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Immunology > 44-Skin as a Protective Barrier > Flashcards

44-Skin as a Protective Barrier Flashcards

1
Q

Functions of skin

A 
Fluid and electrolyte homeostasis
Protect from toxic substances
Protect from trauma
Thermoregulation
Metabolic functions 
Protect from infection
Protect from UV light
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2
Q

What is keratinization

A

Process of cell maturation to form flexible protective barrier

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3
Q

Characteristics of keratinization

A 
Genetically programmed
In post mitosis keratinocytes
Morphologic changes
Regulated by extrinsic and intrinsic factors
Vulnerable to alteration
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4
Q

The steps of epidermal differentiation

A

alterations of plasma membrane antigens and receptors
Degradation of organelles
Cellular dehydration

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5
Q

What is the stratum corneum

A

semipermeable barrier to water and electrolytes

Protects internal environment

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6
Q

structure of stratum corneum

A

bicompartment of hydrophilic protein cells (corneocytes) surrounded by hydrophobic intercellular lipid matrix

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7
Q

What are corneocytes

A

metabolically inert

enucleated cells formed from keratinocytes

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8
Q

What is the cornified envelope

A

Component of corneocytes, cross linked proteins catalyzed by transglutaminase 1
loricrin, involucrin, keratolinin

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9
Q

What are the proteins in the cornified envelope

A

loricrin, involucrin,keratolinin

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10
Q

What catalyzes the cornified envelope cross linked proteins

A

transglutaminase 1

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11
Q

What surrounds the cornified envelope

A

lipid envelope

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12
Q

What makes the intercellular lipid matrix

A

lamellar granules from keratinocytes organelles

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13
Q

Where are lamellar granules found

A

Between the granular layer and the stratum corneum

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14
Q

What do the lamellar granules do

A

Fuse with membrane and discharge lipid contents

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15
Q

What are the major membrane lipids of stratum corneum

A

ceramides

Impermeable to water

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16
Q

What do epidermal lipids do

A

form cement to hold corneocytes together

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17
Q

what is in lamellar granules/Orland bodies

A

lipids

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18
Q

What is in keratohyalin granules

A

protiens

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19
Q

Where are lamellar/Odland found

A

Upper spinous, layer, granular cornified layer interface

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20
Q

Where are keratohyalin granules found

A

Upper spinous layer,

Granular and cornified layers

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21
Q

Do lamellar/Odland have membranes

A

Yes, membrane bound

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22
Q

Do keratohyalin have membranes

A

No, not membrane bound

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23
Q

What is the function of lamellar/ Odland

A

deliver precursors of corneum lipids

Lipids accumulate in lamellar granules and fuse with plasma membrane to exocytose lipid to intercellular space

24
Q

What is the function of keratohyalin granules

A

deliver free amino acids to corneum (filaggrin monomers)

Conversion of profilaggrin to filaggrin

25
Q

What cannot pass through corneum

A

Polar or large molecules (MW > 800-1000)

26
Q

How does corneum protect from trauma

A 
Strong stratum corneum
Highly resistant cornified envelope
corneocytes are interdigitated
desmosomes
corneum is elastic
Low conductivity-protection from electrical and thermal damage
Nerve sensations
27
Q

What is core body temp

A

37

28
Q

What temps can skin vary between without damage

A

20-40

29
Q

How does body thermoregulate

A

Blood vessel and eccrin glands

30
Q

What does the body do in cold environment

A

Use sympathetic to contract vessel, decrease peripheral flow and conserve central body heat

31
Q

What does body do in hot environment

A

Decrease sympathetic and dilate blood cells for heat loss

32
Q

What controls eccrine sweat gland

A

Hypothalamus for cooling

33
Q

Production of active vita. d

A

7 dehydrocholesterol converted to cholecalciferol in skin using UV light
Converted to 1, 25 dihydroxycholecalciferol in liver and kidney

34
Q

What is the function of vita. d

A

Increase Ca absorption from GI

Increase CA reabsorption from kidneys

35
Q

What are the structural mechanisms to protect from infection

A

Intact stratum corneum
Dryness to stop growth
desquamation to remove microbes

36
Q

What do Langerhans cells do

A

Recognize foreign antigen and present to t cell to start immune response
Delayed hypersensitivity reactions
Interact with keratinocytes to secrete cytokines

37
Q

What inflammatory cells are found in the dermis

A

lympho, histo, neutron, eosino, mast

38
Q

What do sebaceous glands do

A

Secrete protein and lipids for antimicrobial

39
Q

What does UV light cause

A

Sunburn, chronic photodamage, carcinogens

40
Q

UVC

A

Shortest, absorbed by ozon

41
Q

UVB

A

Middle, causes burns

42
Q

UVA

A

Longest, causes tans

43
Q

What are chromophores

A

Molecules path absorb radiant energy, usually in low energy state and get activated.
To return to ground state, must release absorbed energy

44
Q

Ways for chromophore to release absorbed energy

A

Photochemical reaction
Photosensitized reaction
Release as heat

45
Q

What is a photochemical reaction

A

Undergo chemical change to form photoproduct (DNA pyramidine)

46
Q

What is a photosensitized reaction

A

Transfer of energy to another molecule

47
Q

What are mediators of erythema

A

Histamine, prostaglandins, cytokines, lysosomal enzymes

48
Q

What is tanning

A

A response to UV induced skin damage

49
Q

What does UV light do to melanocytes

A

Increase number, size and dendrite branching

Increase melanin and malanosome synthesis

50
Q

What is dermatoheliosis

A

Chronic photodamage

51
Q

Characteristics of chronic photodamage

A

(dermatoheliosis)- aged appearance, wrinkles, telangiectasias

52
Q

What are telangiectasias

A

Dilated blood vessels

53
Q

What acts as a photoprotection

A

Melanin

by block, scatter, and absorb UV light, trap free radicals

54
Q

Who is more at risk for skin cancer

A

Fair skin

55
Q

What percent of UVB and UVA penetrate to basal layer

A

5-10 of UVB

50 of UVA

56
Q

Facts about sunscreen

A

Do not block all UV, use higher SPF
Apply generous amount every few hours
Many do not block UVA

57
Q

What ingredients block UVA

A

Parasol 1789, titanium dioxide, zinc oxide

Immunology (19 decks)

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