CO2 Transport in the Blood Flashcards
What are the 3 ways to transport CO2 in the blood? How much is transported with each method?
- Dissolved in plasma: 7%
- Bound to Hb: 23%
- Bicarbonate: 70%
What enzyme catalyzes the conversion of CO2 to bicarbonate?
Carbonic anhydrase
What happens to H+ and HCO3- levels during exercise?
H+ increases and HCO3- drops to restore equilibrium
What is the optimum blood pH for humans?
7.4
How does the amount of CO2 dissolved in the plasma compare for oxygenated and deoxygenated blood?
The same
How does the amount of CO2 bound to hemoglobin compare for oxygenated and deoxygenated blood?
More in deoxygenated blood
How does the carrying capacity of CO2 compare for oxygenated and deoxygenated blood?
Higher carrying capacity in deoxygenated blood
How is CO2 loaded on hemoglobin at the tissues?
Deoxygenation of hemoglobin at the tissues frees up binding spots, and CO2 is loaded as carbamino-hemoglobin
How is CO2 released from hemoglobin in the lungs?
Oxygen loading causes Hb to let go of the CO2
Where does the
CO2 + H2O H2CO3 H+ + HCO3- reaction occur?
Inside red blood cells
What is the membrane protein that sends bicarbonate across the cell membrane of red blood cells?
BandIII (an antiporter)
What is the mechanism of bicarbonate transport across the red blood cell membrane?
Chloride shift
What is the chloride shift?
BandIII brings one chloride ion into the red blood cell and send one bicarbonate out
What is a metabolon?
A group of enzymes inside a cell that work together to perform a function
What is happening with the chloride shift at the tissues?
CO2 diffuses into the blood, where carbonic anhydrase converts it to bicarbonate, and BandIII sends the bicarbonate into the plasma and brings in one chloride
What is happening with the chloride shift at the lungs?
BandIII sends one chloride out of the cell and brings in one bicarbonate, carbonic anhydrase converts it back to CO2, which diffuses into the alveoli and gets exhaled
What are the curves on a pH-bicarbonate plot called?
Isopleths
What does the pH-bicarbonate plot tell physiologists?
Allows them to visualize what will happen to pCO2, pH, and bicarbonate levels if one of them changes
What is hyperventilation?
The loss of too much CO2 by increased ventilation that is greater than what is needed to remove metabolism produced CO2
What happens to CO2, pH, bicarbonate levels, and proton levels during hyperventilation? Which way does the carbonic anhydrase reaction shift?
CO2 drops, pH increases, proton levels and bicarbonate levels drop. Reaction shifts to the left
What happens to CO2, pH, bicarbonate levels, and proton levels during hypoventilation? Which way does the carbonic anhydrase reaction shift?
CO2 increases, pH drops, proton and bicarbonate levels increase
What condition is caused by hyperventilation?
Respiratory alkalosis
What condition is caused by hypoventilation?
Respiratory acidosis
What is hypoventilation?
Too much CO2 is retained by alveolar ventilation that is insufficient to remove the CO2 produced by metabolism
What is respiratory acidosis?
When ventilation can’t remove all the CO2 produced by metabolism, so the blood pH decreases
What is respiratory alkalosis?
When there is more ventilation than what is needed to remove the CO2 produced by metabolism, causing the blood pH to increase
What are metabolic acidosis and metabolic alkalosis?
The pH change is caused by changes in metabolism rather than ventilation
What causes metabolic acidosis?
Lactic acid buildup and diarrhea
What causes metabolic alkalosis?
Loss of protons from vomiting
What do central chemoreceptors detect?
CO2 levels
What do peripheral chemoreceptors detect?
O2 levels
How does altitude affect blood pH and ventilation?
At risk of hyperventilation since the air has less oxygen, and the breathing rate increases to accommodate for that, so we are losing more CO2 than we have so blood pH increases until the kidneys produce more red blood cells to carry O2
