Gas Exchange Flashcards
What is gas exchange?
Gas exchange is the biological process of swapping oxygen and carbon dioxide between the environment and the bloodstream, and ultimately between the blood and body tissues.
Where does gas exchange occur in the respiratory system?
In the alveoli of the lungs, where oxygen diffuses into the blood and carbon dioxide diffuses out into the alveolar air.
What is the alveolar–capillary membrane?
It’s the thin barrier between the alveolar air and the blood in the pulmonary capillaries, composed of alveolar and capillary walls, which allows efficient diffusion of gases.
What drives the movement of oxygen and carbon dioxide across the alveolar membrane?
Diffusion driven by differences in partial pressures (concentration gradients) of oxygen and carbon dioxide between the alveolar air and the blood.
What is meant by “partial pressure” in the context of gas exchange?
Partial pressure is the pressure exerted by an individual gas in a mixture of gases; it determines the direction and rate at which gases diffuse.
How do the structure and function of alveoli facilitate gas exchange?
Alveoli have thin walls, a large surface area, and are surrounded by dense capillary networks, all of which maximize the efficiency of oxygen and carbon dioxide diffusion.
What role does hemoglobin play in gas exchange?
Hemoglobin in red blood cells binds oxygen in the lungs and transports it to tissues; it also helps carry carbon dioxide back to the lungs for exhalation.
Where does gas exchange occur at the cellular level?
At the tissue level (internal or cellular respiration), where oxygen diffuses from the blood into the cells and carbon dioxide diffuses out as a waste product.
How do the partial pressures of oxygen and carbon dioxide differ between the alveoli and the blood?
In the alveoli, the partial pressure of oxygen is high and that of carbon dioxide is low; in the blood returning from tissues, oxygen is lower and carbon dioxide is higher, facilitating their diffusion in opposite directions.
