some diseases, such as liver failure, pigment bilirubin accumulates in the skin giving it a yellow color- this is not normal skin pigment
    • they symptom of turning yellow (especially in whites of eyes) is called jaundice
  29. describe the DERMIS layer
    • dense connective tissue layer, beneath the epidermis
    • few cells, mostly contains collagen (strength) & elastic (stretch) fibers
    • there are 2 regions of the dermis (from superficial to deep): papillary region (superficial) & reticular region
    • stretching can cause tears in the dermis- striae ("stretch marks")
  30. describe the PAPILLARY REGION
    • 1/5 of the dermis layer
    • consists of areolar connective tissue containing thin collagen & elastic fibers
    • surface area is greatly increased by dermal papillae- contain capillary loops, Meissner corpuscles (sensitive to touch), & free nerve endings(warm, cool, pain, tickling, & itching)
    • *important for its attachment to the epidermis
    • causes the skin to have fingerprints
  31. describe the RETICULAR REGION
    • remaining 4/5 of the dermis layer
    • attached to subcutaneous layer
    • contains nerves, blood vessels, hair roots, & glands
    • consists of dense irregular connective tissue containing fibroblasts, collagen, & some elastic fibers
    thermoregulation-conserve heat
  33. describe VASODILATION
    thermoregulation- dissipate heat
  34. describe the SUBQ
    • not typically included in the skin
    • loose connective tissue made up of areolar & adipose tissues
    • blood vessels pass through this layer on their way to the dermis
    • lamellated (Pacinian) corpuscles are found in the lower dermis and upper part of the subQ layer
    • insulation/ attaches dermis to muscle tissue
    a kind of nerve ending mediating the feeling of vibration
  36. what are the 4 sensory receptors & where are they located?
    • 1. meissner (touch) corpuscles- light touch
    • 2. merkel (tactile) disks- light touch (lighter than meissner)
    • 3. free nerve endings- pain, temp, itch, hair movement
    • 4. Pacinian (lamellated(layered like an onion)) corpuscle- deep pressure, vibration
    • meissner corpuscles, merkel discs, & free nerve endings are located at the interface b/n epidermis & dermis, in the papillary region
    • deep in the skin, at border of dermis & subQ layer is the pacinian (lamellated) corpuscle
  37. what are the the 2 skin glands?
    • sudoriforous glands- sweat
    • sebaceous glands- oil
    • they are sweat glands, there are 2 types:
    • Eccrine & Apocrine
  39. describe ECCRINE sweat glands
    • used to cool skin, waste removal & restore homeostasis (thermoregulation- control of body temp)
    • located throughout most regions of body, especially in forhead, palms, & soles
    • location of secretory portion is mostly in deep dermis
    • the termination of excretory duct is @ surface of epidermis
    • secretion is less viscous (more watery)
    • it's stimulated during emotional stress
    • onset is soon after birth
  40. describe APOCRINE sweat glands
    • associated w/ hair shaft
    • it's located in hair regions
    • location of secretory portion is mostly in subQ layer
    • the termination of excretory duct is @ hair follicle
    • secretion is viscous, same as eccrine plus lipids & proteins
    • stimulated during emotional stress & sexual excitement- there are traces of fat-soluble substances-pheromones- that participate in sexual response
    • onset @ puberty
  41. describe SEBACEOUS GLANDS
    • oil glands
    • associated w/ hair shaft
    • secretes waxy substance- sebum- to promote health of hair
    • becomes active @ puberty in response to androgens
  42. describe NAILS (anatomy & function)
    • free edge- hangs over, loses contact w/ living tissues
    • nail body (plate)- clear, tough, hard, dense covering made of keratin, tightly packed
    • lunula ("little moon")- seen near cuticle, slightly lighter area
    • eponychium (cuticle)- fills space where epidermis ends
    • nail root- underneath actual nail, goes past the cuticle
