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MSK Test 1 > LEC-5 Integument System > Flashcards

LEC-5 Integument System Flashcards

1
Q

The skin, or integument, comprises about ___% of body weight.

A

16%

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2
Q

Tumors of the skin make up about ___% of all tumors.

A

30%

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3
Q

What is the most common skin malignancy and what causes it? Describe the histological characteristics.

A
  • Basal Cell Carcinoma (BCC)
  • Results from UV damgage to keratinocytes in stratum basale
  • Spherical nodules of hyperchromatic cells in the dermis
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4
Q

What are the five primary functions of the skin?

A
  • Absorption of UV light
  • Body temp. regulation
  • Corpuscles (sensory perception)
  • Defense against injury, dessication, bacteria
  • Excretion and absorption of sweat glands
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5
Q

What dermal layer is considered superficial fascia and not part of the skin?

A

Hypodermis

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6
Q

What dermal layer is made of stratified, squamous, and keratinized epithelium? What embryonic layer is it derived from and what does it contain?

A
  • Epidermis
  • Derived from embryonic ectoderm
  • Contains: Hair follicles, nails, sweat glands, and sebaceous glands
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7
Q

What dermal layer consists of dense, irregular connective tissue that contains the vascular supply for the skin? What embryonic layer is it derived from?

A
  • Dermis (contains vascular supply to the skin)
  • Embryonic mesoderm
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8
Q

What are the layers of the epidermis from superficial to deep?

A
  • Corneum
  • Lucidum
  • Granulosum
  • Spinosum
  • Basale
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9
Q

What is the principle cell type of the epidermis and what does it synthesize?

A
  • Keratinocyte (95% of epidermal cells)
  • Synthesizes intermediate filament keratin and secretes immune molecules?
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10
Q

What attaches the stratum basale to the basement membrane in skin?

A

Hemidesmosomes

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11
Q

What attach cells of the stratum basale to one another?

A

Desmosomes

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12
Q

Describe the stratum basale.

A
  • The stratum basale exists as a single layer of cuboidal cells in contact with the basement membrane.
  • This layer is highly mitotic and expresses intermediate filaments keratin-5 and keratin-14.
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13
Q

Describe the Stratum Spinosum.

A
  • Stratum spinosum = spinous layer
  • The stratum spinosum is the thickest layer of epidermis (thickest in thick skin)
  • It consists of polyhedral “prickle cells” and numerous intracellular bridges and desmosomes.
  • The basal-most region of this layer is mitotic and is in contact with the stratum basale.
  • It expresses keratin-1 and keratin-10 which form tonofilaments
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14
Q

What stratum layer expresses keratin-5 and keratin-14?

A

Stratum basale

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15
Q

What stratum layer expresses keratin-1 and keratin-10?

A

Stratum spinosum

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16
Q

What is Psoriasis Vulgaris?

A
  • A skin disorder that occurs through immune system activation (lymphocytes in papillary dermis)
  • It causes the hyperproliferation of keratinocytes with an accelerated cell cycle. Results in:
    • Increased stratum corneum and spinosum
    • Decreased stratum granulosum
  • It presents as reddish plaques with grayish, white scales.
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17
Q

What is Pemphigus Vulgaris?

A
  • A skin disorder in which IgG autoantibodies to cadherin proteins (desmoglein) in desmosomes causes breakdown of the epidermis.
  • Results in blisters and erythematous, crust and weepy erosions when blisters are broken
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18
Q

Describe the Stratum Granulosum.

A
  • The Stratum Granulosum = granular layer
  • Present primarily in thick skin (although not thickest layer)
  • Contains highest number of keratohyalin granules.
  • Highest synthesis and releases of membrane-coating granules.
  • Contains many desmosomes and forms claudin-containing occluding junctions within its own layer and with the stratum lucidum and corneum.
  • Cells in the superficial region of this layer undergo apoptosis and have no organelles.
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19
Q

Describe the Stratum Corneum.

A
  • The Stratum Corneum = cornified layer
  • Made of squames (flat, dead cells).
  • Consists of a compound cornified cell envelope of keratohyalin and keratin that also contains involucrin, loricrin, and small proline-rich proteins.
    • It maintains a lipid envelope of membrane-coating granule that forms a waterproof barrier.
    • Desquamation rate of this most superficial layer matches the mitotic rate of the basale and spinosum.
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20
Q

The second most common skin malignancy is known as _____________________. It is the result of insult by UV rays, irradiation, or chemical carcinogens to keratinocytes in the stratum spinosum. It may deeply invade the underlying tissue and metastasize.

A

Squamous Cell Carcinoma (SCC)

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21
Q

______________ make up 3% of the cells in the epidermis. They are derived from neural crest cells and migrate into the epidermis to differentiate into melanoblasts. They are present in the stratum basale; however, they do not form hemidesmosomes with other other cells, only basal lamina

A

Melanocytes

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22
Q

Melanocytes produce melanin pigment in specialized organelles called ____________.

A

Melanosomes

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23
Q

___________ is a protein that binds melanocortin receptors to activate signaling pathways that promote mitosis and production of melanin.

A

α-melanocyte stimulating hormone (α-MSH)

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24
Q

Dark pigment produced by melanocytes is referred to as ____________.

A

Eumelanin

25
Q

Light pigment produced by melanocytes is referred to as ____________.

A

Pheomelanin

26
Q

What is the pathway for melanin synthesis?

A

Tyorsine → DOPA (by tyrosinase; B6 cofactor) → Dopaquinone → Melanin

27
Q

Filamentous melanin accumulates to form structures known as ____________.

A

Melanosomes

28
Q

In what way are melanosomes transported?

