Integument I Flashcards

1
Q

What is the general organization of the integument?

A

epidermis, basement membrane, dermis, subcutaneous tissue

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2
Q

What are some synonyms for subcutaneous tissue?

A

SubQ, superficial fascia, hypodermis

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3
Q

What are the types of epidermal ridges?

A

primary dermal ridge, interpapillary peg, secondary dermal ridges, dermal papillae

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4
Q

Describe primary dermal ridges

A

• Related to finger prints • Found everywhere except forehead, external ear, perineum, and scrotum • Formed during 3rd to 4th months of fetal life • Subdivided into two secondary dermal ridges by interpapillary peg

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5
Q

What is the interpapillary peg?

A

Downward growth of epidermis along crest

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6
Q

describe secondary dermal ridges

A

• Occur in double rows, branched • Thin collagenous, reticular, and elastic fibers

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7
Q

What are dermal papillae

A

Upward projections from each secondary dermal ridge

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8
Q

List the integument functions

A

• Protection from mechanical injury • Prevents dessication • Protects against foreign substances and microorganisms • Protects against UV radiation • Thermoregulation • Regulation of blood pressure (via dermal capillary network) • Excretion of metabolic waste products • Synthesis of provitamin D

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9
Q

Describe thick skin

A

• Occurs only on palms and soles and is hairless • Epidermis varies from 0.4 to 0.6 mm thick. • Displays all five epidermal layers

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10
Q

Describe thin skin

A

• Occurs over rest of body • Epidermis varies from 75 to 150 μmm thick. • Thinnest thin skin is on eyelids • Thickest thin skin is on back • Thicker on extensor surfaces than flexor surfaces • Epidermal layers less distinct and lacking stratum lucidum

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11
Q

What are the layers of the stratified squamous epithelium of the epidermis?

A

• Stratum basale (germinativum) • Stratum spinosum • Stratum granulosum: • Stratum lucidum • Stratum corneum

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12
Q

Which is the deepest layer of the epidermis?

A

stratum basale

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13
Q

Which layer of the epidermis is represented by only a few cells in thin skin?

A

stratum granulosum

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14
Q

Which layer of the epidermis is absent in thin skin?

A

stratum lucidum

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15
Q

Which layer of the epidermis is most superficial?

A

stratum corneum

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16
Q

Describe stratum basale.

A

(germinativum) • Deepest • Columnar to high cuboidal keratinocytes • Keratins 5 and 14 (low-molecular weight keratins) • Single layer of cells • Held together by desmosomes • Hemidesmosomes hold layer to basal lamina • High mitotic activity: • Mitotic activity produces stem cells differentiating keratinocytes. • Affected by chemotherapeutic and radiation treatments

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17
Q

Describe stratum spinosum

A

• Polyhedral-shaped cells (prickle cells) • Keratins 1 and 10 (high molecular weight keratins) • Keratohyalin granules develop • Membrane-coating granules first appear: • Lamellar bodies • Contain lipid, carbohydrate, and hydrolytic enzymes • Tonofibrils • Form intercellular bridges

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18
Q

Describe stratum granulosum

A

• Multilayered • Keratins 2e and 9 • Flattened nucleated keratinocytes • Keratohyalin aggregates: • Fillagrin induces cross-linkage of keratin filaments by disulfide bonds • No limiting membrane • Membrane-coating granules (lamellar bodies) • Acylglucosylceramide → intercellular spaces • Tonofilaments

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19
Q

Describe stratum lucidum

A

• Flat keratinocytes lacking nuclei and organelles • Only found in thick skin • Contains eleiden

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20
Q

Describe stratum corneum

A

• Multilayered (5-50 layers) • Thicker in thick skin • Enucleated, flattened, dead keratinocytes • Cytoplasm replaced by keratin • Cytoplasm contains: • Keratin cross-linked with filaggrin • → cornified cell envelope

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21
Q

List and describe the layers of the cornified cell envelope.

