Transport Of Gases Flashcards
(32 cards)
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What are the three forms of oxygen transport in blood?
- Dissolved in plasma (1-2%), 2. Bound to hemoglobin (98-99%), 3. As oxyhemoglobin (HbO₂).
What is the role of hemoglobin in oxygen transport?
Hemoglobin binds to oxygen in the lungs and releases it in tissues, facilitating oxygen delivery.
What is the O₂-hemoglobin dissociation curve?
A graph showing the relationship between oxygen saturation of hemoglobin (SaO₂) and partial pressure of oxygen (PaO₂).
What does the sigmoid shape of the O₂-hemoglobin dissociation curve indicate?
It indicates cooperative binding of oxygen to hemoglobin (binding of one O₂ molecule increases affinity for more O₂).
What is P50 in the O₂-hemoglobin dissociation curve?
The partial pressure of oxygen at which hemoglobin is 50% saturated; normal P50 is ~27 mmHg.
What factors shift the O₂-hemoglobin dissociation curve to the RIGHT?
- Increased CO₂ (Bohr effect), 2. Decreased pH (acidosis), 3. Increased temperature, 4. Increased 2,3-BPG.
What factors shift the O₂-hemoglobin dissociation curve to the LEFT?
- Decreased CO₂, 2. Increased pH (alkalosis), 3. Decreased temperature, 4. Decreased 2,3-BPG, 5. Fetal hemoglobin (HbF).
What is the physiological significance of a RIGHT shift in the O₂-hemoglobin dissociation curve?
It indicates decreased hemoglobin affinity for O₂, promoting O₂ release to tissues (e.g., during exercise or acidosis).
What is the physiological significance of a LEFT shift in the O₂-hemoglobin dissociation curve?
It indicates increased hemoglobin affinity for O₂, promoting O₂ binding in the lungs (e.g., in fetal circulation or alkalosis).
What is oxygen saturation (SaO₂)?
The percentage of hemoglobin binding sites occupied by oxygen; normal SaO₂ is 95-100%.
What is oxygen content (CaO₂)?
The total amount of oxygen carried in blood, calculated as (1.34 × Hb × SaO₂) + (0.003 × PaO₂).
What is oxygen extraction?
The amount of oxygen extracted by tissues from arterial blood, calculated as arterial O₂ content - venous O₂ content.
What are the three forms of CO₂ transport in blood?
- Dissolved in plasma (5-10%), 2. As bicarbonate (HCO₃⁻) (60-70%), 3. Bound to hemoglobin as carbaminohemoglobin (20-30%).
How is CO₂ converted to bicarbonate (HCO₃⁻) in RBCs?
CO₂ combines with water to form carbonic acid (H₂CO₃), which dissociates into H⁺ and HCO₃⁻ via carbonic anhydrase.
What is the chloride shift (Hamburger phenomenon)?
The exchange of HCO₃⁻ (out of RBCs) for Cl⁻ (into RBCs) to maintain electroneutrality during CO₂ transport.
What is the Bohr effect?
The phenomenon where increased CO₂ and decreased pH reduce hemoglobin’s affinity for O₂, promoting O₂ release to tissues.
What is the Haldane effect?
The phenomenon where deoxygenated hemoglobin has a higher affinity for CO₂ and H⁺, facilitating CO₂ transport from tissues to lungs.
What is the physiological significance of the Bohr effect?
It enhances O₂ delivery to tissues during high metabolic activity (e.g., exercise) by promoting O₂ release from hemoglobin.
What is the physiological significance of the Haldane effect?
It enhances CO₂ removal from tissues and transport to the lungs by increasing CO₂ binding to deoxygenated hemoglobin.
What is the CO₂ dissociation curve?
A graph showing the relationship between CO₂ content in blood and partial pressure of CO₂ (PCO₂).
How does the CO₂ dissociation curve differ from the O₂-hemoglobin dissociation curve?
The CO₂ dissociation curve is more linear, while the O₂-hemoglobin dissociation curve is sigmoidal.
What is the role of carbonic anhydrase in CO₂ transport?
It catalyzes the conversion of CO₂ and H₂O to H₂CO₃, which dissociates into H⁺ and HCO₃⁻, facilitating CO₂ transport as bicarbonate.
What is the effect of fetal hemoglobin (HbF) on the O₂-hemoglobin dissociation curve?
HbF has a higher affinity for O₂, causing a LEFT shift in the curve, which facilitates O₂ transfer from maternal to fetal blood.