    • nail matrix- layered underneath nail root, rapidly dividing cells, loss of nail matrix=loss of nail
    • hyponychium (nail bed)
  43. describe HAIR (anatomy & associated structures)
    • specialized form of keratin
    • external (visible) portion of hair is 3 concentric layers: medulla (in center), cortex (further out), & cuticle (covering on the outside)
    • beneath the surface of skin, hair follicle & dermal root sheath surround medulla, cortex, & cuticle
    • @ the base there are blood vessels & melanocytes
    • color comes from pigment granules trapped along w/ keratin protein in hair shafts (brown or black eumelanin & blonde or red- pheomelanin)
    • white/gray occurs when pigment production is reduced or halted & air bubbles replace pigment
    • hair root (3 layers): cuticle of hair, cortex, & medulla
    • hair follicle (6 layers) same 3 & an additional 3: internal root sheath, external root sheath, & dermal root sheath
    • order of everything from inside to out: medulla (innermost), cortex, cuticle of hair, internal root sheath, external root sheath, & dermal root sheath (outermost)
    • below skin is the same in addition to (from top to bottom) hair matrix (right below medulla), papilla of hair- there are also melanocytes & blood vessels
  44. what are the 3 cycles of hair follicles & describe?
    • growth (anagen) stage- hair shaft elongates, lasts 2-6 yrs
    • regression (catagen) stage-cells stop dividing, lasts 2-3 wks
    • resting (telogen) stage- hair (shaft) falls out, lasts 3 mnths
  45. thin vs thick skin- hair, sweat glands, & sebaceous glands- present or not?
    • thin (NO- Stratum Lucidum):
    • hair- present sweat glands- fewer sebaceous- present
    • thick (YES- Stratum Lucidum):
    • hair- absent sweat glands- more sebaceous-absent
  46. describe development of layers of skin
    • skin develops from outermost of the 3 embryonic layers, called the ectoderm
    • by 4th week (2 simple layers)- ectoderm turns into skin, mesenchyme turns into connective tissue
    • by 11th week (3ish layers, wavy)- dermis & epidermis are evident, basale layer actively dividing cells
    • by 14th week- beginning of 2nd trimester (same w/ roots developing)- prescursors of sweat glands & hair bulbs are evident
    • by 18th week (same, but thicker & w/ hair & deeper roots)- hairs pop out on the surface
  47. describe NEURAL CREST
    • melanocytes (they are among the last skin cells to arrive) migrate into skin here
    • location near spinal cord
  48. define ROSACEA
    • common disease of aging skin
    • characterized by dilated blood vessels & pimples, especially around nose & cheeks
    • cause is unknown
  49. describe AGING SKIN decreases
    • decreases:
    • # langerhans cells
    • # mast cells, melanocytes
    • inflammatory response
    • thermoregulation (sweat glands, vascularity, subQ fat)
    • capillary loops in skin
    • mechanoreceptors
    • speed of wound healing
  50. describe AGING SKIN increases & other
    • increases:
    • risk of skin cancer & infections
    • increased tendency to tear
    • more wrinkles, sagging
    • atrophy of hair bulbs, sweat, sebaceous glands
    • also:
    • flattening of dermal papillae & epidermal ridges (rete ridges)
    • changes in collagen , elastin
    • don't penetrate epithelium
    • dividing cells of the stratum basale migrate into the "pit" of the wound, if necessary
    • normal process of cell division produces nucleated keratinocytes
    • finally these get pushed upward by the newly-divided keratinocytes as they mature into corneocytes
  52. describe DEEP WUND REPAIR
    • deep wounds penetrate blood vessels
    • blood fills wound & then clots into semi-solid mass
    • monocytes in clot mature into macrophages; neutrophils in clot work w/ macrophages to destroy invaders
    • cells of stratum basale migrate inward to replace the epidermis
    • fibroblasts migrate into dermal portion of clot, lay down new fiber matrix (to restore function & appearance of dermis)