A

• Extracellular: • Multi-lamellar lipid layer covalently linked to involucrine • Intracellular: • Involucrine • Small proline-rich proteins • Loricrin • Fillagrin and keratin complexes

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22
Q

What are the characteristics of the dermis?

A

• Dense fibrous irregular connective tissue layer beneath epidermis • Derived from embryonic mesoderm • Induces development of epidermis and epidermal derivatives • Supports epidermis

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23
Q

What are the characteristics of the hypodermis?

A

• Loose connective tissue that underlies dermis • Corresponds to superficial fascia of gross anatomy • Technically not part of skin • May contain fat cells that can form a thick layer called the panniculus adiposus.

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24
Q

List and describe the two layers of the dermis.

A

• Papillary layer (closest to epidermis): • Loose CT • Separated from epidermis by basal lamina • Network of fine elastic fibers and abundant capillaries • Reticular layer • Dense irregular CT • Includes fibrocytes, macrophages, and adipocytes

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25
Q

What are the cells of the integument?

A

• Keratinocytes • Langerhans cells • Merkel cells • Melanocytes

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26
Q

Describe Merkel cells.

A

• Mechanoreceptors • May also act as diffuse neuroendocrine cells • Usually in stratum germinativum • Contain catecholamine-like granules

27
Q

Describe Langerhans cells.

A

• = dendritic cells • From monocytes • Antigen-presenting cells • Primarily in stratum spinosum • Migrate from epidermis to lymph nodes • Birbeck granules

28
Q

Describe Melanocytes.

A

• Derived from melanoblasts • Do not form desmosome attachments in epidermis • Inject melanin granules into keratinocytes • Pathway for melanin formation

29
Q

What is the pathway for melanin formation?

A

Tyrosine → 3,4-dihydroxyphenylalanine (DOPA) → dopaquinone → melanin

30
Q

What does melanin formation require?

A

tyrosinase

31
Q

Explain the embryonic origins of the epidermis.

A

Epidermis starts as a single layer of ectodermal cells. • Divide during sixth week to form: • Periderm • Sloughs off to form vernix caseosa • Inner cuboidal germinal layer: • continues to proliferate to form adult layers of the epidermis and derivatives: • 10 weeks: fingernails • 12 weeks: hair buds and toenails

32
Q

Explain the embryonic origins of the dermis.

A

Dermis is derived from mesoderm

33
Q

What is A?

A

primary epidermal ridge

34
Q

What is B?

A

interpapillary peg

35
Q

What is C?

A

dermal papilla

36
Q

What is D?

A

secondary dermal ridges

37
Q

What is E?

A

primary dermal ridge

38
Q

What is F?

A

epidermis

39
Q

What is G?

A

dermis

40
Q

What is H?

A

hypodermis (subcutaneous layer)

41
Q

What is A?

A

stratum corneum

42
Q

What is B?

A

stratum granulosum

43
Q

What is C?

A

stratum spinosum

44
Q

What is D?

A

stratum basale

45
Q

What is E?

A

papillary layer of dermis

46
Q

What is F?

A

reticular layer of dermis

47
Q

What is A?

A

stratum corneum

48
Q

What is B?

A

stratum lucidum

49
Q

What is C?

A

stratum granulosum

50
Q

What is D?

A

stratum spinosum

51
Q

What is E?

A

stratum basale

52
Q

What is F?

A

stratum of malpighi

53
Q

What is pictured?

A

tonofilaments in stratum spinosum

54
Q

What is indicated by the star?

A

melanocytes

55
Q

What is pictured?

A

thin skin (scalp)

56
Q

What is pictured?

A

thick skin

57
Q

What is A?

A

stratum corneum

58
Q

What is B?

A

stratum lucidum

59
Q

What is C?

A

stratum granulosum

60
Q

What is D?

A

stratum spinosum

61
Q

What is E?

A

stratum basale

62
Q

What is F?

A

papillary layer

63
Q

What is G?

A

reticular layer

64
Q

What is pictured?

A

integument, dermis