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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
Melanin
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
26
Skin color
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
27
Freckle
due to increased melanin production & accumulation in basal area of epidermis No increase in melanocytes
28
Mole
group of melanocytes in skin
29
Albinism
due to either absensce of tyrosinase activity or inability of cells to make up tyrosine Hereditary inability of melanocytes to syn melanin!
30
Vitiligo
Where melanocytes in skin are destroyed Some evidence it is autoimmune, gen & environmental combo
31
Langerhans cells
antigen presenting cells in stratum spinosum primarily Migrate to lymph nodes when process foreign antigens member of mononuclear phagocyte system
32
Mononuclear phagocyte sys
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
Dendritic nature of Langerhan's cells
34
Merkel cells
in stratum basale have desmosomes receive afferent n. terminals & f like touch R Contain granules
35
Dermis
type I coll fibers thick elasstic fibers dense irreg CT has superficial papillary layer & deep reticular layer
36
Blister
epidermis of skin separates from dermis pool of lymph & other bodily fluids accumulate
37
Skin properties
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
Wrinkling
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
Dermal papillus
contains capillaries that provide O2 & nutrients for the overlying AVASCULAR epidermis= NO BLOOD VESSLES!!!
40
Temp reg
Changes in blood flow to skin play central role in temp reg mainly vasoconstrict/vasodilate caps
41
Anastamose
arteriovenous anastomose open & metarteriole sphinceters close to epidermis diverts blood from outer part of body
42
Bruise
contusion injury to biological tissue in which the caps are damaged, allowing blood to seep into surrounding tissue
43
Birthmark
hemangioma- port wine stain Many new BVs group together in 1 place on the skin
44
Nerves
receive stimuli from environment corpuscle- rounded globular mass of cells, like P R on certain n. endings
45
Free n. endings
R for fine touch, heat, cold, pain, itching In stratum granulosum around most hair follicles
46
Merkel cells with their n. attachments
mechanoR In stratum basale Fingertips
47
Pacinian corpuscles
deep P R for mech & vibratory P In deeper dermis & hypodermis Contain mech gated ion channels
48
Meissner's corpuscle
touch R Dermal papillae below epiderm basal lamina contain mech gated ion channels lips, external genitalia, nipples
49
Ruffini's corpuscles
stretch R Deep layers of skin contain mech gated ion channels
50
Epidermal skin appendages
from down growths of epidermal epith during dev * hair follicles- hair * sebaceous glands- sebum * eccrine sweat glands- sweat * apocrine sweat glands- mixed product
51
Hair
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
Hair
prolif of matrix cells accounts for growth of hair homologous to stratum basale blood supply very important
53
Hair follicle & arrector pili m.
contraction of arrector pili m. causes gooseflesh Cutis anserina smoth m.
54
Glands in skin
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
Eccrine sweat glands
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
Secretory unit of eccrine sweat gland
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
Eccrine duct
lined by strat cuboidal epith Myoepith cells surround secretory portion
58
Apocrine sweat glands
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
Sebaceous glands
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
Nail
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
Wound healing
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
Scar
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
Keloid
bengin fibrous growths Can be a genetic predisposition w/ skin trauma Keloid scars, collagen production continues after it normally stops in scar production
64
Stretch marks
form of scarring Caused by dermis tearing/ wound repair in dermis
65
Burns
tissue is burnt, kills all cells
66
First degree
scald dividing keratinocytes of stratum basale spared, easily replenish upper layers
67
Second degree
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
Third degree
all keratinocytes/eptih cells destroyed only skin graft will replace epidermis
69
Sunburn
inflammatory rxn to UVR excessive one blistering sunburn doubles likelihood of developing malignant melanoma Involve his, PG & cytokines
70
Tattoo
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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