Ageing Flashcards
What are the 4 key words associated with ageing?
Normal
Universal
Inevitable
Irreversible
(Disease is the opposite of these)
What are the four ageing theories?
- Evolutionary
- Cellular
- Molecular
- System
What is the evolutionary theory of ageing?
Cells of the body are not designed to live forever and are DISPOSABLE. As long as DNA in germ cells is intact and as passed on.
What affect do antioxidants have on free radicals?
They can “mop them up” (get rid of them)
Antioxidants are in things such as fruit and veg.
What are free radicles?
“highly reactive molecules which cause damage to cellular components”
Arise during metabolism and can cause damage due to factors such as pollution, cigarette smoke and radiation.
They damage DNA, lipids proteins and mitochondria and accumulates with time.
Free radicals decrease an organisms ability to maintain steady state (homeostasis)
What is the cellular theory of ageing?
Ageing is associated with mitochondrial dysfunction. It leads to reduced ATP production and generation reactive oxygen species.
Oxidative stress and disease
An imbalance between production of radical oxidative stress and antioxidant results in oxidative stress. It causes intracellular damage and physiological decline. E.g. Cataracts, stroke, high BP, cancer, wrinkles.
What are telomeres?
They are a programmed part of the ageing process.
The body’s oxygen free radicals can modulate the reduction of telomeres.
When a cell stops replicating it enters a period of decline called CELL SENESCENE - this is the cellular equivalent to ageing (telomeres length reduces)
Homeostatic reserve mechanism
Ageing is a progressive physiological process that is characterised by degeneration of organs and systems and tissues with consequent loss of functional reserve in these systems.
Termed “homeostenosis” - It leads to increased vulnerability to disease that is seen with ageing.
What is homeostenosis?
A decreased ability to maintain homeostasis (balance) under stress. It is the impaired ability to compensate to physiologic challenges - things that used to be normal are no longer normal.
Damage that may be withstood in a younger person pushes the elderly beyond their functional capacity causing decompensation, disease or death.
What affect does a reduced functional reserve have on the respiratory system?
- Decreased blood flow to pulmonary circulation leads to decrease of diffusion in lungs
- Degeneration and reduced strength leads to an increase in righty of chest wall (less easy to expand rib cage)
- Muscle atrophy of pharynx and larynx which affects the cough reflex
- Decreased pulmonary elasticity = alteration in alveolar shape = ⬇️ SA for gas exchange
- Shorter/shallower breaths taken with decreased maximum breathing capacity
- Airway resistance is increased making it harder to draw air in to the lung and less ventilation at the lung base
How does changes in the respiratory system affect an older person who has developed a chest infection?
Narrowed airway due to inflammation and mucus production will further decrease air reaching lungs
Increase work of breathing will take more energy and could lead to breathlessness
Further decrease in gas exchange and decrease in O2 levels in blood (hypoxia)
Affects of ageing on nervous system…
Gradual loss of neurons and some supporting neuroglial cells (brain mass ⬇️ 10% between 20-90 yrs)
Loss of neurons in cerebral cortex = decrease in executive function (can take longer to understand instructions and remember info)
Loss of neurones in hippocampus = memory loss and decrease in acquisition skills
Cerebral flow decreases by around 20%
Spinal cord changes - sight, taste and smell loss
Reduced neurotransmitter production
How are synaptic connections maintained even with the loss of neurons?
Lengthening axons and sprouting dendrites allow synaptic connections to be maintained between neurones
What are the main issues that come with ageing?
Less able to recover from illness
Issues with maintenance of homeostasis
Functional capacity is decreased (esp when stressed)
