Ageing: Definition, Importance & Theories

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Questions and Answers

Which of the following accurately describes the definition of ageing?

An increase in the ability to survive

A decreasing ability to do work (correct)

A constant susceptibility to major diseases

An increase in lifespan for all species

What term refers to the maximum age that can be attained by a species?

Life expectancy

Senescence

Lifespan (correct)

Age-related disease

Which of the following is a type of antioxidant found within cells?

Superoxide dismutase (correct)

Catalase (correct)

Hydroxyl radical

Vitamin E

What effect does increased protein glycation have during ageing?

Altered activity of enzymes Signup and view all the answers

Which of the following correctly characterizes free radicals?

They are reactive due to unpaired electrons. Signup and view all the answers

What is lipofuscin commonly described as?

A waste material that accumulates in cells Signup and view all the answers

Which of the following is NOT a proposed cause of free radical damage?

Decreased blood sugar levels Signup and view all the answers

How do free radicals contribute to cellular damage?

By causing DNA/RNA modifications Signup and view all the answers

What is the Hayflick limit in terms of cellular biology?

A predetermined number of cell divisions Signup and view all the answers

Which of the following is NOT a characteristic of ageing in the immune system?

Increased antibody production Signup and view all the answers

Which of the following clinical presentations is associated with progeria?

Loss of subcutaneous fat Signup and view all the answers

What is the primary method known for slowing ageing in mammals?

Calorie restriction Signup and view all the answers

What effect does the decline in mitochondrial activity have on cellular functions during ageing?

Decreased cellular viability Signup and view all the answers

Which statement accurately describes the ageing process in the cardiovascular system?

Reduction in cardiac output Signup and view all the answers

Which of the following best describes the effect of the telomerase enzyme?

It can extend cellular division by rebuilding telomeres. Signup and view all the answers

What is a common cause of deaths in patients with progeria?

Coronary heart disease Signup and view all the answers

Which of the following occurs in the endocrine system during ageing?

Decline in hormone receptors Signup and view all the answers

How does calorie restriction contribute to anti-ageing effects?

Reduces age-associated mutations Signup and view all the answers

In what way is progeria characterized at the genetic level?

Sporadic dominant mutation Signup and view all the answers

Which aspect of eye ageing is NOT commonly mentioned?

Increased transparency of the lens Signup and view all the answers

Which company is known for researching genes responsible for longevity?

Centagenetix Signup and view all the answers

Study Notes

Ageing Definition and Importance

Ageing is defined as a decline in survival ability.
Ageing impacts work capacity, increases disease risk, and drives significant healthcare costs.

Ageing Terminology

Life expectancy: average age of death in a population.
Lifespan: maximum attainable age for a species.

Features of Ageing

Senescence: a natural decline in function
Age-related diseases: illnesses linked to ageing.
Senescent changes trigger and exacerbate age-related diseases.

Theories of Ageing

Wear and Tear Theory

Free radicals: highly reactive atoms/molecules causing cellular damage.
Glycation: reaction of sugars with proteins, leading to damage.
Waste products: accumulate in cells, hindering function.
Error-catastrophe: accumulation of errors in protein production harms cells.

Free Radicals in Ageing

Free radical damage increases with age.
Antioxidant defenses decrease with age.
Free radicals are atoms/molecules with unpaired electrons.
Free radicals damage DNA, RNA, proteins, enzymes, lipids, and cells.
Sources of free radicals include phagocytic cells, radiation, smoking, and oxidation-reduction reactions.
Types of Free Radicals: hydroxyl radical (OH), superoxide radical (O2), nitric oxide (NO).
Antioxidants delay or impede oxidation, protecting against free radical damage.
Extracellular antioxidants include vitamin E; intracellular antioxidants include superoxide dismutase (SOD) and catalase.
SOD protects cells from superoxide damage.

Protein Glycation in Ageing

Elderly populations are more susceptible due to glucose intolerance and diabetes.
Glycation increases cross-linking, alters enzyme activity, affects immunogenicity, and changes protein half-lives/receptor recognition.

Accumulation of Waste Products

Lipofuscin: lipid-rich pigment accumulating in cells, especially in long-lived tissues.
Lipofuscin is produced via free radical peroxidation of cell membranes.
The effects of lipofuscin accumulation are not fully understood.

Error-Catastrophe Theory

Abnormal proteins form due to transcription/translation errors.
Accumulation of abnormal proteins disrupts cellular function.
Genome-based factors like programmed ageing and mutations contribute.

Genome-Based Ageing

Programmed ageing: a genetically controlled process contributing to ageing.
Mutations: DNA replication errors that accumulate, affecting cell viability.
Hayflick Limit: cells divide a fixed number of times.
Telomeres shorten with cell division, limiting division potential.
Telomerase: enzyme that rebuilds telomeres.

Cellular Ageing

Reduced mitochondrial function impairs energy production.
Reduced DNA/RNA synthesis affects cellular processes.
Reduced nutrient uptake impacts cellular function.
Reduced chromosomal repair leads to DNA damage accumulation.
Accumulation of waste products (like lipofuscin) disrupts cellular homeostasis.
Changes in organelle shapes affect cellular integrity.

Ageing in Specific Systems

Immune System: declines in antibody production, T cell function, and thymus size. Increased autoimmune reactions.
Skin: wrinkles, pigmentation changes, hair loss, and impaired wound healing.
Lungs: decreased size, elasticity, and capacity reducing gaseous exchange.
Cardiovascular: stiffening of blood vessels, calcification, increased BP, and reduced cardiac output.
Kidneys: decreased volume, reduced nephron function, and impaired waste elimination.
Liver: reduced size and decreased function (e.g., drug detoxification).
Muscles: atrophy and reduced work capacity.
Endocrine System: decreased hormone production and receptor sensitivity.
Brain: loss of weight, nerve cells, and increased amyloid deposition.
Eyes: decreased lens flexibility, protein cross-linking.
Body Composition: reduced muscle, increased fat.

Progeria

Progeria (Hutchinson-Gilford syndrome): accelerated ageing.
Extremely rare (1 in 10 million).
Affected children age significantly faster.
Average lifespan ~13 years.
Common causes of death are heart disease and stroke.
Diagnosis is challenging due to rarity.
Management is focused on symptom relief and support.

Calorie Restriction and Ageing

Calorie restriction extends lifespan and delays age-related diseases in numerous species.
Calorie restriction may reduce age-associated mutations, free radical damage, and advanced glycation end products.

Anti-Ageing Therapy

Companies are pursuing research to slow/reverse ageing.
Companies researching anti-ageing therapies include Centagenetix, Elixir, Eurakon, Alteon, and Geron Corporation.
Ongoing studies and therapies target specific mechanisms of ageing.

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Description

This quiz explores the concept of ageing, its definition, and its significance in terms of health and healthcare costs. It also delves into key terminology related to ageing, features associated with it, and various theories such as the Wear and Tear Theory and the role of free radicals. Test your understanding of how ageing affects life expectancy and overall health.