Lecture 21 - Ageing Flashcards
As of 19 March 2020, who are the oldest living britons and when were they born
Robert Weighton and Joan Hocquard, both born on 29 March 1908.
( just under 102 years old )
Who is the oldest known living man in the world
Robert Weighton
What did Bob Weighton do
- Joined City, University of London as part of the Engineering department in 1947, where he worked as a Senior Lecturer in Mechanical Engineering until 1973.
- He recalled lecturing the students as being his fondest memory of the University
Which gender tends to live longer and by how man years
Women tend to outlive men by about 5 years
Who is the worlds oldest living person alive at the moment AND when was she born
Kane Tanaka
Born 2nd January, 1903
Facts about Kane Tanaka - oldest living person
- Japanese
- She is still in good health and occupies her time by playing board games, and doing calligraphy and calculations.
- She credits family, sleep and hope as her secrets for longevity.
- She likes sweets and drinks three cans of canned coffee and various sodas every day
Who is the oldest (authenticated) person ever and when she was born/died
Jeanne Calment
Born - 21/02/1875
Died - 04/08/1997
Facts about Jeanne Calment
- Met Vincent van Gogh - at 13 years in her uncles fabric shop where he wanted to buy canvas and described him as a mean guy
- Saw Eeifel tower being built in late 1880s
Has there always been old people and if so how do we know
YES - OLD AGE IS NOT A NEW PHENOMENON
Genesis 16:16 And Abram was fourscore and six years old (i.e.86), when Hagar bare Ishmael to Abram.
Exodus 7:7 And Moses was fourscore years old (80), and Aaron fourscore and three years old (83), when they spake unto Pharaoh.
What does fourscore years old mean
Bible talks about people being fourscore years old
Score = 20 so they would be 80 ( 4 x score (20) )
e.g. if “ fourscore and six years old” = 86
FOURSCORE = 80
In the past when did most people die
- At younger age:
- Although a few individuals in Palaeolithic times ( more than 2 million years old )may have survived beyond 60, due to disease, high infant mortality rate, predators and accidents, the majority of people will have died long before this, possibly most not living much beyond 30-40
- Victorian ( London, 115 years ago ) middle class men might live, on average, to 45. The average lives of workmen and labourers spanned just half that time. Children were lucky to survive their fifth birthdays.
What has happened to average life expectancy over the last hundred years and why
Increased ( with 2 obvious periods of decline)
Due to advances in sanitation and medicine
What % of girls born in 1951 and predicted to live up to over 100
13.5%
What % of girls born in 2060 are expected to reach 100
58.8%
What is the evidence to limited human lifespan ( how old humans can get )
“Driven by technological progress, human life expectancy has increased
greatly since the nineteenth century. Demographic evidence has revealed
an ongoing reduction in old-age mortality and a rise of the maximum age at death, which may gradually
extend human longevity…… Here, by analysing global demographic data, we show that improvements in survival with age tend to decline after age 100, and that the age at death of the world’s oldest person has not increased since the 1990s. Our results strongly suggest that the maximum lifespan of humans is fixed and subject to natural constraints.”
What is the average life expectancy worldwide
- 2 years
69. 5 for women, 65.0 for men
Why do women (on average) live longer than men?
- Delayed onset ( protected against) of cardiovascular disease in women (possibly due to high oestrogen levels).
- Women have lower iron levels than men (due to menstruation) – iron is involved in the formation of damaging free radicals so women have less damaging free radicals. Free radicals play havoc with cells
- Young men engage in risky behaviour e.g. fast driving, drinking, fights. On average, young men die younger due to TESTOSTERONE RUSH
- 2 X chromosomes makes it less likely that some deleterious mutations on the X chromosome are expressed ( males have 1 X chromosome ). If X chromosome carries recessive gene for disease, other allele on X chromosome in female would compensate for this. However, males only have 1 chromosome.
What is biggest killer in western world
Cardiovascular disease - affects more men than women
Which country has highest life expectancy
Japan - 82.6
What is life expectancy of UK
79.01
doesnt appear in top 10
Which country has lowest life expectancy and why
Swaziland - 39.6 ( 40% below world average )
Lowest = africa
Due to disease - aids, war, high infant mortality rate = decreases life expectancy
What is happening to age of population in Britain
Getting older
- The mortality rate for those over 75 years old in the UK has fallen sharply from 137 deaths per thousand per year in 1911-1915 to 83 deaths per thousand in 2006-2007.
