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Questions and Answers
What proportion of carbon dioxide is transported in the blood as bicarbonate (HCO3-)?
What proportion of carbon dioxide is transported in the blood as bicarbonate (HCO3-)?
- 90%
- 60% (correct)
- 10%
- 30%
Approximately what percentage of carbon dioxide is transported in the blood in the form of carbaminohemoglobin?
Approximately what percentage of carbon dioxide is transported in the blood in the form of carbaminohemoglobin?
- 60%
- 30% (correct)
- 90%
- 10%
In what form is the smallest proportion of carbon dioxide transported in the blood?
In what form is the smallest proportion of carbon dioxide transported in the blood?
- Dissolved CO2 (correct)
- Carbaminohemoglobin
- Bicarbonate (HCO3-)
- Carbonic acid
Why is the reaction of carbon dioxide dissolving in plasma to form hydrogen and hydrogen carbonate ions slow?
Why is the reaction of carbon dioxide dissolving in plasma to form hydrogen and hydrogen carbonate ions slow?
What is the relationship between the amount of CO2 that dissolves in plasma and the partial pressure of CO2 (pCO2)?
What is the relationship between the amount of CO2 that dissolves in plasma and the partial pressure of CO2 (pCO2)?
According to the information provided, where is hydrogen carbonate primarily formed from carbon dioxide?
According to the information provided, where is hydrogen carbonate primarily formed from carbon dioxide?
What key information does the Henderson-Hasselbalch equation provide?
What key information does the Henderson-Hasselbalch equation provide?
The Henderson-Hasselbalch equation allows calculation of the change to one of three variables if which other variables are known?
The Henderson-Hasselbalch equation allows calculation of the change to one of three variables if which other variables are known?
Which change would cause the pH to decrease?
Which change would cause the pH to decrease?
What does the pH of blood depend on?
What does the pH of blood depend on?
If you have a patient with a pKa of 6.1 and you know $PCO_2$ = 5kPa, and $[HCO_3^-]$ = 25mM, what is the approximate pH?
If you have a patient with a pKa of 6.1 and you know $PCO_2$ = 5kPa, and $[HCO_3^-]$ = 25mM, what is the approximate pH?
What is the typical ratio of [HCO3-] to dissolved CO2 in plasma?
What is the typical ratio of [HCO3-] to dissolved CO2 in plasma?
How does the effect of pCO2 changes influence the concentration of hydrogen carbonate in body fluids with few buffer systems?
How does the effect of pCO2 changes influence the concentration of hydrogen carbonate in body fluids with few buffer systems?
What is the function of carbonic anhydrase in red blood cells concerning carbon dioxide transport?
What is the function of carbonic anhydrase in red blood cells concerning carbon dioxide transport?
What is the role of hemoglobin in the red blood cells regarding the carbon dioxide reaction?
What is the role of hemoglobin in the red blood cells regarding the carbon dioxide reaction?
What happens to the hydrogen carbonate (HCO3-) formed in large quantities in the red blood cells?
What happens to the hydrogen carbonate (HCO3-) formed in large quantities in the red blood cells?
What primarily determines the concentration of HCO3- in the plasma?
What primarily determines the concentration of HCO3- in the plasma?
What two factors most directly determine the pH of body fluids?
What two factors most directly determine the pH of body fluids?
Besides its role in gas exchange, which organ plays a vital role in regulating [HCO3-] in the body?
Besides its role in gas exchange, which organ plays a vital role in regulating [HCO3-] in the body?
Under what condition is the normal pH balance (7.4) maintained?
Under what condition is the normal pH balance (7.4) maintained?
What affect does breathing have on arterial pCO2 and pH of body fluids?
What affect does breathing have on arterial pCO2 and pH of body fluids?
What compounds are formed when carbon dioxide reacts directly with the protein part of hemoglobin?
What compounds are formed when carbon dioxide reacts directly with the protein part of hemoglobin?
How does oxygenation of hemoglobin in the lungs affect its buffering capacity?
How does oxygenation of hemoglobin in the lungs affect its buffering capacity?
What happens to hydrogen ions in the lungs, and what does this form?
What happens to hydrogen ions in the lungs, and what does this form?
According to the context, what is the overall relationship between pCO2 and the content of CO2 in the blood?
According to the context, what is the overall relationship between pCO2 and the content of CO2 in the blood?
What consequence does a drop in alveolar pCO2 have on the pulmonary capillaries?
What consequence does a drop in alveolar pCO2 have on the pulmonary capillaries?
Why can hyperventilation reduce the $CO_2$ content in the blood, but cannot significantly increase the oxygen content?
