9/ 12 Dennis_PPT_Integument Flashcards

1
Q

Integument

  • Largest organ in the body (15-20% of body weight)
  • Provides: • Protection: physical, chemical, & biological barrier • Sensation & excretion • Thermoregulation • Synthesis of Vitamin D3
  • Epidermis & dermis • Hypodermis = subcutaneous fascia
A
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2
Q

The Epidermis

A
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3
Q

The epidermis composition

A
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4
Q

What are the four main cells in the epidermis?

A

• Keratinocytes • Melanocytes • Merkel cells • Langerhans cells

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5
Q

Two types of skins, what is their distribution?

A
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6
Q

Epidermis: Stratum Basale

  • Single-layer of _____ w/stem cells interspersed
  • Mitotically active, cuboidal/low columnar cells
  • Contains _____
  • Bound apically by via _____
  • Bound basally by _____
A

keratinocytes

melanin

desmosomes

hemidesmosomes

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7
Q

Epidermis: Stratum Spinosum

  • Several cell layers thick
  • Contains ______ with spiny processes
  • Layer thickens with pressure to produce ____ and ___
A

polyhedral keratinocytes

corns & calluses

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8
Q

Epidermis: Stratum Granulosum

  • Thickest layer of _____ portion of epidermis
  • Keratinocytes contain keratohyalin granules
  • Basophilic, cystine- & histadine-rich proteins
  • Precursor to _____ , assembles keratin into bundles
  • Irregularly shaped, variable in size
A

non-keratinized

flaggrin

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9
Q

Epidermis: Stratum Corneum

  • Anucleate cells, lose nucleus & organelles
  • Filled almost entirely with mature ____
  • Plasma membrane coated w/EC layer of lipids → forms ___ barrier of epidermis
A

keratin

water

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10
Q

Epidermis: Stratum Lucidum

  • Subdivision of ____
  • Only well seen in ___ skin
  • Typically poorly stained, translucent band of cells
  • No organelles or nuclei
A

stratum corneum

thick

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11
Q

Keratinocytes

Predominant cell type of the epidermis

  1. Produce keratins, 85% of cells
  2. Participate in the _____
  • Will produce ‘cornified’ cells, full of keratin
  • Undergo keratinization & desquamation
A

epidermal water barrier

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12
Q

Keratinization & Desquamation

Basal cell:

synthesize intermediate (keratin) filaments; grouped into bundles, _____

Spinous cell:

keratin synthesis continues, begin synthesis of keratohyalin granules & glycolipid-containing lamellar bodies

  • Granular cells:
  • Discharge lamellar bodies → water barrier
  • Keratohyalin granules w/filaggrin present
  • Filaggrin further promotes aggregation of keratin filaments (tonofibrils)
  • now cornified cells → keratinized
A

tonofibrils

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13
Q

Epidermal Differentiation & Replacement

  • Epidermal cell replacement is initiated by the division of stem cells in the _____
  • New cells undergo divisions in the stratum basale
  • Move upward as they differentiate into keratinized cells
  • Eventually are lost by exfoliation on skin surface
A

stratum basale

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14
Q

Melanocytes

  • _____-derived, scattered along stratum basale
  • Produce melanin & transfers it to keratinocytes
  • Melanin: pigment protein that protects nuclei from _____

Epidermal-melanin unit: one melanocyte maintains an association with a specific number of keratinocytes ____(ratio)

A

Neural crest

UV radiation

(1:36)

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15
Q

Melanin Production

  • Oxidation of _____ into DOPA (3,4- dihydroxyphenylalanine) by _____
  • DOPA is polymerized into melanin
  • Enzyme is UV sensitive
  • Reactions occur in membrane-bound organelles, ______
  • As more melanin is produced premelanosomes → _____
  • Extend into cell processes
  • Transferred to keratinocytes via ______→ ‘pigment donation’
A

tyrosine and tyrosinase

premelanosomes

melanosome

phagocytosis

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16
Q

Langerhans Cells

  • Antigen-presenting cells (APCs) that provide defense against pathogens
  • Develop from monocyte precursor
  • Antigen is phagocytized & displayed on the cell surface
  • Cell migrates to a nearby lymph node to activate T-lymphocytes
  • Identifiable in _____
  • Pale cytoplasm with long processes
A

stratum spinosum

17
Q

Merkel Cells

  • Epidermal cells that function in _____
  • Provide acute sensory perception (fingertips)
  • Reside in the ______
  • Associated with nerve endings
  • Merkel cell carcinoma (MCC): • Rare, but highly aggressive form of skin cancer • Merkel cells undergo uncontrolled proliferation
A

cutaneous sensation

stratum basale

18
Q

Dermal-Epidermal Junction

  • Uneven boundary except in the thinnest skin
  • Finger-like _____, project into epidermis
  • Complemented by epidermal protrusions, ______
  • Increased in size at sites of mechanical stress
  • Hemidesmosomes provide tight interface
  • Focal adhesions are also present
A

dermal papillae

epidermal (rete) ridges

19
Q

Layers of the Dermis

what are the two layers? Which layer has the langer’s lines?

