Thats heavy gravity can affect oxygen and carbon

That's heavy
Gravity can affect oxygen and carbon dioxide transport by influencing pulmonary circulation. Gravity pulls more
unoxygenated blood to the lower and middle lung lobes relative to the upper lobes, where most of the tidal
volume also flows.
No uniformity
As a result, neither ventilation nor perfusion is uniform throughout the lung. Areas of the lung where perfusion
and ventilation are similar have good ventilation-perfusion matching. In such areas, gas exchange is most
efficient. Areas of the lung that demonstrate ventilation-perfusion inequality result in less efficient gas exchange.
Diffusion
In diffusion, molecules of oxygen and carbon dioxide move between the alveoli and the capillaries. Partial
pressure (the pressure exerted by one gas in a mixture of gases) dictates the direction of movement, which is
always from an area of greater concentration to one of lesser concentration.
Let's move it!
During diffusion, oxygen moves across the alveolar and capillary membranes, then dissolves in the plasma, and
passes through the red blood cell (RBC) membrane. Carbon dioxide moves in the opposite direction. (See
Exchanging gases,
page 300. )
Spaces in between
Successful diffusion requires an intact alveolocapillary membrane. The alveolar epithelium and the capillary
endothelium are composed of a single layer of cells. Between these layers are minute interstitial spaces filled
with elastin and collagen.

P.300
P.301
Exchanging gases
Gas exchange occurs very rapidly in the millions of tiny, thin-membraned alveoli within the respiratory units.
Inside these air sacs, oxygen from inhaled air diffuses into the blood while carbon dioxide diffuses from the
blood into the air and is exhaled. Blood then circulates throughout the body, delivering oxygen and picking
up carbon dioxide. Lastly, the blood returns to the lungs to be oxygenated again.
From the RBCs to the alveoli
Normally, oxygen and carbon dioxide move easily through all of these layers. Oxygen moves from the alveoli into
the bloodstream, where it's taken up by Hgb in the RBCs. From there, it displaces carbon dioxide (the by-product
of metabolism), which diffuses from the RBCs into the blood, and then it moves to the alveoli. Most transported
oxygen binds with Hgb to form oxyhemoglobin while a small portion dissolves in the plasma (measurable as the
partial pressure of oxygen in arterial blood).
Up and down
After oxygen binds to Hgb, the RBCs travel to the tissues. At this point, the blood cells contain more oxygen, and
the tissue cells contain more carbon dioxide. Internal

P.302
respiration occurs during cellular diffusion, as RBCs release oxygen and absorb carbon dioxide. The RBCs then
transport carbon dioxide back to the lungs for removal during expiration.
Acid-base balance
The lungs help maintain acid-base balance in the body by maintaining external and internal respiration. Oxygen
collected in the lungs is transported to the tissues by the circulatory system, which exchanges it for the carbon