The Ageing Integument (Skin) Flashcards
What is the most obvious sign of ageing
the most obvious
indicator of ageing because the appearance of skin is affected
by internal (glycation & ↓elasticity) and external factors (UV)
Hair also changes colour and falls out
how does the skin provide a first line of defence?
~ it is continually abraded, burned, scalded and injured
~ it is continually attacked by microorganisms
~ it is irradiated by sunlight, particularly U-V light
~ it is exposed to environmental chemicals
What is the main of the integument system?
The cutaneous membrane (skin) composed of:
~ the epidermis (superficial epidermis)
~ the dermis (underlying layer of connective tissue)
What the accessory structures of the integument system?
~ hair follicles and nails (keratin based)
~ multicellular exocrine glands (sebaceous & sweat)
Teeth are also part of the integument system
Wha is the name and location of the part of the integurent system that is shed?
Epidermal keratinocytes in the stratified squamous epithelium
How many layers does the skin have in thin skin?
4 epidermal layers
What and where is EGF?
Epidermal Growth Factor (EGF) is a peptide growth factor
produced by salivary glands and glands in the duodenum
What are the functions of EGF?
To accelerate:
~ division of basal cells in the stratum basale & spinosum
~ production of keratin in differentiating keratinocytes
~ development of the epidermis and its repair after injury
~ stimulating synthetic activity / secretion by epithelial glands
At what age may EGF levels rise?
50+
What effects the colour, thickness and density of hair?
Testosterone, genes and age
What is intrinsic ageing?
Involves genetically determined structural
changes that occur as a natural consequence of ageing
What occurs during intrinsic ageing?
diploid cells (eg fibroblasts) appear to undergo cellular
senesence with finite life-spans in culture (Hayflick limit)
~ hormone changes, particularly decrease oestrogen, and
thyroid hormone promote intrinsic ageing changes
~ generation of reactive oxygen species and free radicals
~ the non-enzymatic Maillard ‘browning’ reaction glycates
amino groups of amino acids and tissue proteins (skin
collagen), forming Amadori Glycation End products (AGE)
What does AGE stand for?
Amadori Glycation End (products)
What do AGEs cause?
An increase cross-linking in collagen and other proteins
adversely affecting their functions
What is skin turgor?
water content of the skin
What is present in young skin and is effected by ageing
• Young skin contains healthy fibrillar collagen bundles and elastin fibres (formed by fibroblasts) giving the dermis strength, stretching resistance and elasticity (proteoglycans) • Intrinsic ageing promotes significant collagen cross -linking and atrophy of dermis collagen & elastin through Maillard, Amadori and Advanced Glycation End product reactions
What is extrinsic ageing?
ageing due to environmental or lifestyle factors
What factors can cause extrinsic ageing?
~ exposure to UV light, particularly in the fair-skinned, due to
living in sunny countries and sun bathing
~ cigarette smoking ages skin in both sexes causing abnormal
elasin (elasosis) and red skin spots (telangiectasia)
~ smoking mainly causes skin damage by decreasing blood
flow in capillaries which causes O2 and nutrient deficiency
~ smoking reduces collagen and elastin in the dermis and
increases wrinkling even more than UV exposure
~ desquamation (skin peeling) can be caused by sunburn and
some hypocholesteremic drugs
~ steroid use can adversely affect skin thickness
What percentage of visible ageing is caused by sunlight?
90%
What type of UV causes genetic mutations and cancer?
UVB and UVA
What is the primary mechanism that UVA causes genetic damage?
Via the generation of free radicals or reactive oxygen features
What reaction does UVA establish?
~ up-regulate matrix metalloproteinases such as collagenase,
gelatinase and stromelysin which destroy collagen, elastin
and other extracellular matrix components
~ impairs repair of collagen, elastin and other components
What is the result of UVA damage over time
~ fibroblasts are damaged impairing dermis maintenance
~ leads to permanent wrinkles, furrows and yellowing
What percentage of skin cancer is caused by chronic UV exposure?
60-90%
How does melanin production change when exposed to chronic UV?
Raised UV light exposure promotes melanin release from the pineal gland which increases melanin production • Melanin containing melanosomes in keratinocytes cluster around the nucleus to protect it from UV light
What are 6 facts regarding Melanin and melanocytes?
• Brown tones in the integument result from synthetic activity of pigment melanocyte cells • Melanocytes sit on the basement membrane in the stratum basale • Their cellular processes extend into the superficial layers • All races have similar numbers of melanocytes (1000 / mm 2 ) but their melanin content varies • Melanin is made from the amino acid tyrosine to absorb U -V light • Carotine, a vitamin A precursor, also accumulates in the skin
Why are small amounts of UV benifical?
Small amounts of U-V light are beneficial because it stimulates epidermal production of vitamin D3 from a 7-dehydrocholesteral ~ only occurs in summer sunlight in the UK • Active vitamin D (1,25(OH)2D3) is a hormone that regulates GI calcium absorption but it also has immunological functions • Vitamin D deficiency causes osteomalacia in adults and rickets in children
What are cleavage lines?
the pattern of collagen and elastic fibres in the skin
Why are cleavage lines clinically significant?
~ a parallel cut will remain closed and heal with little scaring ~ a right -angle cut will pull open by retracting elastic fibres leading to greater scaring • Surgeons cut parallel to cleavage lines
Questions
Q) Describe the ageing related changes in skin and explain how they occur.
Q) How does the skin and other parts of the integument change as a person
ages and what factors can influence the rate of the age-related changes?
Q) Compare the effects of intrinsic (biologically determined) and extrinsic
(environmental or lifestyle) factors that promote ageing of the skin and
special senses, particularly hearing and vision (Summer 2014)
What is the result of vitamin D deficiency?
• Vitamin D deficiency in children, mainly due to lack of sun-light exposure and lack of dietary calcium cause rickets • Bones don’t calcify correctly and bow due to the weight of the body • In older people vitamin D deficiency caused osteopenia
What happens to secretary activity as ageing occurs?
Ageing reduces the secretary activity of the sebaceous glands
Why does skin thin and lose elasticity?
~ collagen fibres give the dermis strength and resist stretch
~ elastic fibres give the dermis elasticity
~ leads to structural damage and permanent wrinkling
