Question

Which of the following is responsible for the movement of O2 from the alveoli into the blood in the pulmonary capillaries?

A) Filtration
B) Passive diffusion
C) Facilitated diffusion
D) Secondary active transport
E) Active transport

Answer 1

Passive diffusion is responsible for the movement of O2 from the alveoli into the blood in the pulmonary capillaries. It is the process by which molecules move from regions of higher concentration to regions of lower concentration.

Step-by-step explanation:

Passive Diffusion:

Passive diffusion is the movement of molecules over time by random motion (also called Brownian motion) from regions of higher concentration to regions of lower concentration. Significant passive diffusion across cellular membranes is limited to a few molecules, mostly gasses like O2, CO2, and N2, that can freely cross the hydrophobic phospholipid barrier. The rapid diffusion of gasses is essential for O2 and CO2 exchange between the alveolar capillaries and cells of the lungs during physiological respiration. O2 and CO2 exchange also occurs in mitochondria during cellular respiration. Diffusion across membranes does not require energy. In fact, diffusion releases energy recall the movement of protons through the F1 ATPase proton gate that synthesizes ATP during mitochondrial oxidative phosphorylation.