pathology of ageing Flashcards
how does ageing occur
dividing cells
telomeres get shorter after each cell division so chromosome cant divide and replicate – limiting the amount of division that can occur
this is why skin cells from older people will divide less than younger people
what is hayflick limit
limit to how many times a human cell can divide
what is progeria
inherited condition that accelerates ageing
due to mutations in cel membrane proteins that make dividing impossible
what happens to non dividing cells
they die once they have accumulated a certain amount of damage to their cellular systems
factors which cause damage to non dividng cells
- cross linking or dna mutations
- cross linikng of proteins
- loss of calcium influx controls
-damage to mitochondrial DNA - loss of DNA repair mechanism
- peroxidation of membranes
- free radical membranes
- telomere shortening
- accumulation of toxic byproducts of metabolism
.
what can prolong life
anything that reduces damage to cells
main way - calorie restriction to reduce toxic metabolic by products
or local measures eg sun cream to reduce UV
what is Dermal elastosis (impact of ageing on skin)
Accumulation of abnormal elastic in the dermis of the skin
Result of prolonged/ excessive sun exposure – photoaging
UV light causes protein cross-linking
what is osteoporosis (impact of ageing)
Caused by loss of coupling in the bone remodelling process – due to increased bone resorption or deceased bone formation due to a lack of oestrogen (hence why so many women are affected after menopause)
Can cause osteopenia
Bone matrix is mineralised as normal but the trabeculae are thinned – results in fractures from minor trauma
Liberates calcium – leading to hypercalciuria – risk of renal stone formation
how to prevent osteoprosis
hormone replacement therapy at menopause and calcium/vitamin d supplements
impact of ageing on eyes
cataracts form
caused by UV-B cross linking of proteins in the lens causing opacity
how to prevent catracts
sunglassses tht cut out uv light
how to treat cataracts
replacement of the lens with a plasic implant
what is sarcopaneia
impact of ageing
Decreased growth hormone, decreased testosterone, increased catabolic cytokines
can be prevented by regular excercise
what causes deafness
hair cells in cochlear cannot divide/regenerate – hence once damaged cannot recover
what causes senle dementia
Plaques and neurofibrillary tangles occur in brain
