Describe what happens to veins as they age
- Veins dilate and stretch with reduced elasticity
- Intima and muscle walls thicken
- Does not have very much affect on function
What 3 things occur to cause thickening of the arterial wall?
- Increased collagen
- Reduced elastin
With ageing, there is increased arterial wall stiffness and reduced compliance. Large arteries also can become elongated and tortuous. What does this in turn lead to?
Increased systolic blood pressure
Describe what happens to the arteries in terms of nitric oxide levels
Reduced nitric oxide production by endothelial cells
- Bioavailability of nitric oxide reduces w/ ageing
- Nitric oxide lowers risk of atheroma formation (?)
- Vasoconstriction is promoted
What happens to the cardiac myocytes (heart muscle)?
- Ventricular cardiac myocytes hypertrophy in response to increased afterload
- Enlargement of cardiac myocytes due to addition of sarcomeres
Apoptosis + necrosis of myocytes also occurs
- Problems with oxygenating these cells as they are thicker
What happens to ventricular filling with age?
- Left ventricular filling during early stage of diastole slows w/ age
- Adequate filling occurs in late stage of diastole by the left atria contracting
- Enlargement + hypertrophy of left atrium occurs
What happens to the heart rate with age?
- Intrinsic heart rate reduces by 5-6 beats/min per decade
- Max heart rate achieved reduces with age
- Variability of heart rate reduces
What happens to the cardiac output with age?
Reduced cardiac output reserve, due to:
- Reduced cardiac contractility
- Reduced blood volume in left ventricle
- Reduced maximum heart rate
During stress, cardiac output cannot increase
What changes occur within the conducting system of the heart?
- Reduced # of pacemaker cells at SAN
- Fibrous, fat + amyloid infiltration of conducting system
Slower propagation of electrical impulses due to hypertrophy
- Atrioventricular node less affected
What are the 3 outcomes of the ageing conduction system?
- Premature atrial beats
- Ventricular ectopics (premature/irregular beat)
- Higher risk of clinically significant arrhythmias
What happens to the heart valves during ageing?
- Thicken and stiffen
Murmurs due to thickened valves
What are the overall impacts of an ageing CVS?
- Increased systolic blood pressure
- Reduced heart rate (esp max HR)
- Reduced cardiac output reserve
- Increased risk of arrhythmias
- Increased risk of heart murmurs
What happens to the alveoli with age?
Reduced elastic tissue in alveoli ducts -> thinner
- Reduced SA for gas exchange
- Decreased elastic recoil -> small airways collapse
Why is gas exchanged reduce in an older person?
- They are perfusing parts of the lung that aren't getting properly ventilated so there is an increased ventilation-perfusion mismatch
- -> increased alveolar-arterial gradient
- Oxygenation not as efficient
- Reduced gas exchange
How does carbon dioxide excretion change with age?
It doesn't - stays the same
How does chemoreceptor function alter with age?
- Impaired chemoreceptor function
- Reduced ventilatory response to reduced PaO2 or increased PaCO2
Why is there increased chest wall stiffness with age?
- Degenerative changes in intercostal, intervertebral + costovertebral joints
- Weaker respiratory muscles
- Increased work of breathing during stress
What changes occur in the respiratory muscles?
- Diaphragm flattens + becomes less effective
- Intercostal muscles weaken
- Abdominal muscles play greater role
What happens to pulmonary function, in terms of the following:
- Forced vital capacity
- Total lung capacity
- Residual volume
- Forced vital capacity decreases
- FEV1 decreases
- Total lung capacity remainds the same
- Residual volume increases
- Ability to perform lung function tests properly decreases w/ age
Why do elderly people have a less effective cough?
- Reduced muscle strength
- Less sensitive cough reflex
Why is mucociliary clearance less effective?
- Reduced number of cilia
- Slower + less effective
- Take longer to recover after insult
How does surfactant composition change with age?
Increased proinflammatory proteins
What are the overall impacts of an ageing respiratory system?
- Reduced gas exchange
- Reduced ventilatory response to reduce PaO2 or increased PaCO2
- Inceeased chest wall stiffness
- Reduced microbial defence mechanisms
If there are all these problems with ageing lungs then how do 100 year olds run marathons?