Exam 3: 25 Mar Pulmonary Function Tests and Blood Gas Physiology Flashcards
What are pulmonary function tests used for?
To assess lung function and generate flow-volume loops
They capture data that can be plotted in various ways for interpretation.
What is the solubility coefficient of oxygen in blood?
0.003 ml of O2 per mmHg PO2
This means that for every mmHg of partial pressure of oxygen, 0.003 ml can dissolve in blood.
How much oxygen does hemoglobin carry per gram?
1.34 ml of O2 per gram
This indicates the capacity of hemoglobin to transport oxygen in the blood.
What is the normal arterial oxygen content in blood?
20.1 ml/dL
This value represents the amount of oxygen carried in the arterial blood.
How does fetal hemoglobin differ from adult hemoglobin?
Fetal hemoglobin has a higher affinity for oxygen
This allows fetuses to extract oxygen from maternal blood more efficiently.
What form of carbon dioxide is primarily transported in blood?
Bicarbonate (90%)
CO2 is also transported in dissolved and carbamino forms.
What is the typical oxygen saturation of venous blood?
70-75%
This is lower than arterial blood saturation.
What is the impact of pH on the oxygen-hemoglobin dissociation curve?
Changes in pH affect hemoglobin’s affinity for oxygen
A lower pH (more acidic) decreases affinity, shifting the curve to the right.
What is the solubility coefficient of carbon dioxide in blood?
0.06 ml of CO2 per mmHg
This indicates how much CO2 can dissolve in blood based on its partial pressure.
What is the relationship between hemoglobin oxygenation and CO2 transport?
Deoxygenated blood carries more CO2
This is due to the Bohr effect, where increased CO2 enhances oxygen release.
How do temperature changes affect oxygen binding to hemoglobin?
Higher temperatures decrease oxygen binding affinity
This makes it more difficult for hemoglobin to hold onto oxygen.
What is the calculation for determining dissolved oxygen in blood?
PO2 (mmHg) x solubility coefficient
The solubility coefficient for oxygen is 0.003 ml/mmHg.
What is the role of carbonic anhydrase in CO2 transport?
Facilitates conversion of CO2 to bicarbonate
This reaction helps maintain acid-base balance in the blood.
What happens to hemoglobin saturation at low hemoglobin levels?
It decreases the total oxygen content
For example, at 10% saturation, only 2 ml of O2 can be carried.
Fill in the blank: The dissolved oxygen in blood cannot meet the metabolic demand of __________ ml O2 each minute.
250
This illustrates the importance of hemoglobin in oxygen transport.
True or False: Venous blood has a higher oxygen saturation than arterial blood.
False
Arterial blood has a higher oxygen saturation than venous blood.
What are the three forms of carbon dioxide in blood?
- Dissolved
- Carbamino
- Bicarbonate
These forms play a crucial role in CO2 transport and acid-base balance.
What does 100% saturation of hemoglobin indicate?
All binding spots on hemoglobin are occupied by oxygen
If hemoglobin is at 10% saturation with 15 grams of hemoglobin, how much oxygen is bound?
2 mL of O2
What two factors are needed to determine how much oxygen is bound to hemoglobin?
- Carrying capacity of hemoglobin
- Hemoglobin oxygen saturation percentage
What is the normal hemoglobin level in a healthy adult?
15 grams
What is the structural composition of adult hemoglobin?
- 2 alpha subunits
- 2 beta subunits
What type of hemoglobin is found in fetuses?
Fetal hemoglobin
What is the difference in subunit composition between fetal hemoglobin and adult hemoglobin?
- Fetal hemoglobin has gamma subunits instead of beta subunits
Why does fetal hemoglobin have a higher affinity for oxygen than adult hemoglobin?
To extract oxygen from maternal blood
What regulates the production of hemoglobin in the body?
Erythropoietin from the kidneys
What is myoglobin and how does it differ from hemoglobin?
Myoglobin is structurally similar to hemoglobin but has a higher affinity for oxygen
What is the role of myoglobin in muscle tissue?
Helps oxygen unload into muscles that need it
What happens to the oxygen content in a sample if hemoglobin is bound with carbon monoxide?
Oxygen carrying capacity is reduced
What is the oxyhemoglobin dissociation curve?
