Ageing

Question 1

What is the average world wide life expectancy?

Answer 1

• 67.2 years
  
  • Woman = 69.5
  • Men = 65.0

Question 2

Why do women on average live longer than men?

Answer 2

1. Delayed onset of cardiovascular disease in woman - possible due to hormones such as oestrogen.
   
   2. Woman have lower iron levels due to menstruation - not good to have too much iron, as its involved in the formation of damaging free radicals.
   3. Young men are involved in risky behaviour - more deaths
   4. 2 X chromosomes makes it less likely that some deleterious mutations on the X chromosomes are expressed

Question 3

Name 3 ocular examples of eye diseases that increases with age?

Answer 3

1. Cataract
   
   2. AMD
   3. Glaucoma

Question 4

What factors contribute to the decline function of various bodily systems with age?

Answer 4

• Cells stop dividing (mitosis) - as we age we start running out of cells
  
  • DNA constantly gets damaged - mechanism for repair decreases with age so we accumulate more harmful mutation with age
  • Protein synthesis - start making the wrong/ don’t make enough
  • Neuroendocrine - decreases with age, we start making the wrong quantities of hormone at the wrong time
  • Decline in immune function - White blood cells in immune system starts to break down with age
  • An increase in cellular free radical injury

Question 5

What are the 5 main changes associated with age?

Answer 5

1. Cellular/Morphological changes
   
   2. Connective tissue changes
   3. Reproductive system changes e.g. menopause
   4. Multisensory deterioration e.g. vision (presbyopia), hearing (presbycusis), taste, smell, pressure, temperature, proprioception and pain (loss of corneal sensitivity with age)

Immune system decline - an increased chance of infection in the elderly

Question 6

Explain the 5 cellular and morphological changes with age?

Answer 6

1. Cell loss - especially significant in amitotic tissue - since mitosis decrease by age therefore cells decrease. Cells that don’t replicate are affected such as cells in the CNS and cardiac muscles.
   Ocular Example: corneal endothelium - simple squamous epithelium which are hexagonal cells that tessellate - amitotic because as we age we loose these cells.
   Loss of skeletal and smooth muscle - wasting of iris dilator muscle may account for senile miosis
   
   2. Changes in cellular organelles e.g. mitochondria and endoplasmic reticulum. We start to make inappropriate proteins and not enough or cant generate the energy needed
   3. Accumulation of Lipofuscin e.g. RPE - A lot of cells are phagocytic where they inject other organisms and then the lysosomes break it down and produce junk, where most of the junk is removed via exocytosis and the remains are known as Lipofuscin. RPE, phagocytises outer segment disks and ingests them, as we accumulate more Lipofuscin in our RPE
   4. Accumulation of Advanced Glycation End products (AGEs) - this causes cross-linking between proteins. This is where the proteins start to bind to each other e.g. in blood vessels they will become less elastic as we age and more sclerotic due to accumulations of AGEs.
      Cross-linking between crystallines is associated with cataract as the lens fibres bind to each other and form this opacities
   5. Irreversible DNA Damage - as we age we damage out DNA but we have mechanisms for repairing that damage. Telomeres are there to protect the coding parts of the DNA and if they are damaged it can lead to cancer. As we get older these telomeres also shorten.

Question 7

Explain the connective changes with age?

Answer 7

1. Elastic tissue changes e.g. wrinkles and loss of arterial elasticity leading to increase blood pressure with age
   
   2. Enzymes that destroy collagen become more prominent e.g. ptosis
   3. Changes in cartilage - Osteoarthrosis
   4. Loss of bone structure such as stooping and mass- Osteopropsis
   5. Hair loss of mass and pigment

Question 8

What is the difference between proximate and ultimate?

Answer 8

The proximate cause is the immediate trigger e.g. what causes us to age - changes in our cells

The ultimate cause is the evolutionary explanation e.g. is there any adaptive significance to ageing/death

Question 9

What is the 2 ultimate cause of aging?

Answer 9

1. Tissues accumulate too much where the damage cannot be repaired to a point where we reach a limit what is biologically possible
   
   2. There is an evolutionary advantage to aging
      • The old make little contribution to rearing offspring and use up resources better allocated to the young
      • Antagonistic pleiotrophy - some genes that may be beneficial early in life but have deleterious effects in old age