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Questions and Answers
What best describes the solubility of oxygen in body fluids at a partial pressure of 13.3 kPa and a temperature of 37°C?
What best describes the solubility of oxygen in body fluids at a partial pressure of 13.3 kPa and a temperature of 37°C?
- Oxygen is highly soluble, ensuring efficient gas transport.
- Plasma contains 0.13 mmol/L of dissolved oxygen. (correct)
- Plasma contains 0.01 mmol/L of dissolved oxygen.
- The solubility coefficient of $O_2$ is 1.33 mmol/L /kPa.
In what two forms is oxygen primarily carried in the blood?
In what two forms is oxygen primarily carried in the blood?
- Bound to bicarbonate ions and dissolved in plasma
- Dissolved and combined with haemoglobin (correct)
- Chemically altered and dissolved in plasma
- Attached to red blood cell membranes and dissolved
What percentage relates to the amount of $O_2$ in the blood that is transported by combining with hemoglobin?
What percentage relates to the amount of $O_2$ in the blood that is transported by combining with hemoglobin?
- 97% (correct)
- 50%
- 75%
- 3%
What is the approximate partial pressure of $O_2$ in blood leaving the lung and in venous blood?
What is the approximate partial pressure of $O_2$ in blood leaving the lung and in venous blood?
How much $O_2$ does each gram of Hb bind when fully saturated, and approximately how much $O_2$ is carried in 100ml of blood at 97% saturation?
How much $O_2$ does each gram of Hb bind when fully saturated, and approximately how much $O_2$ is carried in 100ml of blood at 97% saturation?
How much oxygen can dissolved oxygen deliver to the tissues and what is required?
How much oxygen can dissolved oxygen deliver to the tissues and what is required?
Which of the following axes are typically used to represent the oxygen-hemoglobin dissociation curve?
Which of the following axes are typically used to represent the oxygen-hemoglobin dissociation curve?
What effect do decreased pH, increased temperature, and increased 2,3-DPG have on the affinity of hemoglobin for oxygen?
What effect do decreased pH, increased temperature, and increased 2,3-DPG have on the affinity of hemoglobin for oxygen?
Which statement accurately describes the impact of the sigmoidal shape of the oxygen-hemoglobin dissociation curve on oxygen delivery to tissues?
Which statement accurately describes the impact of the sigmoidal shape of the oxygen-hemoglobin dissociation curve on oxygen delivery to tissues?
What does a rightward shift of the oxygen-hemoglobin dissociation curve indicate?
What does a rightward shift of the oxygen-hemoglobin dissociation curve indicate?
An individual is exercising strenuously. Which of the following changes in their blood would promote the unloading of oxygen from hemoglobin in the tissues?
An individual is exercising strenuously. Which of the following changes in their blood would promote the unloading of oxygen from hemoglobin in the tissues?
How does carbon dioxide ($CO_2$) diffuse across the alveolar membrane compared to oxygen ($O_2$)?
How does carbon dioxide ($CO_2$) diffuse across the alveolar membrane compared to oxygen ($O_2$)?
Consider a scenario where a patient's hemoglobin has a decreased affinity for oxygen. Which of the following sets of conditions would most likely cause this?
Consider a scenario where a patient's hemoglobin has a decreased affinity for oxygen. Which of the following sets of conditions would most likely cause this?
How does the body adjust to ensure adequate oxygen delivery under conditions that shift the oxygen-hemoglobin dissociation curve to the right?
How does the body adjust to ensure adequate oxygen delivery under conditions that shift the oxygen-hemoglobin dissociation curve to the right?
What is the normal alveolar $pO_2$ and alveolar $pCO_2$?
What is the normal alveolar $pO_2$ and alveolar $pCO_2$?
What term describes the phenomenon where the affinity of hemoglobin for oxygen is reduced by lower pH in the tissues, facilitating oxygen unloading?
What term describes the phenomenon where the affinity of hemoglobin for oxygen is reduced by lower pH in the tissues, facilitating oxygen unloading?
What is the primary purpose of measuring the carbon monoxide transfer factor (TLCO)?
What is the primary purpose of measuring the carbon monoxide transfer factor (TLCO)?
In the TLCO test, why is carbon monoxide (CO) used instead of oxygen?
In the TLCO test, why is carbon monoxide (CO) used instead of oxygen?
In a TLCO test, which gas is used to correct for the diluting effects of air within the lungs?
In a TLCO test, which gas is used to correct for the diluting effects of air within the lungs?
In the context of pulmonary function testing, what does a low TLCO typically indicate?
In the context of pulmonary function testing, what does a low TLCO typically indicate?
What specific steps are involved in the measurement of TLCO?
What specific steps are involved in the measurement of TLCO?
A patient has a pulmonary embolism that blocks blood flow to a portion of their lung. How would this condition likely affect their TLCO, and why?
A patient has a pulmonary embolism that blocks blood flow to a portion of their lung. How would this condition likely affect their TLCO, and why?
