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Questions and Answers
What is needed for oxygen to dissolve in liquid as compared to carbon dioxide?
What is needed for oxygen to dissolve in liquid as compared to carbon dioxide?
How much oxygen transport in the blood is bound to hemoglobin?
How much oxygen transport in the blood is bound to hemoglobin?
What happens to hemoglobin when the partial pressure of oxygen (pO2) is low?
What happens to hemoglobin when the partial pressure of oxygen (pO2) is low?
Which factor increases the oxygen carrying capacity of hemoglobin?
Which factor increases the oxygen carrying capacity of hemoglobin?
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What effect does an increase in temperature have on the oxyhemoglobin saturation curve?
What effect does an increase in temperature have on the oxyhemoglobin saturation curve?
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Which condition is associated with an increase in 2,3-BPG inside red blood cells?
Which condition is associated with an increase in 2,3-BPG inside red blood cells?
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What describes the relationship between plasma pO2 and the amount of oxygen that binds to hemoglobin?
What describes the relationship between plasma pO2 and the amount of oxygen that binds to hemoglobin?
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What is a physiological effect of lower pH on hemoglobin's binding to oxygen?
What is a physiological effect of lower pH on hemoglobin's binding to oxygen?
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What are the three arterial blood parameters that influence ventilation?
What are the three arterial blood parameters that influence ventilation?
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Which of the following represents the partial pressure of carbon dioxide (PCO2) in arterial blood under normal conditions?
Which of the following represents the partial pressure of carbon dioxide (PCO2) in arterial blood under normal conditions?
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How does diffusion rate relate to the factors involved in gas exchange?
How does diffusion rate relate to the factors involved in gas exchange?
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Which gas has a higher solubility in water compared to air, affecting its concentration and partial pressure relationship?
Which gas has a higher solubility in water compared to air, affecting its concentration and partial pressure relationship?
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What does equilibrium between a gas in solution and its partial pressure depend on?
What does equilibrium between a gas in solution and its partial pressure depend on?
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What percentage of carbon dioxide is carried in venous blood as bicarbonate ion?
What percentage of carbon dioxide is carried in venous blood as bicarbonate ion?
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Which group is primarily responsible for the muscles of inspiration?
Which group is primarily responsible for the muscles of inspiration?
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How do peripheral chemoreceptors respond when oxygen levels are low?
How do peripheral chemoreceptors respond when oxygen levels are low?
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What is the primary role of central chemoreceptors?
What is the primary role of central chemoreceptors?
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What percentage of carbon dioxide is transported in venous blood as carbaminohemoglobin?
What percentage of carbon dioxide is transported in venous blood as carbaminohemoglobin?
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What occurs during expiration according to the current model of breathing control?
What occurs during expiration according to the current model of breathing control?
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Which cells in peripheral chemoreceptors are responsible for sensing changes in pO2, pH, and pCO2?
Which cells in peripheral chemoreceptors are responsible for sensing changes in pO2, pH, and pCO2?
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What triggers the abrupt shutdown of inspiratory neuron activity?
What triggers the abrupt shutdown of inspiratory neuron activity?
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Study Notes
Gas Exchange in the Lungs and Tissues
- Three regulated variables influencing ventilation are oxygen, carbon dioxide, and pH.
- Atmospheric partial pressures: PO2 = 160 mm Hg, PCO2 = 0.25 mm Hg.
- Alveolar partial pressures: PO2 = 100 mm Hg, PCO2 = 40 mm Hg.
- Arterial blood partial pressures: PO2 = 100 mm Hg, PCO2 = 40 mm Hg.
- Resting cell partial pressures: PO2 = 40 mm Hg, PCO2 = 46 mm Hg.
- Venous blood partial pressures: PO2 = 40 mm Hg, PCO2 = 46 mm Hg.
Factors Influencing Gas Exchange
- Factors influencing gas exchange between atmosphere and arterial blood include diffusion rate, surface area, concentration gradient, barrier permeability, and diffusion distance.
- These factors are negatively affected by pathological changes.
Gas Solubility and Partial Pressure
- Gas solubility impacts diffusion.
- Equilibrium is based on partial pressure, not concentration.
- Oxygen is not very soluble in water compared to air, leading to a higher concentration gradient requirement for oxygen than carbon dioxide.
- Carbon dioxide is more soluble in water than oxygen.
Oxygen Transport by Hemoglobin
- Hemoglobin (in red blood cells) carries 98% of oxygen.
- High PO2 promotes Hb +O2 → HbO2(oxyhemoglobin)
- Low PO2 promotes Hb + O2 ← HbO2
- Free oxygen is used in cellular respiration.
- Partial pressure of oxygen in plasma directly influences how much oxygen binds to hemoglobin.
CO2 Transport in Blood
- CO2 is converted to bicarbonate (HCO3-) aided by carbonic anhydrase.
- This reaction is essential for transporting CO2 and maintaining blood acidity.
- Venous blood carries CO2 dissolved in plasma (7%), as carbaminohemoglobin (23%), and as bicarbonate (70%).
Regulation of Ventilation
- Central and peripheral chemoreceptors monitor blood gases and pH.
- Control networks in the brain stem regulate somatic motor neurons to the respiratory muscles.
- Ventilation is modulated by chemoreceptors and mechanoreceptors and higher brain centers.
Mechanisms of Central and Peripheral Chemoreceptors
- Peripheral chemoreceptors, located in carotid bodies, are most sensitive to oxygen changes.
- They are activated when oxygen levels drop below 60 mm Hg, triggering a response to increase ventilation.
- Central chemoreceptors, located in the brainstem, monitor carbon dioxide and hydrogen ions in cerebrospinal fluid.
- Elevated carbon dioxide levels lead to increased hydrogen ions, which stimulate central chemoreceptors and heighten ventilation.
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Description
This quiz focuses on the principles of gas exchange in the lungs and tissues, detailing the impact of oxygen, carbon dioxide, and pH on ventilation. It also covers factors influencing diffusion rates and gas solubility concerning partial pressures. Test your understanding of these critical physiological concepts.
