9. Knowing what you know about how a substance travels in

diffusion, in order for oxygen to leave the alveoli and enter the

blood, there would be a [ HIGHER or LOWER ] concentration of

oxygen in the alveoli compared to the blood.

10. Knowing what you know about how a substance travels in

diffusion, in order for carbon dioxide to leave the blood and enter the

alveoli, there would be a [ HIGHER or LOWER ] concentration of

carbon dioxide in the alveoli compared to the blood.

11. Explain your reasoning for questions #9 and #10.

The movement of Oxygen from alveoli to the blood capillaries is possible due to simple diffusion through the paper-thin membrane between them due to the concentration gradient. The Concentration of oxygen in the alveoli is higher than the blood capillaries so the movement of oxygen takes place.

The CO2 concentration in the blood is higher than in the alveoli, so it diffuses through the membrane from high concentration to low concentration to the alveoli.

eyitbay eyitbay · Answer 2 · 2021-12-10T23:24:34+01:00

Higher pressure gradient in the alveoli to lower in the blood for oxygen transport.

Higher pressure gradient in the blood to the lower in the alveoli for C02 transport out of the cells.

Basically, the partially pressure of oxygen in the alveoli of lungs during external respiration is 104mmHg.Whereas in the blood this is 40mmHg. This pressure gradients forces 02 through the 1 cell layer thick into the blood.

The reverse is the case in the blood for C02 with higher partial pressure of45mmHg in the blood capillary compared to 40mmHg in the air. This forces air out of the blood into the alveoli to the air in the lungs.

During internal respiration, the partials pressure of 02 in the tissues is low 40mmHg,becaue of cellular respiration, but higher in the blood. Setting up partial gradient differences .Therefore 02 dissociates from the blood hemoglobin to the tissues.

The reverse is the case for C02 which is of higher pressure gradient in the tissues than the blood. The set up a gradients that diffuses C02 from the tissues to the blood (opposite direction), carried by HB of the blood to the alveoli for onward diffusion into the air in the lungs.

The alveoli( air sac) is located in the lungs and served at the medium of gas exchange between the air in the lungs and the blood.

The cells of its wall are 1 cell layer thick made up of squamous epithelium; this reduces the diffusion distance and therefore aids diffusion.

The walls are usually moist so that the gases can readily dissolved in the moist lining for diffusion thus ensures 02 is at the same temperature with the body temperature.

The thin surface ensure high surface area to volume ratio, which increases the rate of diffusion.

They close to the pulmonary capillaries to reduce diffusion distance.

These (partial pressure) gradients ensures continuous availabity of the 02 in the blood tissues and the removal of C02 from the blood.

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