Ageing heart and lungs

Question 1

Describe what happens to veins as they age

Answer 1

• Veins dilate and stretch with reduced elasticity
• Intima and muscle walls thicken
• Does not have very much affect on function

Question 2

What 3 things occur to cause thickening of the arterial wall?

Answer 2

• Increased collagen
• Reduced elastin
• Calcification

Question 3

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?

Answer 3

Increased systolic blood pressure

Question 4

Describe what happens to the arteries in terms of nitric oxide levels

Answer 4

• Reduced nitric oxide production by endothelial cells
• Bioavailability of nitric oxide reduces w/ ageing
• Nitric oxide lowers risk of atheroma formation (?)
• Vasoconstriction is promoted

Question 5

What happens to the cardiac myocytes (heart muscle)?

Answer 5

• 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

Question 6

What happens to ventricular filling with age?

Answer 6

• 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

Question 7

What happens to the heart rate with age?

Answer 7

• Intrinsic heart rate reduces by 5-6 beats/min per decade
• Max heart rate achieved reduces with age
• Variability of heart rate reduces

Question 8

What happens to the cardiac output with age?

Answer 8

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

Question 9

What changes occur within the conducting system of the heart?

Answer 9

• 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

Question 10

What are the 3 outcomes of the ageing conduction system?

Answer 10

• Premature atrial beats
• Ventricular ectopics (premature/irregular beat)
• Higher risk of clinically significant arrhythmias

Question 11

What happens to the heart valves during ageing?

Answer 11

• Thicken and stiffen
• Calcification
• Scarring
• Murmurs due to thickened valves

Question 12

What are the overall impacts of an ageing CVS?

Answer 12

• Increased systolic blood pressure
• Reduced heart rate (esp max HR)
• Reduced cardiac output reserve
• Increased risk of arrhythmias
• Increased risk of heart murmurs

Question 13

What happens to the alveoli with age?

Answer 13

• Reduced elastic tissue in alveoli ducts -> thinner
• Reduced SA for gas exchange
• Decreased elastic recoil -> small airways collapse

Question 14

Why is gas exchanged reduce in an older person?

Answer 14

• 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

Question 15

How does carbon dioxide excretion change with age?

Answer 15

It doesn’t - stays the same

Question 16

How does chemoreceptor function alter with age?

Answer 16

• Impaired chemoreceptor function
• Reduced ventilatory response to reduced PaO₂ or increased PaCO₂

Question 17

Why is there increased chest wall stiffness with age?

Answer 17

• Degenerative changes in intercostal, intervertebral + costovertebral joints
• Kyphoscoliosis
• Weaker respiratory muscles
• Increased work of breathing during stress

Question 18

What changes occur in the respiratory muscles?

Answer 18

• Weaker
• Diaphragm flattens + becomes less effective
• Intercostal muscles weaken
• Abdominal muscles play greater role

Question 19

What happens to pulmonary function, in terms of the following:

• Forced vital capacity
• FEV1
• Total lung capacity
• Residual volume
• LFTs

Answer 19

• 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

Question 20

Why do elderly people have a less effective cough?

Answer 20

• Reduced muscle strength
• Less sensitive cough reflex

Question 21

Why is mucociliary clearance less effective?

Answer 21

• Reduced number of cilia
• Slower + less effective
• Take longer to recover after insult

Question 22

How does surfactant composition change with age?

Answer 22

Increased proinflammatory proteins

Question 23

What are the overall impacts of an ageing respiratory system?

Answer 23

• Reduced gas exchange
• Reduced ventilatory response to reduce PaO₂ or increased PaCO₂
• Inceeased chest wall stiffness
• Reduced microbial defence mechanisms

Question 24

If there are all these problems with ageing lungs then how do 100 year olds run marathons?

Answer 24

• Ageing of the lung leads to mild functional deterioration
• It does not lead to symptoms without respiratory disease
• In those w/ resp disease, symptoms will progressively worsen w age even if disease remains stable
• When under stress (infection), earlier decompensation may occur