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Questions and Answers
Questions and Answers
Which of the following conditions would cause a shift to the right in the oxygen-hemoglobin dissociation curve?
Which of the following conditions would cause a shift to the right in the oxygen-hemoglobin dissociation curve?
- Decreased temperature
- Decreased 2,3-DPG concentration
- Increased pH
- Increased PCO2 (correct)
What is the primary effect of a leftward shift in the oxygen-hemoglobin dissociation curve on oxygen delivery?
What is the primary effect of a leftward shift in the oxygen-hemoglobin dissociation curve on oxygen delivery?
- Facilitates oxygen unloading in the tissues.
- Has no effect on oxygen delivery.
- Impairs oxygen unloading in the tissues. (correct)
- Increases the amount of oxygen bound to hemoglobin
How does a decrease in pH affect the affinity of hemoglobin for oxygen?
How does a decrease in pH affect the affinity of hemoglobin for oxygen?
- Stabilizes the hemoglobin molecule.
- Decreases the affinity, causing a rightward shift. (correct)
- Increases the affinity, causing a leftward shift.
- Has no effect on the affinity.
What is the normal alveolar pCO2?
What is the normal alveolar pCO2?
Which of the following changes would likely cause a shift in the oxygen-hemoglobin dissociation curve, facilitating increased oxygen delivery to tissues during exercise?
Which of the following changes would likely cause a shift in the oxygen-hemoglobin dissociation curve, facilitating increased oxygen delivery to tissues during exercise?
What is the approximate percentage of oxygen transported in the blood by combining with hemoglobin?
What is the approximate percentage of oxygen transported in the blood by combining with hemoglobin?
Which of the following factors does not directly increase the affinity of hemoglobin for oxygen, shifting the oxygen-hemoglobin dissociation curve to the left?
Which of the following factors does not directly increase the affinity of hemoglobin for oxygen, shifting the oxygen-hemoglobin dissociation curve to the left?
If each gram of hemoglobin binds to 1.34 ml of $O_2$, approximately how much $O_2$ can 15 grams of hemoglobin carry at 100% saturation?
If each gram of hemoglobin binds to 1.34 ml of $O_2$, approximately how much $O_2$ can 15 grams of hemoglobin carry at 100% saturation?
Why is dissolved oxygen alone insufficient to meet human tissue requirements?
Why is dissolved oxygen alone insufficient to meet human tissue requirements?
What does a rightward shift in the oxygen-hemoglobin dissociation curve indicate?
What does a rightward shift in the oxygen-hemoglobin dissociation curve indicate?
Under normal physiological conditions, what is the approximate partial pressure of oxygen ($pO_2$) in venous blood?
Under normal physiological conditions, what is the approximate partial pressure of oxygen ($pO_2$) in venous blood?
How does temperature affect the oxygen-hemoglobin dissociation curve?
How does temperature affect the oxygen-hemoglobin dissociation curve?
What is the approximate solubility coefficient of $O_2$ in body fluids at 37°C?
What is the approximate solubility coefficient of $O_2$ in body fluids at 37°C?
What is the primary factor for the exchange of gases across the alveolar membrane?
What is the primary factor for the exchange of gases across the alveolar membrane?
How much faster does CO2 diffuse in comparison to oxygen across the alveolar membrane?
How much faster does CO2 diffuse in comparison to oxygen across the alveolar membrane?
What determines the diffusion rate of gases in the alveoli?
What determines the diffusion rate of gases in the alveoli?
What is the typical time required for full gas exchange in the alveolar capillaries?
What is the typical time required for full gas exchange in the alveolar capillaries?
What is measured to estimate the diffusion capacity of the lungs?
What is measured to estimate the diffusion capacity of the lungs?
How is the diffusion capacity of the lung assessed during the TLCO test?
How is the diffusion capacity of the lung assessed during the TLCO test?
What does the measurement of alveolar pCO2 help determine?
What does the measurement of alveolar pCO2 help determine?
Why is carbon monoxide ideal for assessing lung diffusion capacity?
Why is carbon monoxide ideal for assessing lung diffusion capacity?
Questions and Answers
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Flashcards
Flashcards
Oxyhemoglobin Dissociation Curve
Oxyhemoglobin Dissociation Curve
Graph showing the relationship between oxygen and hemoglobin binding.
Right Shift of Curve
Right Shift of Curve
Occurs when hemoglobin's affinity for O2 decreases, facilitating O2 unloading.
Left Shift of Curve
Left Shift of Curve
Occurs when hemoglobin's affinity for O2 increases, making O2 unloading harder.
