Pulmonary Circulation + LD Flashcards
What is the pressure and resistance in pulmonary circulation compared to systemic?
Low
What is the main structural difference between pulmonary and systemic arteries?
Pulmonary = less elastin + smooth muscle
Where do pulmonary arteries carry blood?
Carry deoxygenated blood from right ride of heart to lungs
Where do systemic arteries carry blood?
Carry oxygenated blood from left side of heart to all organs + tissues
What is the primary function of pulmonary circulation?
Gas exchange
What is the primary function of systemic circulation?
Provision of oxygen and metabolic substrates to organs + tissues + remove waste
What is the normal pulmonary BP?
25/10 mmHg
What is the normal systemic BP?
120/80 mmHg
Why is the left ventricle larger?
Thicker + more muscular than right as it needs to generate more pressure to perfuse systemic circulation
How is systemic circulation pressure managed?
Sphygmomanometer - non invasive
Hows is pulmonary circulation pressure managed?
Right heart catheterisation - invasive
What is the effect of gravity on lung perfusion?
Increased pressure in lower lung zones > opens + distends small BV/s > increasing blood flow
Describe regional ventilation in the lungs
Intrapleural pressure more -ve in upper regions so alveoli more expanded + reduced compliance
Ventilation > and more effective in lower regions
What is the normal V:Q ratio range?
0.8-1.2
Describe ventilation and perfusion at the apex
Ventilation > Perfusion
Increased V:Q
Describe ventilation and perfusion at the base
Perfusion > Ventilation
Reduced V:Q
What happens in localised LD?
Diverts blood away from poorly > well ventilated areas
Localised hypoxic vasoconstriction
What happens in severe/generalised LD?
Widespread hypoxic vasoconstriction > adverse effects
= Increased pressure + resistance > cor pulmonale
What are the acute effects of high altitude?
Hypoxic vasoconstriction
Increased pressure + resistance = extravascular fluid accumulation = high altitude pulmonary oedema
What happens to pulmonary vascular resistance as CO increases?
Decreases due to
- Recruitment - increased BF opens up closed vessels
- Distension - vessel walls thins + highly compliant
What can cause pulmonary hypertension?
- Disease of vessel
- Left heart damage - mitral valve regurgitation
- Lung disease/hypoxia - fibrosis
- Clots
How does pulmonary hypertension affect the right ventricle?
Increased right ventricle workload
- PV narrowing = increased RV load
- RV under strain so increases muscle contractility + wall thickens
- To maintain CO, RV dilates and HR increases
= impairment of venous return
What is cor pulmonale?
RV enlargement secondary to LD that causes PH
What are the clinical signs of right heart failure?
- Raised JVP
- Tricuspid regurgitation
- Peripheral oedema
- Ascites
