Pulmonary Circulation + LD

Question 1

What is the pressure and resistance in pulmonary circulation compared to systemic?

Answer 1

Low

Question 2

What is the main structural difference between pulmonary and systemic arteries?

Answer 2

Pulmonary = less elastin + smooth muscle

Question 3

Where do pulmonary arteries carry blood?

Answer 3

Carry deoxygenated blood from right ride of heart to lungs

Question 4

Where do systemic arteries carry blood?

Answer 4

Carry oxygenated blood from left side of heart to all organs + tissues

Question 5

What is the primary function of pulmonary circulation?

Answer 5

Gas exchange

Question 6

What is the primary function of systemic circulation?

Answer 6

Provision of oxygen and metabolic substrates to organs + tissues + remove waste

Question 7

What is the normal pulmonary BP?

Answer 7

25/10 mmHg

Question 8

What is the normal systemic BP?

Answer 8

120/80 mmHg

Question 9

Why is the left ventricle larger?

Answer 9

Thicker + more muscular than right as it needs to generate more pressure to perfuse systemic circulation

Question 10

How is systemic circulation pressure managed?

Answer 10

Sphygmomanometer - non invasive

Question 11

Hows is pulmonary circulation pressure managed?

Answer 11

Right heart catheterisation - invasive

Question 12

What is the effect of gravity on lung perfusion?

Answer 12

Increased pressure in lower lung zones > opens + distends small BV/s > increasing blood flow

Question 13

Describe regional ventilation in the lungs

Answer 13

Intrapleural pressure more -ve in upper regions so alveoli more expanded + reduced compliance
Ventilation > and more effective in lower regions

Question 14

What is the normal V:Q ratio range?

Answer 14

0.8-1.2

Question 15

Describe ventilation and perfusion at the apex

Answer 15

Ventilation > Perfusion

Increased V:Q

Question 16

Describe ventilation and perfusion at the base

Answer 16

Perfusion > Ventilation

Reduced V:Q

Question 17

What happens in localised LD?

Answer 17

Diverts blood away from poorly > well ventilated areas

Localised hypoxic vasoconstriction

Question 18

What happens in severe/generalised LD?

Answer 18

Widespread hypoxic vasoconstriction > adverse effects

= Increased pressure + resistance > cor pulmonale

Question 19

What are the acute effects of high altitude?

Answer 19

Hypoxic vasoconstriction

Increased pressure + resistance = extravascular fluid accumulation = high altitude pulmonary oedema

Question 20

What happens to pulmonary vascular resistance as CO increases?

Answer 20

Decreases due to

1. Recruitment - increased BF opens up closed vessels
2. Distension - vessel walls thins + highly compliant

Question 21

What can cause pulmonary hypertension?

Answer 21

• Disease of vessel
• Left heart damage - mitral valve regurgitation
• Lung disease/hypoxia - fibrosis
• Clots

Question 22

How does pulmonary hypertension affect the right ventricle?

Answer 22

Increased right ventricle workload

1. PV narrowing = increased RV load
2. RV under strain so increases muscle contractility + wall thickens
3. To maintain CO, RV dilates and HR increases

= impairment of venous return

Question 23

What is cor pulmonale?

Answer 23

RV enlargement secondary to LD that causes PH

Question 24

What are the clinical signs of right heart failure?

Answer 24

• Raised JVP
• Tricuspid regurgitation
• Peripheral oedema
• Ascites