Why can hyperventilation reduce the $CO_2$ content in the blood, but cannot significantly increase the oxygen content?
Which of the following equation describes the reaction of Carbon Dioxide and water?
Which of the following equation describes the reaction of Carbon Dioxide and water?
What is the overall reaction that happens during reverse chloride shift in lungs?
What is the overall reaction that happens during reverse chloride shift in lungs?
Flashcards
CO2 Transport Forms
CO2 Transport Forms
CO2 is transported in the blood predominantly as bicarbonate (60%), dissolved CO2 (10%), and carbaminohemoglobin (30%).
CO2 in Plasma
CO2 in Plasma
CO2 dissolves in plasma and can form hydrogen ions and hydrogen carbonate ions. The reaction in plasma is slow due to low carbonic anhydrase. Dissolved CO2 is directly proportional to pCO2.
Henderson-Hasselbalch Equation
Henderson-Hasselbalch Equation
The Henderson-Hasselbalch equation relates pH, bicarbonate concentration, and pCO2, allowing calculation of one if the other two are known, crucial for assessing acid-base status.
CO2 in Red Cells
CO2 in Red Cells
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[HCO3-] to CO2 Ratio in Plasma
[HCO3-] to CO2 Ratio in Plasma
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pH Determination
pH Determination
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Kidney's Role
Kidney's Role
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CO2 Dissociation Curve Shape
CO2 Dissociation Curve Shape
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Effect of Breathing
Effect of Breathing
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Arterial Blood
Arterial Blood
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Study Notes
Carbon Dioxide Reactions in Blood
- Carbon dioxide is transported in blood in three forms, HCO3- (60%), dissolved CO2 (10%) and Carbaminohemoglobin (30%).
Carbon Dioxide in Plasma
- Carbon dioxide dissolves in plasma, potentially forming hydrogen and hydrogen carbonate ions.
- The reaction in plasma is sluggish due to limited carbonic anhydrase.
- The amount of dissolved CO2 is proportional to pCO2.
- At a pCO2 of 5.3 kPa, dissolved CO2 concentration is 1.2 mmol/L.
- Hydrogen carbonate in plasma primarily comes from CO2 reactions in red blood cells.
Henderson-Hasselbalch Equation
- The Henderson-Hasselbalch equation enables calculating plasma pH if pCO2 and [HCO3-] values are known.
- The equation is important, as knowing any two variables (pH, [HCO3-], or pCO2) allows calculating the third.
- The equation is pH = pKa + log([HCO3-] / [CO2]).
- Under normal arterial blood conditions, pH is 7.40 and pK is 6.10.
- pKa is 6.1, expressing PCO2 in kPa using 0.23 as the CO2 solubility constant.
- Changes in pCO2 and [HCO3-] directly affect pH levels.
- An increase in PCO2 will result in a decrease in pH, while an increased [HCO3-] results in an increase in pH.
Carbon Dioxide in Red Blood Cells
- Carbon dioxide reacts with water in red blood cells, rapidly, because carbonic anhydrase is present.
- This forms H+ and HCO3-.Hydrogen ions bind to hemoglobin, enhanced when de-oxygenated.
- The reactions are CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3- and H+ + Hb- ↔ HbH.
Transportation and Chloride Shift
- HCO3- formed is exported from the red cells in exchange for Cl-.
- The kidney has an important role in controlling [HCO3-] in plasma.
- The pH of body fluids is determined by the relationship between CO2 dissolved in plasma and HCO3- formed from CO2 in red cells involving hemoglobin.
- Arterial pCO2, affected by breathing influences the pH of body fluids.
- The critical feature is that when there is 20 times as much HCO3- as dissolved CO2 in plasma the pH will be 7.4
- Ratio of HCO3- to pCO2 is important rather than absolute values is what important.
- Carbon dioxide reacts directly with protein part of hemoglobin to form carbamino compounds.
- Increased pCO2 causes more CO2 to dissolve and more carbamino compounds, around 10% more CO2 reacts in venous blood.
- Blood reaches the lungs the oxygenation of haemoglobin makes Hb a less capable buffer where hydrogen ions react with hydrogen carbonate to form CO2 which is exhaled.
Carbon Dioxide Dissociation Curve
- The 'carbon dioxide dissociation curve' has a straight slope, with a linear relationship between pCO2 and CO2 content in blood.
- When alveolar pCO2 reduces, pulmonary capillaries give up more CO2.
- Hyperventilation significantly reduces CO2 content in the blood, but doesn't significantly increase the oxygen content
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