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PR2202 > L15: Sunscreens > Flashcards

L15: Sunscreens Flashcards

1
Q

What is the main electromagnetic wave concerned with skin damage from sunlight exposure?

A

UV light, specifically UV-A and UV-B

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2
Q

Which is the main cause of sunburn and skin cancer, UV-A or UV-B?

A

UV-B

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3
Q

Which penetrate deeper into the skin, UV-A or UV-B?

A

UV-A

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4
Q

Which does more damage to the skin, UV-A or UV-B?

A

UV-A

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5
Q

What are some of the natural protective mechanisms against ultraviolet light present in the stratum corneum?

A
  • Scattering and reflection of UV radiation by corneocytes

- Endogenous body antioxidants (eg. carotenoids, urocanic acid and superoxide dismutase)

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6
Q

Epidermis absorbs radiation of what wavelength?

A

< 320nm

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7
Q

Which layer of the skin absorbs radiation wavelengths of > 320nm?

A

Dermis

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8
Q

How does tanned skin arise from exposure to ultraviolet rays?

A

UV rays are absorbed by melanin, causing it to oxidize and result in tanned skin.

This process is called delayed tanning or persistent pigment darkening

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9
Q

What is skin colour determined by?

A
  • Mix of carotenoids
  • Different types of melanin
  • the way that melanin is packaged and distributed in melanosomes
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10
Q

What is the relationship between skin pigmentation and incidence of sun-induced skin cancers?

A

Inverse relationship

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11
Q

What causes albino phenotype?

A

Defective melanocytes, thus unable to produce melanin for photo-protection

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12
Q

What are the two types of albinos?

A

Constitutive and facultative

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13
Q

What is skin cancer caused by?

A

Long-term exposure to the sun and bad sunburns

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14
Q

What kind of eye damage can the sun do?

A
  • Cataracts
  • Photokeratitis
  • Pterygium
  • Cancer of the eye
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15
Q

What are the 3 main types of skin cancer?

A
  • Basal cell carcinoma
  • Squamous cell carcinoma
  • Melanoma
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16
Q

Can exposure to sun cause allergies?

A

Yes

17
Q

What are the two main types of sunscreens?

A

Organic and inorganic

18
Q

What is the MOA of organic sunscreens?

A

Absorb UV radiation like melanin and transform it into heat

19
Q

Organic sunscreens can offer sufficient protection with just one application throughout the day. True or False?

A

False. it must be frequently reapplied to maintain protection from the sun.

20
Q

What is the MOA of inorganic sunscreens?

A

Reflect or scatter UV radiation, absorbing little energy

21
Q

Inorganic sunscreens should be frequently reapplied to confer sufficient protection against the sun. True or False?

A

False. Their effect lasts longer and do not require frequent reapplication.

22
Q

What are some examples of UVA organic sunscreens?

A
  • Benzophenones
  • Avobenzone
  • Anthranilates
23
Q

Salicylate is a type of UVB organic sunscreen. True or False?

A

True.

24
Q

Cinnamate is a type of UVA inorganic sunscreen. True or False?

A

False. It is a UVB organic sunscreen

25
Q

What are some examples of inorganic sunscreens?

A
  • Titanium oxide

- Zinc oxide

26
Q

What are the advantages of employing nanoparticles in sunscreens?

A
  • Transparent

- Aggregation

27
Q

What are some disadvantages of employing nanoparticles in sunscreens?

A
  • May penetrate into the deeper layers of the skin; may confer side effects that are yet known
  • Toxic to the environment (as it kills plankton)
28
Q

What does Minimal Erythema Dose (MED) refer to?

A

Minimum UV radiation dose that produces clearly emarginated erythema in the irradiated site, given as a single exposure

TLDR: minimum UV radiation dose to cause sunburn

29
Q

What is the formula for Sun Protection Factor?

A

MED of protected skin / MED of unprotected skin

or

Time to produce erythema on protected skin / Time to produce erythema on unprotected skin

30
Q

What does an SPF of 6 mean?

A

It means that it takes 6 times longer for skin protected with this sunscreen to develop sunburn than normal

31
Q

How much sunscreen should be applied?

A

Apply 2mg/cm^2 of sunscreen

For an average-sized person, this is equivalent to a shot glass

32
Q

What are some disadvantages of water-resistant sunscreens?

A
  • Water dissolves the oily sunscreen film by interacting with the emulsifier
  • Rubbing removal
  • Physical degradation
33
Q

What kind of ingredients should after-sun products contain?

A
  • Moisturizer
  • Anti-inflammatory ingredients
  • Cooling compounds: Menthol, camphor
  • Antioxidants: Vit E, Vit C, carotenoids, coenzyme Q10
  • Others: Extra virgin olive oil, Aloe, Shea butter
34
Q

What are the protective measures against UV radiation?

A
  • Avoid the sun
  • Use sunscreens
  • Wear a hat
  • Cover up
  • Wear sunglasses
  • Avoid artificial tanning
35
Q

What is the upper SPF limit?

A

50

36
Q

Why is it not recommended for sunscreens to have SPF of > 30?

A

It offers little additional benefit and may unnecessarily expose users to dangerous levels of chemicals

37
Q

What additional information should water-resistant or sweat-resistant sunscreens provide?

A

SPF for both before and after being exposed to water or sweat

38
Q

Any tanning product that doesn’t contain a sunscreen would have to state on the label that the product does not contain a sunscreen. True or False?

A

True

PR2202 (18 decks)

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