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DSF > DSF Histo of Skin > Flashcards

DSF Histo of Skin Flashcards

1
Q

3 layers of skin

A

Epidermis
Dermis
Hypodermis (subcutis)

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2
Q

Epidermis

A

Keratinized stratified squamous epithelium

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3
Q

Dermis

A

Papillary and Reticular

Loose irregular and dense irregular CT

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4
Q

Hypodermis (subcutis)

A

Loose CT

Shock absorption, insulation, energy reservoir

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5
Q

Thick skin

A 
Soles and palms
Thick layer of epidermis 
Only eccrine glands, no other appendages
Highly innervated for exquisite sensory discrimination
*Have Stratum lucidum
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6
Q

4 cell layers of epidermis (5 in thick skin)

A 
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
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7
Q

4 cell types w/in the epidermal cell layers

A

Keratinocytes
Melanocytes
Langerhans cells
Merkel cells

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8
Q

Keratinocytes

A

Ectodermally-derived cells
Protection from mechanical forces, UV light, water barrier
Specialized apoptosis involved in maturation
Contain majority of skin’s melanin

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9
Q

Melanocytes

A

Produce melanin (oxidation of Tyr (tyrosinase key), released in melanosomes)
Found in stratum basale
Origin: neural crest

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10
Q

Langerhans cells

A

Stratum spinosum
Immune cells of epithelium - can migrate
Lymphocytes, mast cells, macrophages
Dendritic cells (APCs) - adaptive immunity
Derived from bone marrow stem cells (mesoderm)
NO pigment or keratin, can be identified in TEM by folded nuclei
Birbeck granules

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11
Q

Merkel cells

A

Mechanoreceptor cells of epithelium (SB of epidermis)
Also found along basement membrane of hair follicles
Form Merkel corpuscle along w/ underlying nerve processes
Likely neural crest origin
Intimately associated w/ a nerve fiber

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12
Q

Stratum basale

A

Single cuboidal/low columnar layer, attached to BL by hemidesmosomes
Proliferative
Beginning of keratin synthesis - few keratin filaments
Continuous w/ basal layer of appendages
Stains blue due to lots of free ribosomes
Vitamin D production
Melanin present above nucleus (to protect DNA)

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13
Q

Stratum spinosum

A

Stratified and non-uniform
Vitamin D production
“Spinous” processes: cytoplasmic projections/desmosomal attachments
Near basal layer: Proliferative capability, keratin synthesis
Near surface: flatter, larger, more TFs, start of water barrier formation

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14
Q

Keratohyalin granules

A

Stratum granulosum

Contain filaggrin and trichohyalin - involved in aggregation of keratin filaments into tonofibrils (TFs)

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15
Q

Stratum granulosum

A 
1-3 layers thick
No proliferation
Even more keratin filaments bundled into TFs
Lamellar bodies released
Keratohyalin granules
Cells undergo apoptosis
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16
Q

Stratum corneum

A 
Dead cells (no nuclei/organelles)
Keratin matrix
Coated w/ water barrier
Subject to exfoliation/desquamation
*SL in thick skin similar
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17
Q

Psoriasis

A

Accelerated cell proliferation and maturation rate

Characteristic scaly plaques

18
Q

Desquamation of SC

A

Deep layer of SC at neutral pH, becomes acidic superficially - disrupts desmosomal junctions

19
Q

Cytocrine secretion

A

Process by which keratinocytes take up melanin: phagocytose tips of melanocyte dendritic processes
Direct transfer of secretory material from 1 cell to another

20
Q

What is skin pigmentation determined by?

