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Histo Exam III > Integument I > Flashcards

Integument I Flashcards

1
Q

Primary Dermal Ridge

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 2 secondary dermal ridges by interpapillary peg
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2
Q

Interpapillary peg

A

Downward growth of epidermis along crest

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3
Q

Secondary dermal ridge

A

Occur in double rows, branched

Thin collagenous, reticular, and elastic fibers

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4
Q

Dermal papillae

A

Upward projections from each secondary dermal ridge

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5
Q

Function of Integument

A

Protection from mechanical injury, prevents desiccation, protects against foreign substances and microorganisms, protects against UV radiation, thermoregulation, regulation of bp (via dermal capillary network), excretion of metabolic waste products, synthesis of provitamin D

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6
Q

Thick skin

A

Occurs only on palms and soles and is hairless
Epidermis varies from 0.4 to 0.6 mm thick
Displays all 5 epidermal layers

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7
Q

Thin Skin

A

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

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8
Q

Dermis

A

Corresponds to lamina propria of a mucous membrane; .5 to 3mm thick

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9
Q

List the epithelial layers of thick skin in the correct order.

A 
Stratum Basale (germinativum) 
Stratum spinosum 
Stratum granulosum 
stratum lucidum 
stratum corneum
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10
Q

Stratum Basale (germinativum)

A

Columnar to high cuboidal keratinocytes - keratins 5 and 14 (low molecular weight)
Only layer with hemidesmosomes. High mitotic activity.

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11
Q

Stratum Spinosum

A

Polyhedral shaped (prickle cells). Keratins 1 and 10 (high molecular weight). Keratohyalin granules, membrane coating granules, and tonofibrils.

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12
Q

Stratum Granulosum

A

Keratins 2e and 9. Flattened nucleated keratinocytes. Tonofilaments.

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13
Q

Stratum Lucidum

A

Flat keratinocytes lacking nuclei and organelles; only found in thick skin. Contains eleiden

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14
Q

Stratum Corneum

A

Thicker in thick skin. Enucleated, flattened, dead keratinocytes. Cytoplasm replaced by keratin. Cornified cell envelope.

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15
Q

Thick skin

A

occurs only in palms and soles and is hairless; epidermis varies from 0.4-0.6 mm thick. Displays all 5 epidermal layers.

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16
Q

Thin skin

A

Epidermis varies from 75-150 um thick. Thicker on extensor surfaces than flexor surfaces. Epidermal layers are less distinct and lacking stratum lucidum.

17
Q

Where is the thinnest thin skin?

A

eyelids

18
Q

Where is the thickest thin skin?

A

back

19
Q

Keratinization

A
  1. lipids are covalently linked to involucrin forming epidermal permeability barrier.
  2. Cornified cell envelope is a specialized structure that reinforces the plasma membrane of keratinocytes when reaching final stage of differentiation. Contains involucrin, small proline rich proteins, and loricrin.
  3. Keratin filaments, aggregated by fillagrin interact w/ the inner side of pm to form cell envelope.
  4. Tight juntions in the stratum granulosum (w/ claudins 1 and 4) are also components of the permeability layer.
20
Q

Dermis Characteristics

A

Dense fibrous irregular CT beneath epidermis; induces development of epidermis and epidermal derivatives - supports epidermis

21
Q

What is dermis derived from?

A

embryonic mesoderm

22
Q

Hypodermis characteristics

A

Loose CT that underlies dermis - corresponds to superficial fascia - technically not part of skin. May contain fat cells that can form panniculus adiposus.

23
Q

2 layers of the dermis

A

papillary and reticular layer

24
Q

Papillary layer (closest to epidermis)

A

Loose CT; separated from epidermis by basal lamina. Network of fine elastic fibers and abundant capillaries.

25
Q

Reticular Layer

A

Dense irregular CT; include fibrocytes, macrophages, and adipocytes.

26
Q

Langerhans cells

A

dendritic cells (antigen presenting cells); from monocytes - primarily in the stratum spinosum - migrate from epidermis to lymph nodes - birbeck granules

27
Q

Merkel Cells

A

Mechanoreceptors; may also act as diffuse neuroendocrine cells; usually in germinativum; contain catecholamine-like granules

28
Q

Melanocytes

A

Derived from melanoblasts; do not form desmosome attachments in epidermis so somewhat mobile; inject melanin granules into keratinocytes; the pathway for melanin formation is tyrosine -> DOPA -> dopaquinone -> malanin.

29
Q

Epidermis starts as?

A

single layer of ectodermal cells

30
Q

What week of embryonic development does the epidermis divide?

A

6th week - forms periderm and inner cuboidal germinal layer

31
Q

What is dermis derived from?

A

mesoderm

Histo Exam III (11 decks)

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