A
  • Papillary layer:
  • Loose CT immediately beneath epidermis • Thinner collagen fibers, elastic fibers • Includes dermal papilla & ridges • Vasculature & nerve endings

• Reticular layer:

• Deep to papillary layer • Thicker & less cellular • Thick, irregular bundles of type I collagen & coarse elastic fibers • Form regular lines of tension, Langer’s lines

20
Q

Hypodermis (Subcutaneous Fascia)

  • Adipose tissue (panniculus adiposus)
  • Varies in thickness/body region
  • Energy storage site, insulation
  • Arrector pili muscles → ______
A

hair follicles

21
Q

integument summary

A
22
Q

Meissner’s Corpuscle

  • Touch receptors responsive to____
  • Tapered cylinders oriented _____ to the skin surface
  • Present in the _____ just beneath the epidermis
A

low-frequency stimuli

perpendicular

dermal papillae

23
Q

Pacinian Corpuscle

  • Large, ovoid structures found in the deeper ____and____
  • Fingertips, joints, periosteum, & internal organs
  • Detects ____or____
  • Myelinated nerve ending surrounded by a capsule structure
A

dermis and hypodermis

pressure or vibration

24
Q

Free Nerve Endings

  • Terminate in the _____
  • “Free” in that they lack ___
  • Modalities: fine touch, heat, cold, & pain
  • Free dermal endings surround most hair follicles
  • Sensitive to ____ movement
  • Serve as _______
A

stratum granulosum

CT

hair

mechanoreceptors

25
Q

what are three types of glands? and their mechanism?

A
  1. merocrine -Secretion is delivered in membrane-bound vesicles to apical surface & undergo exocytosis
  2. holocrine - Secretion accumulates w/in cell → apotosis Secretion & cell debris are released
  3. apocrine - Release of the apical portion of the cell, surrounded by cytoplasm w/in a plasma membrane
26
Q

Sebaceous Glands

  • Several glands per follicle
  • Abundant on ___and____
  • Produce a lipid mixture, ___ via ____ secretion
  • Waxy mix of triglycerides & cholesterol
  • Lubricates & softens skin
  • Waterproofs skin
  • Sebum discharged into the infundibulum (hair follicle), forming _____canal
A

face & scalp

sebum/holocrine

pilosebaceous

27
Q

Sweat (Sudoriferous) Glands

  • Classified by structure & nature of their secretion
  • Eccrine (merocrine) sweat glands:
  • Coiled glands distributed over the entire body surface
  • Except lips & external genitalia
  • Apocrine sweat glands:
  • Axilla, areola, & nipple, skin around the anus, external genitalia
  • Ceruminous glands of ear canal
A
28
Q

Eccrine Sweat Glands

  • Simple, coiled glands found extensively throughout skin
  • Duct is _____
  • _____cells facilitate expulsion of secretions
  • Temperature regulation via cooling
  • Evaporation of H2O from sweat on body surface

Sweat components:

  • Water, salt, ammonia, uric acid & mucinogen granules
  • Subject to cholinergic regulation
A

cuboidal stratified

Myoepithelial

29
Q

Apocrine Sweat Glands

  • Large-lumen, tubular glands
  • Duct is ______
  • Use ____secretion
  • Protein, carbohydrate, & ammoniarich secretion
  • Odorless until mixed w/bacteria
  • Myoepithelial cells facilitate expulsion of secretions
  • Functional & puberty, subject to adrenergic regulation
A

stratified cuboidal

merocrine

30
Q

Hair Follicles & Hair

  • ______: extends from surface opening to the opening of its sebaceous gland
  • _____: near insertion of the arrector pili m, contains epidermal stem cells
  • Bulb: expanded inferior segment, Invaginated by vascularized loose CT, the _____
  • Hair matrix: consists matrix cells Cells rapid divide/differentiate, accounts for hair growth
A

Infundibulum

Follicular bulge

dermal papilla

31
Q

Hair Shaft
what are the three main domains?

A
  • Medulla: central part of the shaft
  • Column of large, loosely connected keratinized cells
  • Cortex: largest layer, located outside the medulla
  • Cells filled with hard keratin intermediate filaments
  • Cuticle: outermost layer
  • Several layers of overlapping, keratinized squamous cells
  • Vellus vs. terminal hair
32
Q

Nails

  • Highly keratinized cells on a bed of epidermis (nail bed)
  • _____: the most proximal region, covers the nail matrix
  • _____: stem cells divide & form keratinocytes
  • Nail plate remains attached to nail bed
  • Pushed forward by continuous growth
  • ____: crescent-shaped white area near the nail matrix
  • ____: extension of skin covering nail root
A

Nail root

Nail matrix

Lunula

Cuticle