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Physiology and theories of ageing
Ageing is a gradual decline in physiological reserve and in the capacity to restore balance after stress ("homeostenosis"); underlying it are accumulated damage (oxidative, DNA and mitochondrial), telomere shortening, cellular senescence and chronic low-grade inflammation — and clinically one must separate a normal change with age from disease.
Why it matters in the exam
The exam asks which changes are normal in old age and which require investigation: decline in glomerular filtration, rise in systolic pressure, fall in maximal heart rate, reduced thirst, lighter and earlier sleep, high-frequency hearing loss and presbyopia — as opposed to anaemia, confusion or functional loss, which are not "just age".
Other questions deal with theories of ageing (telomere shortening and the Hayflick limit, free radicals, cellular senescence with inflammatory secretion, "inflammaging", caloric restriction that prolongs life in animal models) and with demography: in Israel people aged 65 and over are about 12% of the population, a relatively low share for a developed country because of the high birth rate, and the fastest-growing group is those aged 85 and over.
Further changes that are asked about: in the lungs — a fall in FEV1 and chest wall compliance and a rise in residual volume; in the immune system — a weaker response to vaccines and less fever during infection, so infection may present as confusion or a fall without fever; and in the skin — thinning, dryness and slower healing. An "atypical" presentation of illness in an older adult is the rule, not the exception.
Key points
- Ageing = reduced reserve and reduced "return to balance".
- Mechanisms: accumulated damage, telomeres, cellular senescence, chronic low-grade inflammation.
- Normal: lower filtration, higher systolic pressure, reduced thirst, presbycusis.
- Not normal: anaemia, acute confusion, functional loss.
- In Israel: about 12% aged 65 and over; the fastest-growing group — 85 and over.
Summary table
| System | Normal change with age | What is not normal |
|---|---|---|
| Kidneys | Fall in filtration rate; creatinine may stay "normal" because muscle mass falls | A sharp rise in creatinine |
| Heart and vessels | Rise in systolic pressure, stiffer walls, lower maximal heart rate (about 220 minus age) | Heart failure, syncope |
| Fluids | Reduced thirst and urine-concentrating capacity | Dehydration and hypernatraemia |
| Brain and sleep | Slight slowing of processing speed; lighter and earlier sleep | Functional decline, acute confusion |
| Senses | Presbyopia, high-frequency hearing loss (presbycusis) | Sudden vision loss |
| Body composition | Less muscle and water, more fat | Unintentional weight loss |
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Sources
- Hallmarks of aging: an expanding universe (López-Otín et al.), 2023 — Primary, antagonistic and integrative hallmarks
- Hazzard's Geriatric Medicine and Gerontology, 8th edition (2022) — Biology of aging and physiological changes with age
- Israel Central Bureau of Statistics — the older population in Israel (65+), 2020–2024 — Demographic data
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.