A graph showing the relationship between hemoglobin saturation and oxygen partial pressure
What does a leftward shift in the oxyhemoglobin dissociation curve indicate?
Increased affinity of hemoglobin for oxygen
What is the effect of carbon monoxide on hemoglobin’s affinity for oxygen?
Increases the affinity, making it harder for oxygen to be released
What is the normal arterial oxygen saturation percentage in healthy individuals?
Approximately 97.4%
What is the typical venous oxygen saturation percentage?
About 75%
Why does the coronary circulation have a lower venous hemoglobin saturation than other circulatory beds?
The heart extracts about 75% of the oxygen from the blood
What happens to hemoglobin saturation when the kidneys are not functioning properly?
Erythropoietin may be administered to maintain hemoglobin production
What is the significance of iron in hemoglobin and myoglobin?
Iron is the component that binds oxygen
Fill in the blank: The oxygen content in blood is the sum of the _______ and _______.
[dissolved state], [bound state]
True or False: Myoglobin is found in all muscles.
False
What is the saturation percentage of oxygen in normal venous blood?
About 75% saturated
This percentage may be slightly lower due to acidity and CO2 levels in venous blood.
How does fetal hemoglobin differ from adult hemoglobin in terms of oxygen affinity?
Fetal hemoglobin has a higher affinity for oxygen
This is represented by a left shift in the oxyhemoglobin dissociation curve.
What happens to hemoglobin saturation as PO2 increases?
Hemoglobin saturation increases
More oxygen in solution leads to higher PO2, allowing more oxygen to bind to hemoglobin.
At what PO2 is fetal hemoglobin approximately 50% saturated?
Around 18 mmHg
This indicates a lower PO2 requirement for saturation compared to adult hemoglobin.
What effect does increased CO2 have on hemoglobin’s oxygen affinity?
It causes a right shift in the dissociation curve
This means that oxygen is more prone to being released from hemoglobin.
What is the Bohr effect?
The phenomenon where increased CO2 and acidity lead to decreased hemoglobin affinity for oxygen
This facilitates oxygen unloading in metabolically active tissues.
What is the effect of pH on hemoglobin’s affinity for oxygen?
Lower pH (more acidic) decreases affinity; higher pH increases affinity
This results in right shifts and left shifts of the dissociation curve, respectively.
What is 2,3-BPG’s role in oxygen unloading?
It promotes oxygen unloading by shifting the dissociation curve to the right
Increased levels of 2,3-BPG facilitate oxygen release from hemoglobin.
How does temperature affect hemoglobin’s affinity for oxygen?
Higher temperatures decrease affinity; lower temperatures increase affinity
This helps oxygen unloading in metabolically active tissues where temperatures are usually higher.
What is the approximate oxygen content in arterial blood with a PO2 of 100 mmHg?
About 20 mL O2 per deciliter of blood
This high content is due to the high saturation of hemoglobin at this PO2.
What is the oxygen content in venous blood with a PO2 of 40 mmHg?
About 15 mL O2 per deciliter of blood
This indicates that approximately a quarter of the oxygen has been released to tissues.
True or False: Adult hemoglobin requires a higher PO2 to achieve 50% saturation compared to fetal hemoglobin.
True
Adult hemoglobin has a lower affinity for oxygen, requiring higher PO2 for saturation.
Fill in the blank: The _______ effect describes how increased CO2 and decreased pH lead to oxygen unloading from hemoglobin.
Bohr
This effect is crucial for oxygen delivery in metabolically active tissues.
What two processes are involved in oxygen loading and unloading in the lungs?
Oxygen unlocking and oxygen loading
What happens to oxygenation when a person has a high fever?
Oxygenation becomes more difficult
How does fetal hemoglobin compare to maternal adult hemoglobin in terms of oxygen affinity?
Fetal hemoglobin has a higher affinity for oxygen
What is the typical venous hemoglobin saturation in healthy individuals?
Approximately 70%
What does a lower pH in venous blood indicate?
Higher PCO2 and reduced oxygen saturation
What is the P50 value?
The partial pressure of oxygen required to achieve 50% hemoglobin saturation
What is the normal P50 value for healthy hemoglobin?