Bohr Effect
Bohr Effect
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2,3-DPG Role
2,3-DPG Role
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Solubility of Oxygen
Solubility of Oxygen
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Oxygen Transport Forms
Oxygen Transport Forms
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O2 Binding Capacity of Hb
O2 Binding Capacity of Hb
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Influencing Factors
Influencing Factors
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Alveolar pO2 Value
Alveolar pO2 Value
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Capillary pO2 in Tissues
Capillary pO2 in Tissues
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Oxygen Delivery to Tissues
Oxygen Delivery to Tissues
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Gas Exchange
Gas Exchange
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Partial Pressure Gradients
Partial Pressure Gradients
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Diffusion Rates
Diffusion Rates
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Diffusion Capacity (TLCO)
Diffusion Capacity (TLCO)
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Alveolar Gas Composition
Alveolar Gas Composition
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Alveolar pCO2 and pO2
Alveolar pCO2 and pO2
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Diffusion Resistance
Diffusion Resistance
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Carbon Monoxide Uptake
Carbon Monoxide Uptake
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Study Notes
Study Notes
Respiratory Module: Blood Gas Carriage
- Objectives:
- State the solubility of oxygen in body fluids.
- Draw an oxygen-hemoglobin dissociation curve, labeling the axes and indicating normal alveolar pO2, capillary pO2 in typical tissue.
- Draw the effects of pH and temperature on the hemoglobin oxygen dissociation curve.
- State factors influencing gas diffusion across the alveolar membrane.
- Outline how the transfer factor (diffusion capacity) of the lungs is determined.
- Estimate the rate of oxygen delivery to tissues given varying capillary pO2 and pH.
Solubility of Oxygen
- Oxygen is not highly soluble in body fluids.
- Solubility coefficient of O2 = 0.01 mmol/L/kPa at 37°C.
- At a partial pressure of 13.3 kPa and 37°C, plasma contains 0.13 mmol/L of dissolved oxygen.
Oxygen Transport
- Oxygen is carried in the blood in two forms: dissolved and combined with hemoglobin (Hb).
- Most oxygen (97%) is transported bound to hemoglobin, significantly increasing oxygen-carrying capacity.
- Only 3% is dissolved.
- Partial pressure of O2 in blood leaving the lung is 95 mmHg (97% saturation).
- Venous blood contains 40 mmHg (75% saturation).
- Each gram of Hb binds to 1.34 mL O2.
- 100% saturated blood carries 20.1 mL O2 per 100 mL of blood.
- Blood leaving the lungs carries 19.4 mL O2 per 100 mL.
- In tissues, oxygen saturation is 40%, and venous blood carries 14.4 mL O2 per 100 mL.
Oxygen-Hemoglobin Dissociation Curve
- A graphical representation of oxygen saturation (%) at different PO2 levels.
- Sigmoidal (S-shaped) curve reflects hemoglobin's cooperative binding with oxygen.
- Loading and unloading of oxygen.
- Steep portion: small changes in PO2 result in large changes in saturation. More oxygen is unloaded at lower PO2 values.
- Factors affecting the curve:
- Decreasing pH, increasing temperature, and increasing 2,3-diphosphoglycerate (DPG) concentration cause a rightward shift in the curve. This promotes oxygen unloading in tissues.
- Increasing pH, decreasing temperature, and decreasing DPG concentration cause a leftward shift in the curve, making oxygen unloading from hemoglobin more difficult.
Carbon Dioxide Transport
- Most CO2 travels in the blood as bicarbonate ions (HCO3−).
- CO2 is released from its gaseous form in the alveoli.
Carbon Monoxide Transfer Factor (TLCO)
- Estimates the resistance to diffusion across the alveolar membrane.
- Subject inhales a gas mixture with 14% helium and 0.1% carbon monoxide.
- Helium and CO in exhaled air are measured to determine diffusion capacity.
Diseases Affecting Diffusion
- Thickening or destruction of the alveolar walls affect the transfer factor.
- Conditions such as interstitial lung disease and pulmonary edema result in lower-than-normal TLCO.
- Emphysema lowers the diffusion area, decreasing the TLCO value.
Bohr Effect
- Unloading is further aided by the Bohr effect (lower pH in tissues reduces hemoglobin's affinity for oxygen).
- Temperature increase has a similar effect.
Mixed Venous Blood/Alveolar Air Comparison
- Blood entering the lungs (mixed venous blood) has a relatively lower pO2 and higher pCO2 than the alveolar air.
- These partial pressure gradients facilitate gas exchange in the lungs.
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