Question

What event is characteristic of the function in Zone 1 of the lung?

a. Blood flow through the pulmonary capillary bed increases in regular increments.
b. Alveolar pressure is greater than venous pressure but not greater than arterial pressure.
c. The capillary bed collapses, and normal blood flow ceases.
d. Blood flows through Zone 1, but it is impeded to a certain extent by alveolar pressure.

Answer 1

Zone 1 of the lung is characterized by alveolar pressure being greater than venous pressure but lower than arterial pressure, influencing the blood flow through the capillaries for gas exchange.

Step-by-step explanation:

The event characteristic of the function in Zone 1 of the lung is alveolar pressure being greater than venous pressure but not greater than arterial pressure. This condition occurs when alveolar pressure, due to ventilation, impedes some blood flow by pushing against the capillary walls, though arterial pressure is still able to push blood into the capillaries. This dynamic is influenced by the principles of pulmonary gas exchange, where oxygen and carbon dioxide are exchanged between the alveoli and the passing blood in the pulmonary capillary network. It's important to note that pulmonary arterioles can constrict or dilate to redirect blood flow to alveoli with sufficient ventilation, optimizing gas exchange.