26.5 mmHg
What are the three forms in which CO2 is transported in the blood?
- Dissolved CO2
- Carbamino compounds
- Bicarbonate (HCO3-)
What percentage of CO2 in the blood is typically transported as bicarbonate?
Approximately 90%
How do you calculate the amount of dissolved CO2 in the blood?
Multiply the solubility of CO2 by its partial pressure
What is the solubility of CO2 in blood?
0.06 mL CO2 per mmHg PCO2 per deciliter of blood
What happens to carbonic acid in conditions with high CO2 levels?
It dissociates into bicarbonate and protons
What enzyme facilitates the conversion of carbonic acid to CO2 and water?
Carbonic anhydrase
How does the presence of CO2 affect the direction of the bicarbonate reaction?
High CO2 promotes the formation of bicarbonate; low CO2 reverses the reaction
What is the typical composition of CO2 transport in arterial blood?
- 5% dissolved
- 5% as carbamino compounds
- 90% as bicarbonate
True or False: Venous blood has a higher proportion of dissolved CO2 compared to arterial blood.
True
What is the impact of acidosis on hemoglobin saturation?
It typically lowers hemoglobin saturation
What is the relationship between oxygen affinity and P50 value?
Lower affinity increases P50 value; higher affinity decreases it
What is the typical PCO2 level in arterial blood?
40 mmHg
What is the typical PCO2 level in venous blood?
45 mmHg
What role do terminal amine groups play in CO2 transport?
They can bind CO2 to form carbamino compounds
How does the CO2 dissociation curve differ from the O2 dissociation curve?
The CO2 curve has a different shape and includes three forms of CO2 transport
What is the expected venous hemoglobin saturation in critically ill patients?
Substantially lower than 70%
What are the three forms of CO2 in the blood?
- Dissolved CO2
- Carbamino compounds
- Bicarbonate (HCO3−)
These three forms are crucial for understanding CO2 transport in the blood.
What percentage of total CO2 is typically dissolved in the blood?
5%
This is based on the example of 2.4 mL of dissolved CO2 per deciliter of blood.
What is the typical CO2 content in arterial blood?
48 mL of CO2 per deciliter of blood
This value is derived from the calculations based on the distribution of CO2 forms.
What is the oxyhemoglobin saturation percentage in arterial blood?
97.5%
This saturation level indicates a high level of oxygen in arterial blood.
What is the typical PCO2 level in arterial blood?
40 mmHg
This value is essential for understanding the acid-base balance in the blood.
What is the CO2 content in venous blood?
52.5 mL of CO2 per deciliter of blood
Venous blood has a higher CO2 content due to lower oxygen saturation.
What is the oxyhemoglobin saturation percentage in venous blood?
Approximately 70%
This lower saturation indicates less oxygen is available in venous blood.
True or False: Deoxygenated hemoglobin can carry more CO2 than oxygenated hemoglobin.
True
Deoxygenated hemoglobin has a higher affinity for CO2.
Fill in the blank: The three functions of hemoglobin include binding/releasing oxygen, forming ________, and buffering protons.
carbamino compounds
These functions illustrate the versatility of hemoglobin in gas transport.
What factor affects the carrying capacity of blood for CO2?
Hemoglobin oxygenation
The saturation level of hemoglobin influences how much CO2 can be carried.
What happens to the CO2 carrying capacity when hemoglobin is saturated with oxygen?
It decreases
Less room for CO2 transport occurs when more oxygen is present.
What does a shift in the CO2 dissociation curve indicate?
Changes in hemoglobin oxygenation status
Shifts can indicate different physiological conditions affecting CO2 transport.
How does the presence of protons affect the CO2 transport in blood?
It facilitates the conversion of CO2 into bicarbonate
This buffering action helps maintain pH balance in the blood.
What is the relationship between CO2 content and oxygen saturation in the blood?
Inverse relationship
As oxygen saturation increases, CO2 content tends to decrease.
What is the significance of calculating CO2 content in blood?
It helps understand respiratory and metabolic functions
Accurate calculations are crucial for diagnosing and managing various medical conditions.
What role does hemoglobin play in buffering protons?
Hemoglobin can bind to protons, thus reducing acidity
This buffering capacity is essential for maintaining blood pH.