In a patient with severe emphysema, what is the most direct mechanism by which the disease reduces the TLCO?
In a patient with severe emphysema, what is the most direct mechanism by which the disease reduces the TLCO?
What is likely to happen to a patient's TLCO at high altitude and why?
What is likely to happen to a patient's TLCO at high altitude and why?
How does the use of helium in TLCO measurements help ensure the accuracy of the test results?
How does the use of helium in TLCO measurements help ensure the accuracy of the test results?
How exactly does the measurement of the carbon monoxide transfer factor (TLCO) provide insight into the condition of the alveolar-capillary membrane?
How exactly does the measurement of the carbon monoxide transfer factor (TLCO) provide insight into the condition of the alveolar-capillary membrane?
Which of the following adjustments would be necessary when performing a TLCO test on a patient with severe anemia?
Which of the following adjustments would be necessary when performing a TLCO test on a patient with severe anemia?
In the context of oxygen transport, what compensatory mechanism does the body employ to counteract a leftward shift of the oxygen-hemoglobin dissociation curve?
In the context of oxygen transport, what compensatory mechanism does the body employ to counteract a leftward shift of the oxygen-hemoglobin dissociation curve?
A patient with chronic kidney disease often presents with metabolic acidosis. How might this condition affect the oxygen-hemoglobin dissociation curve and oxygen delivery to tissues?
A patient with chronic kidney disease often presents with metabolic acidosis. How might this condition affect the oxygen-hemoglobin dissociation curve and oxygen delivery to tissues?
Which of the following individuals would likely have the highest concentration of 2,3-diphosphoglycerate (2,3-DPG) in their red blood cells?
Which of the following individuals would likely have the highest concentration of 2,3-diphosphoglycerate (2,3-DPG) in their red blood cells?
What best describes a key difference between hemoglobin and myoglobin dissociation curves?
What best describes a key difference between hemoglobin and myoglobin dissociation curves?
What adaptation might be expected in individuals who are long-term residents at high altitudes, concerning their oxygen transport?
What adaptation might be expected in individuals who are long-term residents at high altitudes, concerning their oxygen transport?
How does the body prioritize oxygen delivery to different tissues during periods of increased demand, such as during exercise?
How does the body prioritize oxygen delivery to different tissues during periods of increased demand, such as during exercise?
What is the role of ventilation in maintaining the difference in gas composition between alveolar air and mixed venous blood?
What is the role of ventilation in maintaining the difference in gas composition between alveolar air and mixed venous blood?
How does the presence of interstitial lung diseases or pulmonary edema affect the TLCO?
How does the presence of interstitial lung diseases or pulmonary edema affect the TLCO?
What aspect of alveolar and blood physiology primarily determines the rate of gas exchange, assuming normal conditions?
What aspect of alveolar and blood physiology primarily determines the rate of gas exchange, assuming normal conditions?
How does the affinity of hemoglobin for oxygen change after initial binding, and what is the significance of this change for oxygen transport?
How does the affinity of hemoglobin for oxygen change after initial binding, and what is the significance of this change for oxygen transport?
Flashcards
Oxygen solubility in body fluids
Oxygen solubility in body fluids
The amount of oxygen that can dissolve in body fluids is limited. It is not enough for adequate gas transport on its own.
Oxygen Bound to Hemoglobin
Oxygen Bound to Hemoglobin
Most oxygen in the blood is bound to hemoglobin, greatly increasing the blood's oxygen-carrying capacity.
Oxygen Saturation in Arterial Blood
Oxygen Saturation in Arterial Blood
The partial pressure of oxygen in blood leaving the lungs is about 95 mmHg, resulting in 97% hemoglobin saturation.
Oxygen Saturation in Venous Blood
Oxygen Saturation in Venous Blood
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Oxygen Binding to Hemoglobin
Oxygen Binding to Hemoglobin
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Oxyhemoglobin Dissociation Curve
Oxyhemoglobin Dissociation Curve
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Steep Portion Significance
Steep Portion Significance
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Effect of decreased pH and increased temp on hemoglibin affinity
Effect of decreased pH and increased temp on hemoglibin affinity
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Factors Causing Right Shift
Factors Causing Right Shift
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Factors Causing Left Shift
Factors Causing Left Shift
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What is the Bohr Shift?
What is the Bohr Shift?
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Normal Alveolar Gas Pressures
Normal Alveolar Gas Pressures
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Alveolar-Capillary Gas Equilibrium
Alveolar-Capillary Gas Equilibrium
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Carbon Monoxide Transfer Factor (TLCO)
Carbon Monoxide Transfer Factor (TLCO)
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TLCO Measurement Process
TLCO Measurement Process
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Impact of Alveolar Wall Thickening on TLCO
Impact of Alveolar Wall Thickening on TLCO
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Study Notes
Oxygen Solubility in Body Fluids
- Oxygen's solubility in body fluids alone isn't adequate for sufficient gas transport.
