44-Skin as a Protective Barrier Flashcards Preview

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Flashcards in 44-Skin as a Protective Barrier Deck (57)
1

Functions of skin

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

2

What is keratinization

Process of cell maturation to form flexible protective barrier

3

Characteristics of keratinization

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

4

The steps of epidermal differentiation

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

5

What is the stratum corneum

semipermeable barrier to water and electrolytes
Protects internal environment

6

structure of stratum corneum

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

7

What are corneocytes

metabolically inert
enucleated cells formed from keratinocytes

8

What is the cornified envelope

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

9

What are the proteins in the cornified envelope

loricrin, involucrin,keratolinin

10

What catalyzes the cornified envelope cross linked proteins

transglutaminase 1

11

What surrounds the cornified envelope

lipid envelope

12

What makes the intercellular lipid matrix

lamellar granules from keratinocytes organelles

13

Where are lamellar granules found

Between the granular layer and the stratum corneum

14

What do the lamellar granules do

Fuse with membrane and discharge lipid contents

15

What are the major membrane lipids of stratum corneum

ceramides
Impermeable to water

16

What do epidermal lipids do

form cement to hold corneocytes together

17

what is in lamellar granules/Orland bodies

lipids

18

What is in keratohyalin granules

protiens

19

Where are lamellar/Odland found

Upper spinous, layer, granular cornified layer interface

20

Where are keratohyalin granules found

Upper spinous layer,
Granular and cornified layers

21

Do lamellar/Odland have membranes

Yes, membrane bound

22

Do keratohyalin have membranes

No, not membrane bound

23

What is the function of lamellar/ Odland

deliver precursors of corneum lipids
Lipids accumulate in lamellar granules and fuse with plasma membrane to exocytose lipid to intercellular space

24

What is the function of keratohyalin granules

deliver free amino acids to corneum (filaggrin monomers)
Conversion of profilaggrin to filaggrin

25

What cannot pass through corneum

Polar or large molecules (MW > 800-1000)

26

How does corneum protect from trauma

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

What is core body temp

37

28

What temps can skin vary between without damage

20-40

29

How does body thermoregulate

Blood vessel and eccrin glands

30

What does the body do in cold environment

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

31

What does body do in hot environment

Decrease sympathetic and dilate blood cells for heat loss

32

What controls eccrine sweat gland

Hypothalamus for cooling

33

Production of active vita. d

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

34

What is the function of vita. d

Increase Ca absorption from GI
Increase CA reabsorption from kidneys

35

What are the structural mechanisms to protect from infection

Intact stratum corneum
Dryness to stop growth
desquamation to remove microbes

36

What do Langerhans cells do

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

37

What inflammatory cells are found in the dermis

lympho, histo, neutron, eosino, mast

38

What do sebaceous glands do

Secrete protein and lipids for antimicrobial

39

What does UV light cause

Sunburn, chronic photodamage, carcinogens

40

UVC

Shortest, absorbed by ozon

41

UVB

Middle, causes burns

42

UVA

Longest, causes tans

43

What are chromophores

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

44

Ways for chromophore to release absorbed energy

Photochemical reaction
Photosensitized reaction
Release as heat

45

What is a photochemical reaction

Undergo chemical change to form photoproduct (DNA pyramidine)

46

What is a photosensitized reaction

Transfer of energy to another molecule

47

What are mediators of erythema

Histamine, prostaglandins, cytokines, lysosomal enzymes

48

What is tanning

A response to UV induced skin damage

49

What does UV light do to melanocytes

Increase number, size and dendrite branching
Increase melanin and malanosome synthesis

50

What is dermatoheliosis

Chronic photodamage

51

Characteristics of chronic photodamage

(dermatoheliosis)- aged appearance, wrinkles, telangiectasias

52

What are telangiectasias

Dilated blood vessels

53

What acts as a photoprotection

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

54

Who is more at risk for skin cancer

Fair skin

55

What percent of UVB and UVA penetrate to basal layer

5-10 of UVB
50 of UVA

56

Facts about sunscreen

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

57

What ingredients block UVA

Parasol 1789, titanium dioxide, zinc oxide