Final answer:
The transport of gases in the blood involves hemoglobin-based equilibria for oxygen and carbon dioxide. Oxygen binds with hemoglobin to form oxyhemoglobin, while carbon dioxide forms carbaminohemoglobin, with equilibrium shifts based on partial pressures. Additionally, bicarbonate is a major form of carbon dioxide transport in plasma.
Step-by-step explanation:
The transport of oxygen and carbon dioxide in the blood involves a series of equilibria, primarily mediated by hemoglobin within red blood cells. Oxygen from the lungs binds to hemoglobin, forming oxyhemoglobin (HbOx), while carbon dioxide from body tissues binds to hemoglobin to form carbaminohemoglobin (HbCO2).
The equilibrium reactions can be summarized as follows:
- Oxygen transport: O2 + Hb ↔ HbOx
- Carbon dioxide transport: CO2 + Hb ↔ HbCO2
- Hemoglobin buffering: CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+
In tissues, a higher partial pressure of carbon dioxide promotes the binding of CO2 to hemoglobin to form HbCO2. In the lungs, a higher partial pressure of oxygen promotes the release of CO2 from HbCO2 and the binding of O2 to form HbOx, facilitating the exchange of gases. Additionally, carbon dioxide can be transported as bicarbonate ions in plasma, formed by the action of carbonic anhydrase, which catalyzes the reaction of CO2 with water to form carbonic acid (H2CO3) that dissociates into bicarbonate (HCO3-) and hydrogen ions (H+).