Ageing

Question 1

What is senescence?

Answer 1

The sum of all changes in an organism over time span of a normal life cycle leading to FUNCTIONAL IMPAIRMENT of cells, tissues and organs and finally death. NOT a disease.

Question 2

How does functional decline manifest?

Answer 2

Lung capacity decreases after 25-30Y
Amount of blood pumped by heart per unit volume. 
Speed of neurone electrical conductivity
Kidney filtration rate
Illness susceptibility.

Question 3

What must a valid theory of ageing account for?

Answer 3

Universal (all members of a given species)
Progressive
Deleterious.

Question 4

What evidence supports the programmed theory of ageing?

Answer 4

Max LS differs between species.
Longevity inheritance (primarily maternal side)
Genetic diseases of ageing.

Question 5

What is Hayflick’s limit?

Answer 5

The point at which mitotic cells lose mitotic capacity and can no longer divide. (50 doublings for human cells.)

Question 6

What is telomerase?

Answer 6

Has an RNA template ACCCAAC
And a reverse transcriptase domain
So synthesises DNA using own RNA template.
Allows regeneration of telomeres.
Immortalised cancer cells - 80% reactivate telomerase.

Question 7

Broadly speaking what evidence lis there for the telomere theory of ageing?

Answer 7

Telomere length directly proportional to age of cell
Telomeres lost faster from individuals with progeria.
Immortal cells have constant telomeres length.

Question 8

Why are senescent cells a problem?

Answer 8

Morphological changes (reduced strength)
Secrete pro-oncotic factors.
Secrete MMPs and inflammatory mediators
Lack of cell division (reduced tissue / wound repair).