16. 1. The primary & the most important
determinant of variability in human skin
color
1. Amount
2. Density and
3. distribution
2. Melanin has a dark brown/purple/black
color
1. It is intensified by denser compaction
17. CONSTITUTIVE
1. Genetically determined
2. Irrespective of sun exposure
FACULTATIVE
Changes in response to sun
exposure
18. 1. Sunlight has profound effects on the skin
2. Ultraviolet (UV) light can cause a lot of
skin reactions and other problems.
19. 1. UVA penetrates window glass
2. UVA causes immediate and delayed tanning
3. It is constant throughout the day and throughout the year
1. UVB produces the most harmful effects and is greatest
during the summer
2. Snow and ice reflect UVB radiation
3. It produces tanning more efficiently than does UVA
1. UVC is almost completely absorbed by the ozone layer
20.
21. signs of aging may start by age 30 to 35
Fine wrinkles that resemble
crumpled cigarette paper
These shallow wrinkles
disappear by stretching
Reduction in collagen, fat & elastic fibers
26. Protection of the DNA from under going
damage due to the UV Radiation
coming from the Sun
27. A tan protects the body from photo injury
Tanning occurs in 2 stages
1st stage
1. Immediate pigment darkening
2. Caused primarily by UVA
3. Fades rapidly
2nd Stage
1. If exposure to sun is continuous and prolonged
2. synthesis of new melanin.
3. Will appear only after 72 hrs.
4. Caused primarily by UVB
28. SUNBURN
1. Intense Redness
2. Some times blisters
Skin burns because it does not tan
29. Type Characteristic Examples
I Always burns easily, never Irish extraction; often blue eyes,
tans red hair, freckles
II Burns easily, tans slightly Fair-skinned individuals; often
have blond hair; many whites
III Sometimes burns, then tans Mediterranean's and some
gradually and moderately Hispanics
IV Burns minimally, always Darker Hispanics and Asians
tans well
V Burns rarely, tans deeply Middle Easterners, Asians, some
blacks
VI Almost never burns, deeply Some blacks
pigmented
Dermatol Clin 24(1):9-17, 2006
35. Amount of UVR required to cause
sunburn when sunscreen is applied
SPF =
Amount of UVR required to cause
sunburn when sunscreen is NOT applied
36. Type Characteristic Suggested SPF
Routine Outdoor
day activity
I Always burns easily, never tans 15 25-30
II Burns easily, tans slightly 12-15 25-30
III Sometimes burns, then tans
gradually and moderately 8-10 15
IV Burns minimally, always tans well
6-8 15
V Burns rarely, tans deeply
6-8 15
VI Almost never burns, deeply
pigmented 6-8 15
Dermatol Clin 24(1):9-17, 2006
37. I leave the decision to you
But before you take the decision,
Just one more thing
38. Vitamin D is formed in the skin through
the action of the sun
Strict sun protection can cause vitamin D
deficiency
Vitamin D deficiency may induce various types of
1. Cancer
2. Bone diseases
3. Hypertension, (blood pressure) and
4. Heart disease