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Microanatomy > Skin > Flashcards

Skin Flashcards

1
Q

Epidermis

A

keratinized stratified squamous epith

Epidermis derived from ectoderm

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2
Q

Dermis

A

dense CT

Dermis derived from mesoderm

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3
Q

Hypodermis

A

subcutaneous tissue

not considered part of skin

Contains adipose

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4
Q

Epidermis Characteristics

A

Has deep invaginations- epidermal pegs

which interdigitate w/ dermis projections called dermal paipple

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5
Q

Thick & thin skin

A

Thick skin on palms of hands & soles of feet- no hairs

Thin skin has hairs & found everywhere else

Thickness depending on epidermis

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6
Q

Epidermis Breakdown

A

4 layers in thin skin

strat squamous

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7
Q

Keratinocytes

A

begin life @ bottom layer & as move up

cease dividing, diff, die & sloughed off (desqamation)

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8
Q

Stratum Basale

A

1 layer @ BM at dermal-epidermal junction

Contains stem cells w/ intense mitotic activity

As cells progress upwards, number of keratin intermed filaments increases until keratins represent half the total protein in stratum corneum

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9
Q

Stratum spinosum

A

Prickle cells- polyhedral keratinocytes; few layers

Desmosomes give them spiny or prickly appearance

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10
Q

Stratum Germanitivum

A

cells of lower stratum spinosum & stratum basale

only keratinocytes that divide!

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11
Q

Tonofilaments

A

another word for keratin intermed filaments in skin

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12
Q

Stratum granulosum

A

most superficial layer in which nuclei are still prsent

Cytoplasm w/ basophilic granules called keratohyalin granules!

Substance in keratohyalin granules binds w/ keratin filametns

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13
Q

Stratum granulosum & stratum spinosum

A

Both contain lamellar granules (lamellar bodies)

Lamellar granules- small rodlike structures formed by lipid bilayers

Discharge their content into IC space of stratum granulosum to be deposited as lipid sheets.

Barrier to penetration by foregin mat= sealing effect of skin

“waterproof” skin

LIKE INTERCELLULAR CEMENT

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14
Q

Stratum lucidum

A

clear layer just superficial to stratum granulosum

Can be observed only in palmar & plantar thick skin

Has keratinocytes w/o nukes or organelles just keratin filaments

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15
Q

stratum corneum

A

15-20 layers of dead cells

Non viable & scale like= squames

OUtermost layer is shed by desqamation

Much thinner in thin skin than thick skin

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16
Q

Changes of Keratinocytes

A
  1. mitotically active- statum bsale & lower spinosum
  2. nuke & organelles- up to stratum granulosum
  3. keratin/tonofilaments- get more as you move until top layer
  4. waterproof- granulosum & above
  5. desmosome- almost to top but not in stratum corneum
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17
Q

Thick skin

A

lines palms of hands & soles of feet

lack hair follicles

lack sebaceous glands

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18
Q

Thin Skin

A

Has epidermis

all over body

contains hair follicles & sebaceous glands

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19
Q

In thin skin

A

indiv cells of stratum granulosum & stratum lucidum are scattered at interface of stratum spinosum & stratum corneum.

Even though these 2 layers are absent or not well defined!

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20
Q

Callous

A

thickening of stratum corenum from P on A of skin

Most often in thick skin

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21
Q

Wart

A

benign epidermal growth due to papilomavirus infection of keratinocytes

Salicylic acid is Rx

  • dissolves keratin (keratolytic)
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22
Q

Nonkeratinocytes in epidermis

A

melanocytes- syn dark brown pigment melanin

langerhan’s cells- APCs

Merkel cells- sensory mechanoR w/in nuero endocrine f

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23
Q

Melanocytes

A

Derived from NC cells

scattered among basal cells of stratum basale

Melanin begins to be degraded by lysosomes soon after it enters keratinocytes

Can replicate throughout their life, although much slower than keratinocytes

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24
Q

Melanocytes

A

syn melanin from tyrosine then transfer pigment into keratinocytes

Tryosinase syn in RER & accumulates in vesicles in Golgi & then as free vesicles= mealnosomes

