Physiology of ageing

Question 1

What is ageing?

Answer 1

The progressive generalised impairment of function resulting in a loss of adaptive response to disease

Question 2

What is human ageing?

Answer 2

Random molecular damage during cell replication that can be due to inactivity, poor diet, inflammation which all increase damage

Question 3

What are the proposed factors contributing to ageing?

Answer 3

Mutations in chromosomes - cancer development
Mutations in mitochondria resulting in cellular dysfunction
Intracellular aggregates
Cellular loss e.g. parkinsons
Cell senescence e.g. T2DM
Extracellular protein crosslinking - atherosclerosis and presbyopia

Question 4

What is the telomere?

Answer 4

End part of each chromosome arm which consists of multiple repeats of a single motif (TTAGGG) which form a DNA loop

Question 5

What happens to the telomere as the cell replicates?

Answer 5

It will shorten with each cell replication and eventually becomes too short to sustain cell replication leading to cell senescence

Question 6

What is the hayflick limit?

Answer 6

Limit to ageing - normal human cells can only replicate and divide forty to sixty times before it cannot divide anymore, and will break down by programmed cell death or apoptosis

Question 7

What is telomerase?

Answer 7

A ribonucleoprotein complex that can re-extend the shortened telomeres

Question 8

Describe damage to macromolecules in relation to ageing

Answer 8

DNA mutation
Lipid peroxidation
Protein misfolding, aggregation and crosslinking

Question 9

What causes damage to macromolecules?

Answer 9

Ionising radiation
Reactive oxygen species from diet, radiation and inflammation
Extrinsic toxins such as bisphenols

Question 10

What 4 cellular responses will damage result in?

Answer 10

Repair
Apoptosis
Senescence
Malignant transformation

Question 11

What is the disposable soma hypothesis?

Answer 11

Repair and maintenance of a body takes energy and resources and therefore once the body has reproduced or ended reproductive age, damage is not repaired at the same rate as it accumulates

Question 12

What is the antagonistic pleiotropy theory?

Answer 12

Genes that have a beneficial effect early in life in the reproductive phase will act as a timebomb later in life contributing to cell senescence and death of the organism

Question 13

What is an example of antagonistic pleiotropy?

Answer 13

Huntington’s gene - CAG repeats
Will lead to huntington’s disease later on in life but in early life will increase p53 gene and therefore those with the huntington’s gene are less likely to contract cancer

Question 14

What is frailty and what are the consequences?

Answer 14

Loss of homeostasis and resilience
Increased vulnerability to decompensation after a stressor event
Increased risk of falls, delirium, disability and death

Question 15

What are the 2 main models to measure frailty?

Answer 15

Rockwood

Phenotypic - fried score

Question 16

What is physical activity in old age protective of?

Answer 16

Heart disease
Diabetes
Some cancers
Mild depression 
Dementia and alzheimer's disease