The pathology of ageing

Question 1

How does a cell’s division capability change over time

Answer 1

Progressively undergoes fewer divisions

Question 2

What is a hay flick limit

Answer 2

This is the maximum number of cell divisions in a species

Question 3

What type of mammals tend to have high hay flick limits

Answer 3

Those with a larger lifespan

Question 4

What metric does the hay flick limit define

Answer 4

The shortening of the telomeres with each successive division

Question 5

Why are short-lived cells less effected by debris than longer-lived cells

Answer 5

They divide cytoplasmic debris with each of their daughter cells. This does not happen with long-lived cells

Question 6

Where does accumulated cytoplasmic debris originate from

Answer 6

1. Peroxidation of lipids forms indigestible lipofuscin
2. Intracellular aggregates of defective proteins
3. Defective mitochondria

Question 7

What is the inbuilt genetic mechanism of aging theory (clonal senescence)

Answer 7

1. Genetically we have an allowed lifespan that is finite

Question 8

Why do no wild animals live to the allowed lifespan of the genetic raging theory

Answer 8

Due to predation, infections and accidents

Question 9

Describe the replication senescence

Answer 9

1. Some cells stay with us from birth to death and we lose these cells during our daily life
2. Accumulation of lethal damage causes whole organism to succumb (e.g. CNS and cardiac)

Question 10

What is an accumulation of ‘lethal damage’

Answer 10

Cross-linking between proteins and DNA

Damage to mitochondria

Question 11

Where do free radicals form

Answer 11

1. Macrophages

2. Neutrophils

Question 12

How does defective repair result in raging

Answer 12

1. Hayflick phenomenon states cells can only divide a limited number of times under genetic control
2. If i damage the gastric mucosa, there may come a time where the cells can no longer replicate to heal the ulceration

Question 13

How does telomeric shortening cause ageing

Answer 13

1. Become too short that DNA polymerase in unable to find the start position for transcription
2. Associated with hay flick limit of cells

Question 14

What is sarcopenia

Answer 14

Part of the frailty syndrome

1. Reduced metabolic rate
2. Chronic poor nutrition
3. loss of muscle

Question 15

How does skin age

Answer 15

1. Loss of elastic recoil due to less collagen and elastin

Question 16

How does ageing effect bone

Answer 16

Loss of bone mass - osteoporosis as trabecular are thinned

Question 17

Why does osteoporosis occur

Answer 17

Accumulation of of minor traumas over time

Question 18

Why does immunity slow down with age?

Answer 18

1. Thymus is source of T cells and undergoes atrophy
2. Most of the thymus is replaced by adipose tissue
3. decreased output of native t cells

Question 19

What are cardiovascular changes that come with ageing

Answer 19

1. Distensability of arteries reduces with age + raised systolic blood pressure and PP
2. Ratio or collagen to elastin decreases in arteries as collagen levels increase
3. Calcification causes atheroma

Question 20

What happens to permanent cells during ageing

Answer 20

1. Decreased neurological function

2. Necrosis of tissues in the CNS

Question 21

Why are permanent cells in the heart and CNS a good thing

Answer 21

Very little chances of a tumour forming

Question 22

What are the clinical features of death

Answer 22

1. Pupils fixed in diameter
2. No corneal reflex
3. Vestibule-ocular reflexes are absent (no response to putting ice water in external ear canal)
4. No gag reflex
5. No respiratory movement
6. No motor response