Which of the Following is the CORRECT Order of Steps

Question

Which of the following is the CORRECT order of steps of gas transport and exchange?
A)ventilation, diffusion across the respiratory surface, circulation, diffusion between blood and cells
B)diffusion across the respiratory surface, ventilation, diffusion between blood and cells, circulation
C)ventilation, circulation, diffusion across the respiratory surface, diffusion between blood and cells
D)circulation, diffusion across the respiratory surface, ventilation, diffusion between blood and cells
E)diffusion between blood and cells, circulation, ventilation, diffusion across the respiratory surface

Accepted Answer

The correct order of gas transport and exchange starts with ventilation, where air is pulled into the lungs through inhalation and pushed out through exhalation. This is followed by diffusion across the respiratory surface, where oxygen (O2) crosses the respiratory membrane from the air into the blood vessels, and carbon dioxide (CO2) diffuses from the capillaries into the alveoli. Then, circulation takes place, where the O2-rich blood is carried from the lungs to the body tissues and organs, while at the same time the CO2-rich blood is transported from the body tissues and organs back to the lungs. Finally, diffusion between blood and cells occurs, where O2 diffuses from the blood into the cells, while CO2 diffuses from the cells into the blood for transport back to the lungs.