- The number of people aged 80 or over has increased from 1.6 million in 1981 to 2.8 million in 2007
- Over the last 25 years the percentage of the population aged 65 and over increased from 15 per cent in 1983 to 16 per cent in 2008, By 2033, it is estimated that 23 per cent of the population will be aged 65 and over.
= ELDERLY IS FASTEST GROWING AGE GROUP IN THE UK
When do most diseases become more prevalent
As you age
Over 70 = number of sick people increase in upcoming years as population ages
What are the top 10 killers in western world
- Heart disease
- Cancer
- Stroke
- Chronic lower respiratory disease
- Accidents ( dont become more prevalent as you age )
- Diabetes
- Alzheimers disease
- Influenza and pneumonia
- Kidney disease
- Septicemia
What is Cataract, Age-Related Macular Degeneration and glaucoma more common in
Older population
Vision changes with age
What is disadvantage of people living longer
More old people = more sick people around world = more strain on healthcare system
What is the circle of life
- Egg ( fertilisation - 2 gametes fuse to form zygote )
- Embryo ( fetus )
- Baby
- Child
- Teen
- Adult
- Ageing
- Death
What happens to our bodies , including our eyes and visual system
Change enormously from the moment of conception, through periods of development and maturation to eventual senescence.
Go through life cycle - change from 1 lifestage to the next - different at different ages
Is old age a disease?
NO
Old age is normal just like how situation in adults is normal
What happens in body as you age
Multiple changes occur in our cells, connective tissue and organ systems - ‘ normal - changes
What are examples of normal changes as you age
- Cell loss
- Changes in organelles
- The accumulation of lipofuscin
- The accumulation of AGEs
- Irreversible DNA damage
- Changes in elastic connective tissue
- Changes in bone and cartilage
- Hair loss
- Reproductive changes
- Decreased immune function
- Multisensory deterioration
Cell loss as you get older
- Especially significant in amitotic tissue ( tissues where dead cells are replaced e.g. CNS neurons, cardiac muscle - lead to problems of myocardial infarction and stroke )
- Happens in some tissues, but not in others as we age
Ocular example of cell lose as you age
The cornea
Structure of cornea
- Cornea is This is a 5 layered structure with a protective stratified epithelium externally and a single layered endothelium internally
- Bulk of cornea made of alternating lamellae of collagen = corneal stroma
- 1 layer thick - faciliated diffusion of substances between aqueous humour and corneal stroma
- Endothelium separates aqueous humour from avascular cornea
How does cell loss occur in the cornea as you age
- The epithelium changes little with age as it is continually renewed by limbal stem cells - cells still die e.g. superficial cells BUT are replaced with basal cells from below - continuously replaced by stem cells at corneal limbus
- The amitotic cells of the endothelium increase in size and lose their regular (hexagonal) outline as neighbouring cells die. Corneal endothelium is amitotic = cells as they die are NOT replaced and holes created are filled by their migration of cells that still exist
- With age there is a decrease in cell density and an increase in the variability of cell size (polymegathism) and shape (pleomorphism)
SO ALTHOUGH CORNEAL EPITHELIUM CELLS DIE, STRUCTURE ITSELF DOESNT CHANGE BECAUSE CELLS ARE RENEWED
Difference in young and old corneal endothelium
Young: Cells regular in size and shape, all hexagonal and dense
Old: As you age (80), lost half of corneal endothelium cells - cells different sizes and shapes as existing cells migrated to fills holes left by dead cells
Loss of muscle as you age
- The decrease in pupil diameter with age (senile miosis) may be due to a loss of smooth muscle
- With age loss of skeletal muscle, skeletal muscle is replaced by fat (sarcopenia). Skeletal muscle declines after age of 25
Ocular example of muscle loss as you age
IRIS = 2 SMOOTH MUSCLES
- The circular iris sphincter muscle ( running around pupil ) causes pupil constriction (miosis) and the radial dilator ( which runs from iris roots to iris tips stopping where iris sphincter starts ) results in dilation.
