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Dermatology > Microanatomy of the Skin > Flashcards

Microanatomy of the Skin Flashcards

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Dermatology Board Prep flashcards
1
Q

Primary functions of skin?

A 
Barrier (retain water, prevent infection, absorb UV)
Production of Vitamin D
Thermoregulation
Secretion
Sensation
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2
Q

Ectoderm: components

A

Epithelial: epidermis, pilosebaceous units, eccrine glands, apocrine glands
Neuroectoderm: melanocytes, nerves, Merkel cells

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3
Q

Mesoderm components

A
  1. Hematopoietic: mast cells, MØ, Langerhan’s cells, lymphocytes
  2. Mesenchymal: fibroblasts (dermis), endothelial and pericytic cells (vessels), subcutaneous fat (adipocytes)
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4
Q

Epidermis: layers

A
  1. stratum basalis
  2. stratum spinosum
  3. stratum granulosum
  4. stratum corneum
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5
Q

Normal transit time from basalis layer to top of skin?

A

28 days

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6
Q

Stratum basalis

A
  • cells attach to basement membrane via hemidesmosomes
  • basal layer: stem-like cells, highest proliferative index in unremarkable skin
  • cells with perinuclear melanosomal cap protects from UV damage
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7
Q

Stratum spinosum

A
  • cells initiate terminal differentiation
  • thickest part of dermis
  • DESMOSOMES and ADHERINS junctions are prominent and give epidermis strength
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8
Q

Stratum granulosum

A
  • Keratohyaline granules (contain flaggrin-cross link keratin filaments)
  • organelles, nuclei disappear
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9
Q

Stratum corneum

A
  • cell becomes network of cross-linked proteins and lipids

- secretion of protein-bound lipids (ODLAND BODIES) into intercellular space to enhance barrier

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10
Q

How many types of keratins are there? What are they?

A

2; Type 1 (acidic) and Type 2 (basic)

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11
Q

What are keratins?

A

1’ structural protein of keratinocytes, critical for barrier function

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12
Q

What structures give the epidermis strength and integrity?

A

Desmosomes

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13
Q

Basement Membrane

A

Organized structure of proteins forming bridge between dermis and epidermis; comprised of

  1. Lamina lucida (laminin, ladinin)
  2. Lamina densa (nidogen, Type IV collagen)
  3. Sub-lamina densa (anchoring fibrils, type VII collagen)
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14
Q

Rete

A

Downward invaginations that interdigitate with dermal papilla to form structure that provides mechanical integrity and immune surveillance

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15
Q

Functions of Rete

A
  1. Bring vasculature in close proximity to epidermis
  2. Facilitate trafficking of immune cells
  3. Lost during aging –> fragility
  4. RESTORE LATERAL FORCES in the skin
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16
Q

Melanocytes

A

NEURAL CREST-DERIVED, mature upon reaching epidermis, transfer melanosomes to keratinoytes

17
Q

Appearance of melanocytes on H&E

A

inconspicuous; may see brown nest on top (melanosomal cap)

18
Q

Melanocyte stain?

A

MART-1 (see dendritic tree of melanocytes)

19
Q

Langerhan’s Cells

A

BONE MARROW-DERIVED, professional APCs, usually located in stratum spinosum

20
Q

Role of Langerhan’s Cells

A
  1. Prevent infection and neoplasia
  2. Mediate allergic contact dermatitis
  3. Traffic between epidermis and lymph nodes
21
Q

Langerhan’s Cells - stain?

A

CD1a

22
Q

Merkel Cell

A

NEUROEPITHELIAL ORIGIN - likely from epidermis

23
Q

Merkel Cell - function

A

sensation (likely)

24
Q

Merkel Cell - stain

A

CK 20

25
Q

Dermis ECM

A
  • COLLAGENS provide durability, strength
  • ELASTINS - elasticity, tightness
  • MUCOPOLYSACCHARIDES - hyaluronic acid - resilience, fullness
26
Q

Skin appendages in dermis?

A

Pilosebaceous unit, eccrine gland, apocrine gland (axilla, groin)

27
Q

Where is eccrine gland located? What does it do?

A

Junction of dermis and subcutaneous fat, empties to skin

  • 2-4 million
  • involved in thermoregulation, sweat production
  • most abundant on foot, least on back
  • consists of secretory cell and duct
  • duct lined by MYOEPITHELIAL CELLS that help push sweat to skin surface
28
Q

What about apocrine glands?

A

A little bit bigger than sweat glands, drain into hair follicle

  • anogenital, areolae, eyelid, scalp, abdomen, EAM
  • glands in lower dermis, subcutis
  • enclosed by discontinuous myoepithelial cells that contract 2’ to alpha-adrenergic agonists
  • originate from INFUNDIBULAR portion of hair follicle, found only on hairy skin
  • not responsive to heat
29
Q

…and sebaceous glands?

A

Near the skin surface, drain into hair follicle

  • produce SEBUM (fatty)
  • flows onto skin surface & mixes w/lipids
30
Q

Three cell types in eccrine glands?

A
  1. Dark cell (CFTR, Cl- transporter)
  2. Clear cell (secrete water, electrolytes)
  3. Myoepithelial cells (contract)
31
Q

What are apocrine gland secretions?

A

-mixture of electrolytes & proteins (albumin, globulin, hexosamine, mucoprotein)

32
Q

Axillary odor…what gives?

A

Odor produced by bacteria acting on lipids in APOCRINE gland secretions

33
Q

Myoepithlial cell marker?

A

Anti-SMA (smooth muscle actin)

34
Q

Cells within dermis

A
  1. FIBROBLASTS (produce collagen, elastin, mucopolysaccharides)
  2. SMOOTH MUSCLE CELLS (pilar muscles)
  3. ENDOTHELIUM (vascular, lymphatic)
  4. MAST CELLS
  5. NERVE CELLS
35
Q

Mast Cell

A
  • hypersensitivity
  • located near vessels, nerves, lymphatics
  • granules contain TRYPTASE, CHYMASE
  • activated through Fc ER1
  • SCF (c-Kit) agonist
36
Q

Subcutaneous Adipose Tissue

A
  • composed of adipocytes

- functions: INSULATION, SHOCK ABSORPTION, ENERGY STORAGE, METABOLISM

Dermatology (3 decks)

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