Consider the following statements regarding human respiratory physiology: 1. The partial pressure of oxygen in alveolar air is higher than that in deoxygenated blood entering pulmonary capillaries, facilitating passive diffusion of oxygen into the blood. 2. Carbon dioxide is transported in the blood predominantly as dissolved gas in plasma. Which of the statements given above is/are correct?

💡 Solution & Explanation

Oxygen diffuses down its partial pressure gradient from alveoli into pulmonary capillary blood because alveolar oxygen tension is high. However, carbon dioxide is not transported mainly as dissolved gas; approximately 70 percent of carbon dioxide is carried as bicarbonate ions in blood plasma, with the remainder bound to hemoglobin or dissolved. Hemoglobin facilitates both oxygen and carbon dioxide transport. The respiratory rhythm center is located in the medulla oblongata of the brainstem.