- When radial muscle contracts, it dilates pupil
- Senile miosis may be due to a degeneration of the dilator muscle
- Age related constriction of pupil is due to washing og iris dilator muscle
What does retina contain and what are there light levels
- Retina contains 2 types of photoreceptors - rods and cones
- Rods = low light levels
- Cones = high light levels
What happens to retinal rods as you age and consequence of this
- Loss of retinal rods
- Lose rods with age so density of rods decreases as you age = need bright lights to read
- Children = more rods
How do organelles change as you age
For example protein synthesis is disrupted and energy production impaired by changes to ER ( disorganised ) and mitochondria = decreases efficiency of energy production
Accumulation of lipofuscin as you age
- This breakdown product of lysosomal action occurs in most cells e.g. liver,kidney
- It can be seen in
cardiac muscle and neural soma. - During phagocytosis
Where does lipofuscin accumulate in the eye
In the RPE, as a result of phagocytosis
What is RPE
- Retinal Pigment Epithelium
- Is in contact with the photoreceptors
- Main function: engulf other bits of photoreceptors and chew them off = photoreceptor renewal/ outer segment phagocytosis and these ingested bits of photoreceptors are destroyed by lysosomes but lipofusin accumulates in RPE
What is AGEs
Accumulation of Advanced Glycation End products
What causes AGEs
Cross linking between proteins
What is cross linking between proteins implicated in
- Alzheimer’s and diabetes
- Also partly responsible for age-related sclerosis of blood vessels. When cross linking of proteins happens in blood vessels, they become less elastic = hypertension
Ocular example of AGEs/ cross linking
Cross-linking between crystallins in the lens is involved in cataract formation
What is glycation
Bonding of sugar molecule to a protein
What is AGEs important in
Diseases e.g.Alzheimer’s and diabetes
Irreversible DNA damage as you age
- DNA is continually damaged ( especially when cell divides ) and is repaired by a host of mechanisms, the efficiency of which declines with age = damage DNA accumulates as you get older
- Telomere length declines in dividing cells as you age
- Each time a cell divides the ends of the chromosome are lost. Lose bit of telomere each time cell divides but coding DNA is protected = telomere shortens each time cell divides
- If no telomere or it becomes too short = lose bits of DNA useful each time cell divides eventually cells can no longer divide and becomes inactive and dies
What is telomere
A repetitive non - coding nucleotide sequence at each end of a chromosome.
Function of telomeres
- Protect the coding parts of the DNA
- Protect the chromosome especially when it divides during mitosis = prevents chromosome ends from fraying or sticking to each other
In red blood cells what is length of telomeres
8000 bps at birth to 3000 as people age and 1500 in elderly people
When else does shortening of telomeres happen
Cancer
What happens to elastic tissue as you age
Changes
Connective tissue/elastic fibres changes - loss of elasticity = wrinkles
-Less elasticity in blood vessels = increased hypertension with age.
What is wrinkles caused by
Loss of elasticity from change in elastic fibres as you age
Increase by exposure to sunlight
What does increased sclerosis of arteries result in
Increased hypertension with age.
BP = CO X PR
Peripheral resistance = measure of elasticity blood vessels
CO = Cardiac Output
Enzymes that destroy collagen upregulated as you age
e.g. Ptosis
What is ptosis
Drooping of eyelids in elderly people
What happens to blood vessels as you age
Less elastic - partly due to loss of elastic connective tissue and cross linking of proteins, due to AGEs
What else happens as you age
- Changes in cartilage (osteoarthrosis)
- Loss of bone (osteoporosis) = causes collapse of vertebrate = older people stooped and shorter than younger
- Hair (loss of mass and pigment) = esp if male
- Changes in the reproductive system - menopause ( males are fertile but female ovulate around 40/50 years old )
Multisensory deterioration as you age
Semi-circular canals ( problems with balance ), hearing (presbycusis), taste, smell, pressure, temperature, proprioception & pain
Others senses also affected by age
Number of chemosensory cells decrease as you age ( less sensory taste buds ) - half lost by age 50
Visual changes with age examples
Decreased corneal sensitivity
Decreased tear production and changes in chemical compostion of tears
Senile miosis - pupil decrease as older
Decreased accommodation - presbyopia
Decreased lens transparency
Decreased production & drainage of aqueous
Liquefaction of vitreous - increase rate of retinal detachment and floaters in elderly
Decreased sensitivity
Decreased acuity
Decreased temporal resolution
Changes in colour vision
What happens to immune system as you age
Declines - not as robust
SEE LECTURE SLIDES FOR SPECIFIC EXAMPLES