Melanin syn begins in stage II melanosome & forms stage III melanosomes

Melanin granule is after stage III loses its tyrosinase activity

transferred to keratinocytes of malpighian layer (stratum basale & stratum spinosum) from melanocyte’s processes

Tyrosinase activated by UV light, this is why you tan when exposed to sun

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25
Q

Melanin

A

melanin lies between sun & nuke

melanin protects DNA from UV radiation of sun

This explains why people with lighter skin have higher incidence of skin cancer

Cells of darker skinned people tend to contain more melanosomes & these can be found throughout cytoplasm

pic of stratum spinosum w/ melanin deposits

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26
Q

Skin color

A

determined by ratio of melanocytes to keratinocytes

not by number of melanocytes

dark skinned & light skinned have same number of melancoytes

but dark skinned make more melanin

light skinned people degrade melanin faster in keratinocytes

light skinned have most of melanosomes in basal layer keratinocytes

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27
Q

Freckle

A

due to increased melanin production & accumulation in basal area of epidermis

No increase in melanocytes

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28
Q

Mole

A

group of melanocytes in skin

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29
Q

Albinism

A

due to either absensce of tyrosinase activity

or

inability of cells to make up tyrosine

Hereditary inability of melanocytes to syn melanin!

30
Q

Vitiligo

A

Where melanocytes in skin are destroyed

Some evidence it is autoimmune, gen & environmental combo

31
Q

Langerhans cells

A

antigen presenting cells in stratum spinosum primarily

Migrate to lymph nodes when process foreign antigens

member of mononuclear phagocyte system

32
Q

Mononuclear phagocyte sys

A

chars of CT surrounding newly formed macrophages determine exact final differentiation

If it is dermis then diff into Langerhan’s & then enter epidermis

If bone become osteoclasts etc.

All develop as monocytes in Bone Marrow & enter blood & CT to develop into macrophages

33
Q

Dendritic nature of Langerhan’s cells

A
34
Q

Merkel cells

A

in stratum basale

have desmosomes

receive afferent n. terminals & f like touch R

Contain granules

35
Q

Dermis

A

type I coll fibers

thick elasstic fibers

dense irreg CT

has superficial papillary layer & deep reticular layer

36
Q

Blister

A

epidermis of skin separates from dermis

pool of lymph & other bodily fluids accumulate

37
Q

Skin properties

A

collagen & elastic fibers in CT of dermis give skin its elastic & resilient texture

When fibers degrade w/ age cause wrinkling & loss of elasticity of skin

38
Q

Wrinkling

A

degen of collagen & elastic fibers in dermis

in old age:

  • extensive cross linking of coll fibers & loss of elastic fibers

any time

  • degen of these fibers caused by excessive exposure to sun
  • Sun exposure causes skin to become more fragile, lose suppleness & wrinkle

extra melanin in dark skinned indivs blocks UV rays

39
Q

Dermal papillus

A

contains capillaries that provide O2 & nutrients for the overlying AVASCULAR epidermis= NO BLOOD VESSLES!!!

40
Q

Temp reg

A

Changes in blood flow to skin play central role in temp reg

mainly vasoconstrict/vasodilate caps

41
Q

Anastamose

A

arteriovenous anastomose open & metarteriole sphinceters close to epidermis

diverts blood from outer part of body

42
Q

Bruise

A

contusion

injury to biological tissue in which the caps are damaged, allowing blood to seep into surrounding tissue

43
Q

Birthmark

A

hemangioma- port wine stain

Many new BVs group together in 1 place on the skin

44
Q

Nerves

A

receive stimuli from environment

corpuscle- rounded globular mass of cells, like P R on certain n. endings

45
Q

Free n. endings

A

R for fine touch, heat, cold, pain, itching

In stratum granulosum

around most hair follicles

46
Q

Merkel cells with their n. attachments

A

mechanoR

In stratum basale

Fingertips

47
Q

Pacinian corpuscles

A

deep P R for mech & vibratory P

In deeper dermis & hypodermis

Contain mech gated ion channels

48
Q

Meissner’s corpuscle

A

touch R

Dermal papillae below epiderm basal lamina

contain mech gated ion channels

lips, external genitalia, nipples

49
Q

Ruffini’s corpuscles

A

stretch R

Deep layers of skin

contain mech gated ion channels

50
Q

Epidermal skin appendages

A

from down growths of epidermal epith during dev

  • hair follicles- hair
  • sebaceous glands- sebum
  • eccrine sweat glands- sweat
  • apocrine sweat glands- mixed product
51
Q

