Expansion
Pulmonary vessels carry blood for gas exchange; bronchial vessels nourish the lung tissue
Expansion
Pulmonary circulation - functional
- Pulmonary arteries carry deoxygenated blood from the right ventricle
- Low pressure, high flow
- Pulmonary veins return oxygenated blood to the left atrium
Bronchial circulation - nutritional
- Bronchial arteries arise from the descending thoracic aorta (and sometimes the upper posterior intercostals)
- Systemic pressure, low flow
- Supply the bronchi as far as the respiratory bronchioles, plus the visceral pleura
Bronchial venous blood partly drains into the pulmonary veins, delivering deoxygenated blood to the left atrium. This anatomical shunt is one reason arterial oxygen saturation never quite reaches 100 per cent in health.
The dual supply also explains why pulmonary embolism does not always cause infarction: the bronchial circulation can keep the tissue alive.