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Aging Essay

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Intrinsic skin aging results from the normal chronological processes that affects all organs during aging and is influenced by numerous factors that change during aging such as decreases in hormonal production [42]. It is well established that decreases in hormonal production results in a loss of moisture in aging skin, with concomitant reduction in elasticity, epidermal atrophy, increased collagen degradation and wrinkling of the skin [43 44]. Adult skin progressively thins at a rate that accelerates with age and all components of skin appear to decrease in thickness with age [45, 46]. The changes that occur to different layers of the skin are depicted in Figure 3.

Hyaluronic acid levels are high in the fetal circulation and fall …show more content…

Because HA homeostasis is maintained at fairly constant levels throughout life, it is reasonable that decreases in HA synthesis are accompanied by concomitant decreases in HA degradation.

There are differing observations about whether the total amount of HA remains constant in the skin with aging. In contrast to earlier in vitro [54, 55] and in vivo [56, 57] reports, recent studies report that the total amount of HA in the skin remains constant with aging. One consistent observation is that the amount of epidermal HA decreases with aging and is almost absent in aging skin [58]. Decreases in epidermal HA levels appear to be countered by an increase in the amount of HA in the basal layer of the epidermis and the papillary layer of the dermis [51]. When skin samples from 11 and 14 year olds were compared to 21 and 22-year-old skin samples, a decrease in HA expression in the stratum spinosum and increase in papillary dermis HA expression was observed. This trend continued when comparing these samples to 49, 50 and 70-year-old skin samples. No HA was observed in the stratum spinosum in the two skin samples from senescent skin from 81 and 89-year-old skin donors [58]. HA expression from 29-year-old and 81-year-old skin is shown in Figure 4. In summary, there appears to be a shift of HA expression from the epidermal layers towards lower dermal layers that occurs with aging.

HA present in skin

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