lecture 14 Flashcards
(29 cards)
What is ageing characterized by?
Accumulation of change, which may include dementia, atherosclerosis, and arterial fibrosis.
How do collagen changes affect ageing?
Collagen changes lead to aortic elasticity loss, which can cause hypertension and atheroma.
What factors influence ageing?
Genetic factors, diet, disease, environment, and cellular alterations.
Describe the general process of ageing.
Ageing is a normal, natural process that occurs at different rates and has a species-specific upper limit.
What is the approximate cell division limit in ageing?
Cells undergo approximately 50 divisions.
What is the “1.5 billion heartbeats” concept related to ageing?
It suggests that some species, including humans, have a lifespan roughly limited by the number of heartbeats, estimated at around 1.5 billion.
What factors may determine life span?
It may be natural, species-specific with an upper limit, size-dependent, and affected by BPM (beats per minute), with cardiac mitochondria releasing more free radicals.
What increases with ageing?
The risk of disease.
What are some deceptive external signs of ageing?
Greying of hair and wrinkling of skin.
What physical changes occur with ageing? (Name any three)
Decrease in height, narrower shoulders, and changes in ligaments and tendons.
How does ageing affect skin and nails?
It leads to dermal thinning, drier skin, decreased nail growth rate, and increased nail thickening.
What happens to the cardiovascular system with ageing?
There is a decrease in cardiac output (CO), vessel elasticity, and an increase in vessel wall weakening.
List some endocrine and metabolic changes that occur with ageing.
Less responsive pancreas, decreased sex hormones, decreased GIT secretions, and reduced absorption.
How does ageing affect the respiratory and muscular systems?
It leads to decreased lung elasticity, reduced lean body mass, and loss of muscle tone.
What does cellular ageing depend on?
Cell age and replicative capacity.
What are the approximate lifespans of various cell types?
- Epithelial cells: 2 weeks
- RBCs: 4 months
- Liver cells: 300 to 500 days
- Osteocytes: 15 years
- Neurons: have a massive range.
What are key factors in cellular ageing?
Decreased replication, senescence, telomeric shortening, and reduced telomerase.
What is Progeria?
An ageing disease characterized by shortened telomeres.
How did Progeria contribute to scientific understanding?
It helped identify telomere processes.
What are common complications in Progeria?
Early death often due to atherosclerosis.
What are the main theories of cellular ageing?
- Antagonistic pleiotropy
- Accumulation of damage
- Disposable soma theory
- Caloric restriction
What is antagonistic pleiotropy in cellular ageing?
It suggests that some genes have pleiotropic effects, benefiting the organism early in life but causing damage later. Example: P53 (tumour necrosis factor, pro-apoptotic).
How does the accumulation of damage theory explain ageing?
It proposes that free radicals and progressive mitochondrial damage contribute to cellular ageing. There is debate over whether free radicals are a cause or a correlation.
What is the disposable soma theory of ageing?
It suggests that organisms allocate limited resources to reproduction rather than long-term body maintenance, leading to ageing.
