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Respiration, Part III

Oxygen and carbon dioxide are carried in the blood, pumped by the heart, and shifted through membranes by partial pressure gradients. Oxygen dissolves to a much smaller degree than carbon dioxide, so that at rest, the PO2 would only help provide 6% of the body’s O2 requirements. There must be another way. The hemoglobin molecule comes to the rescue.

heme groupHemoglobin is made of globin, a protein, and four heme groups consisting of an iron atom surrounded by an organic group. Four polypeptide chains make up the globin, each bearing a red-pigmented, disk-shaped heme. Each heme group binds one oxygen molecule, so each hemoglobin molecule binds four oxygens. Considering one red blood cell holds ~ 250 million Hb molecules, it can carry ~ 1 BILLION oxygen molecules (Marieb 581). The entire molecule… continue reading

Respiration, Part IV

Successful respiration requires a delicate acid-base equilibrium in bodily fluids. H+ concentrations, however meager they may be, significantly impact fluid pH. Furthermore, hydrogen ions are highly reactive and react with many compounds, often disrupting their shape and function.

Hydrogen ion concentrations must be maintained at ~4.0 x 10-8 in order to keep blood pH at its slightly alkaline value of 7.4. Acidosis, caused by accumulation of CO2 in the blood, is a drop in blood pH. Shallow breathing may cause acidosis. The opposite condition, alkalosis, is a rise in pH due to excessive CO2 excretion. Alkalosis is commonly caused by hyperventilation, but is much less serious than respiratory acidosis. We can say that concentrations of CO2 in the blood are directly related to its pH. A pH above 7.7 ([H3O+] = 2.0 x 10-8) or below 7.0 ([H3O+] = 1.0 x 10-7) is incompatible with life.

Somehow the body… continue reading

Conclusion, Links, Sources

In conclusion, I’ll talk about two things I’ve never even done: scuba (darn) and the bends (thank god). These underwater phenomena summarize very well the concepts I’ve outlined. As a note, this page would be set to some of my favorite music, but and don’t have sound samples for “Underwater Love” and “The Bends.” Shucks.

Back in the days when everything was still so simple, people devised novel ways of exploring the ocean floor. Take the little guy below, for example. The hood over his head connects him to surface air, and he can breathe fine, right? Wrong.

the bends - bungleWe would reason that a deep diver is subjected to increased “atmospheric” water pressure, a great force pressing in on his chest. Remember, water is heavier than air and exerts much more pressure? To give an idea, atmospheric… continue reading

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