Question

required information
which of the following is true at the arterial ends of the pulmonary capillaries?
multiple choice
the ( p _ { o _ { 2 } } ) is higher in the capillaries than in the alveoli.
the ( p _ { o _ { 2 } } ) is lower in the capillaries than in the alveoli.
the ( p _ { o _ { 2 } } ) is equal in the capillaries and in the alveoli.
the ( p _ { o _ { 2 } } ) is higher at first in the capillaries than in the alveoli, and then it is lower in the alveoli than in the capillaries.
the ( p _ { o _ { 2 } } ) is lower at first in the capillaries than in the alveoli, and then it is higher in the alveoli than in the capillaries.

Explanation:

Gas exchange in the lungs occurs based on partial pressure gradients. At the arterial ends of pulmonary capillaries, de - oxygenated blood (from the pulmonary artery) has a lower partial pressure of oxygen (\(P_{O_2}\)) compared to the alveoli (which have a high \(P_{O_2}\) due to inhalation). This gradient drives oxygen diffusion from alveoli to capillaries.

Answer:

The \(P_{O_2}\) is lower in the capillaries than in the alveoli.