Question

Describe the blood flow to both the conductive and exchange zones of the respiratory system. Which arteries feed them? What is the venous drainage?

Answer 1

Respiratory system has dual circulation.

1) Pulmonary circulation : It contributes to larger blood supply of the respiratory system. This circulation is required to oxygenate the deoxygenated blood pumped from the heart.

Pulmonary arteries carry deoxygenated blood from the heart to the lungs and its branches carries it to through the conducting zone of the lung. Gaseous exchange does not occur through the conducting zone.

At exchange zone, pulmonary arteries branches to form pulmonary capillaries which along with the endothelium of the exchange zone forms the respiratory membrane through which gaseous exchange occurs.

Then oxygenated blood is carried back to the heart via pulmonary veins.

2) Bronchial circulation : It carries oxygenated blood to supply the lung tissue via bronchial arteries and drains the deoxygenated blood by bronchial veins.