    • if restoration of dermis is not complete, a scar may be left behind
  53. describe steps in formation of DECUBITUS ULCER (pressure ulcer)
    • they are lesions that result from disruption of skin homeostasis
    • areas where bone is close to surface are prone to pressure ulcers- there is less cushioning from adipose & muscle tissue
    • skin becomes trapped b/n fixed point (bed, cast, splint, floor) & blood supply is lost
    • few hours of lost blood supply may produce discoloration of affected area, but damage is not permanent
    • if pressure continues for longer time, small cracks develop in skin & skin flora begin dividing
    • w/out immune cells carried by blood, infection spreads throughout a large area & tissue necrosis results
  54. discuss the 3 different burn degrees
    • 1st degree (sunburn)- only the epidermis is involved, skin reddens, no permanent damage & skin returns to normal in under a week
    • 2nd degree- heat energy penetrates deeply both epidermis & dermis are damaged, blood vessels leak fluid (though not cells) blisters form (as skin fills w/ filtrate of blood), hair follicles & glands are typically not damaged
    • 3rd degree (full-thickness burn)- destroys ALL layers of skin, cells die & skin function is lost in affected area, dead skin may be black, cherry-red, or ash- white
  55. explain "rule of 9's" (% of body burned)
    • head & neck- total(anterior/posterior)= 9
    • trunk- total(anterior/posterior)= 36
    • each arm- total(anterior/posterior)= 9
    • each leg- total(anterior/posterior)= 18
    • perineum- 1
  56. discuss ADIPOSE & THERMOREGULATION (importance of skin in maintenance of body temp)
    • 2 primary thermoregulatory mechanisms: circulation & sweating
    • arrector pili also helps constrict blood vessels ("goosebumps")
    • adipose tissue in subQ layer insulates these blood vessels
    • sweat glands (apocrine & eccrine) shed heat by evaporation
    • too cold: blood vessels in dermis constrict, conserving heat
    • too hot: blood vessels in dermis dilate, shedding heat
    • vasoconstriction- pale (to the left of pic)
    • vasodilation- red skin (to the right of pic)
  58. what are the 3 main types of SKIN CANCER
    • from most common, least deadly to rare, worst
    • 1. basal cell carcinoma- most common, usually seen on face, caused by sun exposure, cancerous but rarely metastatic (doesn't travel to distant sites), generates from stratum basale
    • 2. squamous cell carcinoma- 2nd most common, usually seen on face, caused by sun (uv) exposure, cancerous & will metastasize (travels to distant sites through lymphatic system), generates from flat/scale keratinocytes
    • 3. melanoma- rare & worst prognosis, frequently metasttasizes, ABCDE criteria: asymmetry, border, color, diverse structure, & elevation
    • NOT a cancer, but a predisposition to cancer
    • lacking DNA repair, multiple skin cancers are common
  60. describe way in which CANCER FORMS & SPREADS
    • melanocytes evenly throughout the epidermis
    • most abundant in spinosum & basale
    • accumulation in a region- mole
    • color/ margins/ size----cancer
    • start- genetically altered epithelial cell
    • 2nd- Hyperplasia- abnormal increase in # of cells in tissue or organ, increasing its size
    • 3rd- Dysplasia, during which cancerous cells appear in center of mass
    • 4th- In situ cancer, w/ cancerous cells in center multiplying rapidly
    • 5th- Malignant tumor (cancer) showing metastasis
  61. explain mechanism by which HANDWASHING reduces transmission of disease
    • 7% (of the 600,000) 42,000 are contaminated w/ viable organisms- most common organisms associated w/ shed skin are staphylococcus & enterococcus
    • klebsiella are bacteria which commonly cause pneumonia in hospitals
    • skin has normal flora constantly being shed
    • handwashing & alcohol-based hand cleaners are used to reduce # of viable organisms- iodine scrubs
Card Set:
A&P 8
2012-03-30 15:03:18

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