Ageing process and theories of ageing Flashcards
What is ageing?
Progressive generalised impairment of function–> loss of adaptive response to disease.
What causes ageing?
Random molecular damage during cell replication
Stress, inactivity, poor diet and inflammation
What are the 7 proposed factors contribtuing to ageing?
- Mutations in chromosomes
- Mutations in mitochondria
- Intracellular aggregates (Caused my misfolding proteins)
- Extracellular aggregates eg amyloid and tower proteins in dementia
- Cellular loss
- Cellular senescense
- extracellular protein crosslinks eg diabetes glycosylation
What are telomeres?
The end part of each chromosome arm
Which base units form a telomere?
Multiple repeats of TTAGGG
What happens to a telomere after each replication?
It progressively shortens and eventually becomes too short to sustain replication
What is the Hayflick limit?
The number of times a normal human cell population will divide until cell division stops.
What is telomerase?
A ribonucleoprotein complex which can re extend shortened telomeres.
What causes damage damage to macromolecules?
Ionising radiation
Reactive oxygen species (From diet, radiation, inflammation)
Extrinsic toxins eg bisphenols
What are the 4 responses to cell damage?
Repair- Not possible when damage too great
Senescense
Apoptosis
Malignant transformation
What is the disposable soma hypothesis?
Repair requires energy and resource
i.e. repairing all damage not feasible
once body has reproduced no evolutionary value in repairing
Once reproductive age is over–> Damage not repaired
What is antagonistic pleiotropy?
Genes may be beneficial in early life and also deleterious in later life
They tend to be inherited as benefit early ie reproductive phase
Act as timebomb in later life causing cell senescence and death of organism
Define frailty
Loss of homeostasis and reislience–> Increased vulnerability to decompensation after a stressor event
How is the rockwood score calculated?
Take large number of body systems
Count how many have deficits
Divide by number of systems
Number between 0 and 1
How is the Fried score calculated?
1 point for:
- Unintentional wt loss
- Low grip strength
- Self reported exhaustion
- Low physical activity
- Slow walkign speed
0= Non frail 1-2= Pre-frail 3+ = Frail