A
  1. Transported along microtubules into dendrites
  2. Transferred to F-actin
  3. Taken to plasma membrane of dendrite
  4. Released by exocytosis
29
Q

Once released from dendrites, melanosomes are phagocytosed by ______________.

A

Keratinocytes

30
Q

(T/F) Once phagocytosed, melanosomes migrate to form a protective umbrella over the nucleus and nuclear DNA of the cell, guarding against UV rays

A

True.

31
Q

The tyrosinase enzyme, darkening of melanin, and endocytosis of melanosomes are increased in the presence of ___________.

A

UV rays

32
Q

In darker individuals, melanosome degradation by lysosomes is (quicker/slower).

A

Slower

33
Q

What are the four characteristics of a malignant melanoma that set it apart from a standard mole?

A
  • Asymmetry
  • Border irregularity
  • Color variation
  • Diameter (>6mm increases risk of malignancy)
34
Q

What is Vitiligo?

A
  • Patches of white area due to lack of pigmentation.
  • Melanocytes in this area have been destroyed due to autoimmune response.
35
Q

______________ are dendritic cells located in the stratum spinosum. They contain Birbeck granules and do not make desmosomal junctions with keratinocytes of the spinosum layer. These cells are derived from bone marrow and possess immune function, phagocytosing antigens and migrating to lymph nodes where the antigen is presented to T cells. These cells also play a role in a delayed (type IV) hypersensitivity response.

A

Langerhans cell

36
Q

_______________ are cells located in the stratum basale that function as mechanoreceptors. They are most abundant in the fingertips, are slowly adapting, and are used for discrimination of shapes and textures.

A

Merkel cells

37
Q

What embryonal layer is the dermis is derived from?

A

Mesoderm

38
Q

The dermis is separated from the epidermis by the ________________.

A

Basement membrane

39
Q

The dermis contains primarily type (I/II/III/IV) collagen.

A

Type I

40
Q

What are the two layers of dermis?

A
  • Papillary layer (superficial)
  • Reticular layer (deep)
41
Q

Describe the Papillary layer of the dermis.

A
  • Loosely woven connective tissue and dermal ridges that interdigitate with epidermal ridges.
  • Fibroblasts, immune system cells, capillaries, and arteriovenous anastomoses are all present within this layer of dermis.
  • It also features mechanoreceptors
    • Free nerve endings
    • Meissner corpuscles
    • Krause corpuscles
42
Q

Describe the Reticular layer of the dermis.

A
  • Coarser, denser connective tissue.
  • Larger blood vessels and lymphatic vessels are present, along with fibroblasts, sweat glands, hair follicles, arrector pili muscles, sebaceous glands,
  • Mechanoreceptors:
    • Pacinian corpuscles
    • Ruffini corpuscles.
43
Q

(Pacinian/Ruffini/Meissner) corpuscles are important for detecting tensile force.

A

Ruffini

44
Q

(Pacinian/Ruffini/Meissner) corpuscles are important for detecting pressure, vibration, course touch, and tension.

A

Pacinian

PCPVC

45
Q

(Pacinian/Ruffini/Meissner) corpuscles are important for detecting light touch.

A
  • Meissner
  • In dermal papillae

MCL

46
Q

Meissner corpuscles are located in the (papillary/reticular) dermis.

A

Papillary

47
Q

(T/F) Pacinian and ruffini corpuscles are important sources of regenerative keratinocytes in cutaneous wound healing.

A

False. Pacinian and ruffini corpuscles only serve as mechanoreceptors.

  • Hair follicles and ducts of glands (sebaceous and sweat) are important sources of regenerative keratinocytes in cutaneous wound healing.
48
Q

What are the two types of sweat glands?

A
  • Eccrine
  • Apocrine
49
Q

______________ produce a cornified shaft of dead cells that grow by proliferation of keratinocytes within a matrix.

A

Hair follicles

50
Q

_____________ within the matrix of a hair follicle determine hair color.

A

Melanocytes

51
Q

___________ muscles connect to the papillary dermis of a hair follicle.

A

Arrector pili

52
Q

Which type of sweat glands are located in the axilla, anus, areola, auditory canal, and eyelids?

A

Apocrine

53
Q

Which type of sweat glands secrete an odorless, viscous secretion and what is the mechanism by which this is accomplished?

A
  • Apocrine sweat gland
  • Merocrine mechanism
  • Duct opens into hair follicle or onto epidermis
  • Hormonally responsive
  • Have contractile epithelial cells
54
Q

Which type of sweat glands consist of two layers of stratified cuboidal cells that resorb potassium, sodium, and chloride ions? These glands secrete urea and lactic acid.

A

Eccrine

55
Q

Describe the duct and secretory unit of Eccrine sweat glands.

A
  • Duct: Coiled tubular duct
    • Stratified cuboidal (2 layers)
    • Resorbs K+, Na+, Cl-
    • Excretes urea and lactic acid
  • Secretory Unit:
    • Merocrine mechanism
    • Dark cells with mucous secretion
    • Clear cells with aqueous secretion
    • Contractile myoepithelial cells
56
Q

Describe Sebaceous sweat glands.

A
  • Branched tubuloalveolar glands
  • Duct
    • Opens into hair follicles.
  • Secretory Unit
    • Holocrine mechanism and consist of an oily sebum
    • Hormonally responsive.
57
Q

The (hyponychium/eponychium) refers to the cuticle overlying the opaque, pale region of the nail plate.

A

Eponychium

58
Q

The (hyponychium/eponychium) refers to area located under the free edge of the nail.

A

Hyponychium

59
Q

Describe the Stratum Lucidum.

A
  • The Stratum Lucidum = clear and translucent layer.
  • Most prominent in thick skin (although not thickest layer)
  • Contains large amounts of keratohyalin and tonofibrils.
  • Comprised of dead cells with no organelles.

MSK Test 1 (11 decks)

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