Fluid transport to and from the lungs is provided by which of the following? 1. Bronchial circulation 2. Lymphatic system 3. Pulmonary circulation

a. 2 and 3 only
b. 1 and 3 only
c. 2 only
d. 1, 2, and 3

ANS: D
The vascular supply of the lungs is composed of the pulmonary and bronchial circulations. The pulmonary circulation carries mixed venous blood from the systemic circuit to the lungs to in-crease O2 and reduce carbon dioxide content of blood. The bronchial circulation provides sys-temic arterial blood to the airways and pleura to support their metabolic needs. A network of lymphatics is also involved in fluid transport from the lungs. The lymphatic system removes fluid from the lung tissue and pleural space and returns it to the systemic circulation.