Anatomy Question: During normal respiration carbonic acid (H2CO3) and bicarbonat
ID: 3477705 • Letter: A
Question
Anatomy Question:
During normal respiration carbonic acid (H2CO3) and bicarbonate (HCO3-) help to regulate the amount of H+ ions in the blood. CO2 in the blood is readily converted to carbonic acid and most CO2 waste from skeletal muscles travels to the lungs as carbonic acid. If the concentration of H+ ions becomes too low carbonic acid is quickly converted to bicarbonate and free H+ ions; if the concentration of H+ ions becomes too high the reaction reverses. What is this an example of and what is its importance in regards to pH level?
Explanation / Answer
The example is of the Bicarbonate buffering system that exists in blood. When weak acid carbonic acid (H2CO3) equilibrates with bicarbonate (HCO3-) in solution, a bicarbonate buffer is formed.
H2CO3 + H2O H3O+ + HCO3-
In normal physiological system, the blood has more bicarbonate than carbonic acid. This high bicarbonate content in blood is necessary to neutralize the high amount of metabolic acid produce during metabolism. Conversely, carbonic acid is lower in blood due to low production of metabolic bases.
Carbonic acid breaks down to carbon dioxide and water readily in blood. Carbon dioxide is removed by the efficient respiratory system.
CO2 (g) + H2O (l) H2CO3 (aq) HCO3–(aq) + H +(aq)
The pH of blood is shown by the following equation:
pH= pKa- [CO2]/[HCO3-]
pKa remains constant.
Hence, pH of blood depends on concentration of Carbon dioxide: bicarbonate.
When pH of blood increases due to CO2 exhalation by lungs, H+ ions will decrease. Hence, H2CO3 will dissociate to form more H+ ions in blood, raising the pH to 7.
When the pH of blood decreases, H+ ions react with bicarbonate ions to form hydrogen carbonate (H2CO3). Formation of hydrogen carbonate will decrease the level of H+ ions, bringing the pH back to 7.