Transcript Ageing Skin
Ageing
Skin
Dr Bill Revell
AGEING
Process of progressive generalised impairment of function
Resulting in an increasing age- specific death rate
Tom Kirkwood
Ageing
Results from accumulation of un-repaired damage of somatic cells and tissues
Progressive failure of maintenance mechanisms to respond to environmental attrition
Free radical damage may offer a unifying theory for cellular senescence, underlying human ageing and age related diseases
Deteriorating Tissue Function
Associated with change in cell functioning
+/- Change in cell turnover when old or defective cells are not replaced
age related changes in metabolic functions
Reduced oxidative phosphorylation by mitochondria
Diminished synthesis of structural, enzymatic and regulatory proteins
Decreased capacity for uptake of nutrients
Increased DNA damage and diminished repair of chromosomal damage
Accumulation of oxidative damage in proteins and lipids (eg lipofuscin pigment)
Accumulation of advanced glycosylation end products
Morphological alterations
Irregular and abnormally lobed nuclei
Swollen, pleomorphic and vacuolated mitochondria
Decreased endoplasmic reticulum
Distorted Golgi apparatus
Ageing skin; a preamble……….
Huge efforts to hide and disguise
Gerontological discussion has little to do with morbidity or mortality; very few patients die of old skin, or succumb to skin failure
Importance is primarily psychological
Emotional impact of skin ageing should not be underestimated
Ageing skin
Wrinkled
Most pronounced on sun exposed parts
Age or liver spots
Loss of hair
Sagging facial muscles
Increased fragility
Skin contains less collagen and elastin; abnormal
changes to collagen and elastin
Thinner; less elastin; less collagen
Abnormal elastin and collagen
Wrinkling; most pronounced on sun exposed skin
Collagen Cross Links
Eg intermolecular cross links between lysine residues in adjacent collagen helices
Non-reducible cross links increase with age
Arise as a side effect of free radical damage
A
dvanced
G
lycosylation
E
nd Products
Post-translational modification of collagen by sugar (AGE products)
Non-enzymatic attachment of glucose to proteins
Formation of irreversible cross links
Structural age changes in skin
dermis
Age related changes – “normal” ageing
Epidermis
Epidermis thinner
Increased “scaling off”
Declining rate of cell division
Decrease in dermal papillae
Decrease in “interdigitation”
epidermis held less tightly
Looser feel of ageing skin
By age 80yr keratinocyte turnover in epidermis slows to 50%
Age related changes – “normal” ageing
Dermis
Reduction in fibroblast numbers
Less matrix turnover
Dermis thins more than epidermis (transparency)
Collagenous fibres become larger and coarser
Fat, water, matrix content diminishes
Elastic fibres less resilient
Formation of cross links; some calcification
Skin less able to “smooth out”
Wrinkles
Loss of smooth padding provided by fat cells of the hypodermis
Age related changes – “normal” ageing
Dermis
Reduction in sweat glands and sebaceous glands
Gradual atrophy
Sweat less; drier and scaly skin
Reduced ability to regulate body temperature
Heat exhaustion more likely
Generalised reduction of blood flow to skin
Skin surface cooler; slow growth of hair and nails
Nails yellowish, ridged, thicker with Ca 2+ deposits
Decrease in hair follicles, loss of body hair
cf (males) eyebrow, nostril, ear hair becomes coarse and grow more rapidly Reduced hair pigment – grey/white is default colour
Age related changes – “normal” ageing
Hypodermis
Layer of loose connective tissue, containing fat
Subcutaneous tissue; not part of skin (technically)
…. but changes affect skin….
Generalised loss of fat; most obvious in face and limbs
Major cause of wrinkles
“old age is when, upon getting out of the bath, you notice the full length mirror is steamed up – and you are glad of it” (Modern Maturity)
Age related changes – “normal” ageing
Hypodermis
Loss of subcutaneous fat also loss of padding
Combine with reduction of blood supply to skin
Bed sores in areas of constant pressure over bony prominences
Loss of fat
Diminished insulation; allows heat to escape
Need to keep rooms warmer than young people can tolerate
“Age” or “liver spots”
Intrinsic – resulting from the ageing process
Resulting from UV damage: photo-ageing
dermatoheliosis
Free radical damage
Lipofuscin deposition in cells, often in secretary cells of sweat glands
End product of lipid peroxidation
Senile FRECKLES involving melanocytes
pigmented area (melanin) surrounded by normal-appearing skin.
melanocytes are present; may be increased in number
may evolve slowly over years, or may be eruptive and appear suddenly
Pigmentation may be homogeneous or variegated, with a colour ranging from brown to black. cf solar LENTIGO
Age related dysfunctions
Senile angiomas
75% >70yr
Elevated clusters of dilated capillaries Seborrheic keratosis
Benign epidermal tumours
Greasy wart-like crust often forms on surface of tumours Senile pruritis (itching)
Loss of oil secreting sebaceous gland
Dry, less pliant skin; cracks
Deep fissures that exude tissue fluid
Herpes Zoster (shingles)
Viral disease Peak incidence 50-70yrs Varicella (chicken pox) when young Remains dormant in nervous system When reactivated, attacks sensory nerve fibres and skin supplied by nerves Itching, red papules, fluid filled vesicles, dries down and forms crust, scales off, leaving pigmented area 1 – 2 weeks, pain for months
Skin Cancers
cancers of all types increase with age
Melanoma – most serious
Associated with sun UV light
Develops in pigment cells (melanocytes) of a pre existing epidermal mole
Non-melanoma skin cancers >50%
pink, red or white
Basal cell carcinoma
Most common
Develops from cells in basal layer of epidermis Most common in regions with strong sunlight
Most prevalent in light skinned races Head and neck usually Rarely metastasise Variously reddish patches; small open sores; bumps Growths can invade underlying tissue
Non-melanoma skin cancers
Squamous cell carcinoma
Less common
Associated with excessive sun exposure
More common in elderly, esp. older men
Appears as a wart
Often in form of hard nodule, with small reddened areas showing through surface
May be ulcerous