Explanation: The blood–air barrier (alveolar–capillary barrier or membrane) exists in the gas exchanging region of the lungs. It exists to prevent air bubbles from forming in the blood, and from blood entering the alveoli. ... The barrier is permeable to molecular oxygen, carbon dioxide, carbon monoxide and many other gases.
containing several double or triple bonds between carbon atoms. Polyunsaturated fats, which are usually of plant origin, are regarded as healthier in the diet than saturated fats.