- The solubility coefficient of O₂ is 0.01 mmol/L/kPa at 37°C.
- In plasma at 37°C with a partial pressure of 13.3 kPa, dissolved oxygen is at 0.13 mmol/L (0.01 x 13.3).
Oxygen Transport
- Oxygen is transported in blood in two forms: dissolved and combined with hemoglobin (Hb).
- Combining with Hb increases oxygen carrying capacity by 50x.
- 97% of Oâ‚‚ is transported via hemoglobin, while only 3% is dissolved.
- The partial pressure of Oâ‚‚ in blood leaving the lungs is 95mmHg, resulting in 97% saturation.
- Venous blood contains 40mmHg of Oâ‚‚, which is 75% saturation.
- Each gram of Hb binds to 1.34ml of Oâ‚‚; therefore, 1.34 x 15gm = 20.1ml Oâ‚‚ at 100% saturation.
- Blood with 95 mmHg (97% saturation) carries 19.4 ml Oâ‚‚.
- In tissues, the saturation is 40%, and in veins, it is 75%, carrying 14.4ml Oâ‚‚ in each 100ml of blood.
- Dissolved oxygen delivers only about 90 ml/min to the tissues.
- Tissue requirements are approximately 3000 ml Oxygen/min, dissolved Oâ‚‚ alone not adequate for the human body.
Oxygen-Hemoglobin Dissociation Curve
- Graphically represents the percentage of oxyhemoglobin saturation at varying partial pressure of oxygen (POâ‚‚).
- Illustrates oxygen loading and unloading.
- The steep portion of the sigmoidal curve means small POâ‚‚ changes can result in significant saturation differences, facilitating greater oxygen unloading.
- A decrease in pH, increase in temperature causes decreased affinity of hemoglobin for Oâ‚‚, which leads to more unloading of oxygen.
- The curve shifts to the right, decreasing hemoglobin's affinity for oxygen.
Factors Shifting the Oxygen-Hemoglobin Dissociation Curve to the Right
- Decreased affinity of Hb for Oâ‚‚ facilitates oxygen unloading in tissues.
- Increased PCOâ‚‚ and decreased pH.
- Increased temperature.
- Elevated levels of 2,3-diphosphoglycerate (2,3-DPG).
- HbO₂ + 2,3 DPG → Hb-2,3 DPG + O₂
Factors Shifting the Oxygen-Hemoglobin Dissociation Curve to the Left
- This happens when the affinity of Hb for oxygen increases which makes unloading of Oâ‚‚ in tissue more difficult.
- Decrease in PCOâ‚‚ and increases in pH
- Decreases in temperature
- Decrease in 2,3-DPG concentration
Bohr Shift
- Oxygen unloading is enhanced.
- Hemoglobin's affinity for oxygen is reduced by lower pH levels in the tissues.
Gas Exchange and Ventilation
- The alveolar pOâ‚‚ is normally 13.3 kPa.
- The Alveolar pCOâ‚‚ is normally 5.3 kPa.
- Gas exchange across the alveolar membrane relies on partial pressure gradients between alveolar gas and blood returning from the body.
- Oxygen diffuses more rapidly in the gas phase, but COâ‚‚ diffuses more rapidly in the liquid phase. Overall, COâ‚‚ diffuses 21 times faster than oxygen.
- Blood leaving the alveolar capillaries has the same gaseous composition as alveolar air.
- Arterial gas tensions depend on alveolar gas composition.
- Respiration is controlled to keep alveolar pCOâ‚‚ at 5.3 kPa and alveolar pOâ‚‚ at 13.3 kPa.
Diffusion Rate Factors
- Structure of the alveolar membrane, the extracellular fluid barrier, and the capillary wall influences diffusion.
- Diffusion happens quickly, allowing full gas exchange in about 500 ms which is half the time blood is within the capillaries.
Carbon Monoxide Transfer Factor (TLCO)
- Assesses the diffusion capacity across the alveolar membrane.
- TLCO = Transfer Factor of the Lung for Carbon Monoxide
- The process involves taking a single vital capacity breath of a testing gas.
- testing gas includes air, 14% Helium, and 0.1% Carbon monoxide
- The breath is held, followed by an exhalation where the first 750 ml is discarded.
- The following litre is collected to measure helium and CO levels.
- The quantity of CO transferred from alveoli to blood estimates lung diffusion capacity, unaffected by blood flow rate.
- Alveolar pCO and CO uptake are measured to calculate the "Transfer Factor".
- Helium corrects for air dilution in the lungs during measurement.
Diseases Affecting Diffusion (Low TLCO)
- Issues such as increased distance for gas travel from alveolus to blood.
- Thickening of the space between blood and gas (gas barrier).
- These can stem from diseases like Interstitial lung diseases and pulmonary edema.
- Alveolar wall destruction, as seen in emphysema, reduces available diffusion area and lowers the CO transfer factor.
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