Hair

A

Glassy mem- thick BM separates dermis from epith of hair follicle

Hard keratin from hair

soft keratin from epidermis of skin

Melanoctyes give hair its color, transfer melanin to epith cells like in skin

52
Q

Hair

A

prolif of matrix cells accounts for growth of hair

homologous to stratum basale

blood supply very important

53
Q

Hair follicle & arrector pili m.

A

contraction of arrector pili m. causes gooseflesh

Cutis anserina

smoth m.

54
Q

Glands in skin

A

eccrine sweat glands- sweat, all over body

apocrine- only in arm pit, areola of nipple & anal region. Odorless product upon secretion but when metabolized by bac presents distinctive odor

sebaceous gland- through body but not in thick skin, sebum

55
Q

Eccrine sweat glands

A

sweat is product

simple coiled, tubular glands

Secretion of merocrine

Very important for thermoregulation

Sweat pore allows for duct to pass from secretory portion of gland across dermis & epidermis

Not associated w/ hair follicles!

56
Q

Secretory unit of eccrine sweat gland

A

dark cells- line lumen of gland, contain mucinogen rich granules

clear cells- underlie dark cells, watery & electrolyte rich material

myoepith cells- contract & aid in expressing gland’s secretions into duct **

57
Q

Eccrine duct

A

lined by strat cuboidal epith

Myoepith cells surround secretory portion

58
Q

Apocrine sweat glands

A

Ducts open into hair follicles

Secrete phermones in animals but in humans ??

Very wide lumen comapred to eccrine (b/c store product in lumen)

59
Q

Sebaceous glands

A

sebum- oily & degent epith cells

Sebum prevents H2O loss from skin & lubricates hiar but weak antibac & antifungal properites

Found in face & scalp in abundance- acne contributor

Starts @ puberty

holocrine secetion- prod of secretion released w/ remnants of dead cells

Stem cells in base of gland prolif to replace lost cells

60
Q

Nail

A

nail or nail plate hard keratin plate growing out of nail be d

Nail bed is special epith with same epidermis layers

Nail plate= stratum corneum

Nail plate hard, tight, keratinized epidermal cells

Nail body, free dedge into dermis to form nail root/groove

Prolif in nail root form nail matrix & nail elongates

61
Q

Wound healing

A
  1. Injury
  2. Coagulation - both after wounding & blood clots
  3. early inflammation, neutrophils dom cell type
  4. late inflammation, macrophages dom cell type & being replaced by fibroblast to secrete collagen
  5. remodeling, fibroblasts repair
62
Q

Scar

A

fibrous tissue composed of coll formbed by fibroblasts

Collagen & scarring are glue by which human body heals wound

Have to reform epith layer of keratinocytes if you dont get stiches after a deep cut & can fill with collagen thus causing a scar

63
Q

Keloid

A

bengin fibrous growths

Can be a genetic predisposition w/ skin trauma

Keloid scars, collagen production continues after it normally stops in scar production

64
Q

Stretch marks

A

form of scarring

Caused by dermis tearing/ wound repair in dermis

65
Q

Burns

A

tissue is burnt, kills all cells

66
Q

First degree

A

scald

dividing keratinocytes of stratum basale spared, easily replenish upper layers

67
Q

Second degree

A

stratum basale of upper epidermis destroyed, but dividing epith cells/keratinocytes can migrate upwards from around hairs deeper in dermis.

Blister forms due to damaged caps of dermis

68
Q

Third degree

A

all keratinocytes/eptih cells destroyed

only skin graft will replace epidermis

69
Q

Sunburn

A

inflammatory rxn to UVR excessive

one blistering sunburn doubles likelihood of developing malignant melanoma

Involve his, PG & cytokines

70
Q

Tattoo

A

Pigments into dermis of skin

Lasers can be used to be removed- break up the pigment so it can be digested by macrophages

Region can become lightened

Microanatomy (9 decks)

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