A

Amount, type, and packaging of melanin in epidermis
Partially controlled by melanin breakdown rate (faster in lighter skinned individuals)
(not determined by # of melanocytes)

21
Q

Albinism

A

Hypopigmentation
Defective melanin production
Lack of melanin, due to defect in tyrosinase
Normal # of melanocytes

22
Q

Vitiligo

A

Hypopigmentation

Autoimmune destruction of melanocytes

23
Q

Dermal-Epidermal Junction

A

Epidermis separated from dermis by BL
Rete ridges: epidermis extends down
Dermal papillae: dermis extends up
Gives fingerprint (high density)

24
Q

Bulbous pemphigous

A

Autoimmune disorder w/ antibodies against the hemidesmosomes

Huge blisters occur due to disruption of dermal-epidermal junction

25
Q

Papillary Dermis

A

Superficial loose (areolar) cellular layer/CT

26
Q

Reticular Dermis

A

Lower, denser, less cellular layer/CT

27
Q

Eccrine (sweat) gland

A

Thermoregulation, can be stimulated by stress
Secrete hypotonic fluid that evaporates on skin surface
Found in dermis and superficial hypodermis
Ectodermal in origin
Simple, coiled tubular glands
Glands are pseudostratified epithelium but ducts are 2 layer stratified cuboidal
Merocrine secretion - exocytosis
Controlled by sympathetic NS
Clear, Dark, Myoepithelial cells

28
Q

Apocrine (sweat) gland

A

Secrete fatty acids, proteins, carbs, ammonia, serous fluid, pheromones by budding off of the cytoplasm
Found in axilla, areola, genital region and anus
Ducts discharge into the hair follicle
Found in dermis and upper hypodermis
Merocrine gland - coiled tubular, occasionally branched
Simple cuboidal epithelium
Highly androgen sensitive; not functional until puberty

29
Q

Underarm odor

A

Bacteria process apocrine secretions

30
Q

Sebaceous gland

A

Produce and secrete sebum: highly lipid secretion that lubricates the skin
Resist friction and water barrier
Holocrine gland: secretions made up of disintegrated cells and sebum (apoptosis)
Sebocytes form acini which attach to a common duct
Highly androgen sensitive

31
Q

Hair follicles

A

Hair follicle continuous w/ epidermis (SB)
Sebum deposition moisturizes hair
Hair growth occurs at the bulb, where blood supply and innervation richest
Matrix cells in bulb proliferative
Merkel cells
Melanocytes that contribute to hair color
Associated w/ arrector pili muscle

32
Q

Meissner Corpuscles

A

Encapsulated mechanoreceptors found in dermal papillae
Multiple flattened Schwann cells interspersed by spiraling nerve fibers giving a whorled appearance
Tactile, fine light touch sense

33
Q

Free nerve endings

A

Simple unmyelinated nerves found penetrating the epidermis

34
Q

Pacinian Corpuscles

A

Deep dermis and hypodermis
Sense pressure and vibration
Huge, look like onions in LM

35
Q

Peritrichial nerves

A

Hair base and shaft highly innervated and stimulated by movement of hair

36
Q

Ruffini end organs

A

Stretch receptor found in dermis and joint capsules
Encapsulated fluid-filled structures traversed by collagen
Transmit kinesthetic info (position sense, movement, etc.)

37
Q

Diabetic neuropathy

A

Peripheral nerve damage leads to loss of skin sensation - can make patient unaware of minor injuries
Severe infections can occur if injury goes unnoticed

38
Q

Blood Supply to skin

A 
Blood reaches skin via larger vessels in hypodermis (highly vascularized)
Subpapillary Plexus (gives off capillary loops) and Cutaneous Plexus
39
Q

Arteriovenous anastomoses

A

Shunts in upper dermis
Highly involved in thermoregulation and preservation (shock)
In cold and when intravascular volume low (shock): blood shunted away from skin

40
Q

Protective Features of Skin

A

Mechanical: Stratified squamous epithelium, keratinization, water barrier
Immunoprotection: LC, diffuse lymphatic tissue, dermal lymphatics, macrophages
UV damage: melanin

41
Q

Follicular bulge

A

(Of hair follicle)

Has stem cells for melanocytes and for epidermis

DSF (18 decks)

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