pathology of ageing Flashcards
What is the Hayflick limit?
a limit to how many times a human cell can divide
why would skin cels from older people divide less than younger people?
This is because at each cell division the telomere region at the end of chromo- somes shortens and eventually becomes so short that it is not possible for the chromosomes to divide and replicate so the cell can no longer divide. Telomere length appears to be paternally-inherited.
in some inherited conditions how is ageing greatly accelerated?
due to mutations in cell membrane proteins which make cell division impossible.
list the factors which may cause damage to non dividing cells?
- cross linking or mutations of DNA
- cross linking of proteins
- loss of calcium influx conrols
- accumulation of toxic by- products of metabolism
- telomere shortening
- time dependent activation of ageing and death genes
- free radical generation
- per oxidation of membranes
- loss of DNA repair mechanism
- Damage to mitochondrial DNA
name the only definitive method of slowing down ageing universally
calorie restriction- presumably reduces these metabolic products
how can ageing in specific parts of the body be reduced?
by specific local measures- e.g high sun protection factor cream to reduce UV cross linking of proteins in the dermis
how is wrinkling of skin caused?
(dermal elastosis) is caused by UV-B light causing cross-linking of the proteins, especially collagen, in the dermis.
how can ageing in the skin be reduced?
by avoiding too much sun exposure and using high sun protection factor cream.
how are cataracts in eyes caused?
cataracts are cause by UV-B cross-linking of proteins in the lens causing opacity.
describe osteoporosis in ageing
loss of bone matrix predominantly in women after the menopause.
describe alzheimers dementia in ageing- how can it be prevented
Alzheimer’s dementia doesn’t as yet have a fully un- derstood pathogenesis but there are genetic factors and lifestyles factors which can prevent it e.g. exercise, not being obese.
what are the effects of ageing in loss of muscle- sarcopaenia? causes?
may be the thing that prevents independent living in older people due to problems such as getting out of chairs and upstairs.
May well be caused by reduced levels of growth hormone and testosterone in later life.
how does deafness occur in ageing?
the hair cells in the cochlear do not divide so if they are damaged by high volumes they will die and not be replaced eventually producing deafness.
how can cataracts be prevented?
Can be prevented by wearing sunglasses that cut out UV light
how can cataracts be treated?
Can be treated by replacement of the lens with a plastic implant.
