Question

Name 13. During gas exchange in the lungs, several factors affect the rate of gas diffusion across alveolar (the alveoli are tiny air sacs in the lungs) and tissue membranes. One of the factors is the difference in partial pressures of the gases across the membranes. The gases will diffuse from an area of high partial pressure to an area of low partial pressure, Look at the illustration below and note which blood vessels carry blood away from the lungs (arterial blood) and which blood vessels carry blood to the lungs (venous blood). The numbers on the diagram are the partial pressures of O and COa (mm Hg) in each of the areas shown Pg03mm Hg P159 mm Hg Pulmonary Pulmonary Righe Let Venous Blood Aota Atterial blood peos40mm H Po1 100 mm Hg Pee 48 mm Hg Vena Pog 40mm Hig cavao Right vontricle Left ventricle oxygen-poor blood cxygen-rich blood Tissues Posg 60 mm Hg Poe- 30 mm Hg from the alveoli into Use the data in the diagram above to explain why oxygen diffuses the blood and from the blood into the tissues of the body Use the data in the diagram above to explain why carbon dioxide diffuses from the tissues into the blood and from the blood into the alveoli and then finally out into the atmosphere 14. In certain lung ailments such as emphysema, there is a decrease in the ability of oxygen to diffuse into the blood. How would the partial pressure of oxygen in the blood change? Why does a person with emphysema sometimes use a portable oxygen tank? Work Checlk 12-8

Answer 1

13.

a) partial pressure of O₂ (P_O2) is higher in atmosphere (P_O2 = 159 mm Hg) than in alveoli or arterial blood (100 mm Hg) so it diffuses from atmosphere to alveoli blood or arterial blood. Arterial blood has higher partial pressure of O2 than tissues (30 mm Hg) so oxygen diffuses from blood into the tissues.

b) It is for CO2 diffusion. It is just reverse of the O2 diffusion. PO2 in tissues is 60 mm Hg which is higher than Venous blood (46 mm Hg) so CO2 diffuses from tissues into the venous blood. In alveoli its partial pressure is 40 mm Hg so it diffuses to alveoli then from alveoli (40 mm Hg) to atmosphere (PCO2 = 0.3 mm Hg)

14. The partial pressure of oxygen in blood is decreased. So with the use of portable oxygen tank the partial pressure of atmosphere or intake air has been increased for more diffusion into the blood into the lungs.