These changes affect
the dermis in particular and result from changes in the chemical structure
of the collagen and elastin, and to the quality and quantity of proteins
and natural acids in the skin.
Understanding the changes that occur in the
cells and layers of the skin with intrinsic and extrinsic aging will
help us to understand why skin looks as it does, and how we can protect
or alter this appearance. It also allows us to understand why it is
so important to protect the skin of children and to educate them in
skin care.
In intrinsic aging, the skin becomes
thinner and loses much of its elasticity, while the normal expression
lines deepen. The boundary between the epidermis and the dermis |
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is flattened, and the dermis starts to wither (atrophy). The number
of blood vessels in the dermis begins to fall. At the same time
the hair often loses its color, and within the skin there are fewer
hair follicles and fewer sweat glands. The collagen, elastin and
ground substance also decrease in amount, but the proteins remain
in a reasonably stable state.
In extrinsic aging the epidermis
thickens. The amounts of collagen and elastin increase, but the
structures of these proteins become disorganised. Almost all of
this is due to effects of radiation from the sun, known as photodamage.
- 'Intrinsic aging' happens inevitably.
- 'Extrinsic aging' is due to outside factors that have affected
the skin.
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