Advanced Topic 544 of 1102 Acids, Bases & Electrochemistry
Blood Buffer System
Carbonic acid and bicarbonate keep blood pH near 7.4.
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In-depth explanation of Blood Buffer System
Blood is buffered mainly by the carbonic acid and bicarbonate system, in which dissolved carbon dioxide combines with water to form carbonic acid, which dissociates into hydrogen ions and bicarbonate ions. The balance is CO2 + H2O <-> H2CO3 <-> H+ + HCO3-, and it keeps arterial blood pH in the narrow range of 7.35 to 7.45. The lungs control carbon dioxide by breathing, while the kidneys adjust bicarbonate over longer periods. Deviations from this range cause acidosis or alkalosis, which are medically serious conditions. Understanding this buffer explains why breathing rate affects blood chemistry.
Going deeper: Blood Buffer System
Key ideas: Blood pH is held at 7.35 to 7.45 mainly by the carbonic acid and bicarbonate pair: CO2 + H2O gives H2CO3 gives H+ + HCO3-. Normal [HCO3-]/[CO2] is about 20 to 1, which with an apparent pKa of 6.1 gives pH 7.4. Lungs regulate CO2 within minutes; kidneys regulate bicarbonate over hours to days. Phosphate and proteins add buffering.
Common mistakes and connections: Students wonder how a 20:1 ratio buffers when pKa is far from 7.4: the system is open, because breathing removes CO2, so it is not a closed buffer. Acidosis is pH under 7.35, alkalosis above 7.45. Links to Le Chatelier, gas solubility and Henderson-Hasselbalch in physiology.
Visualization of Blood Buffer System
In blood the CO2/HCO3- buffer works near pKa 6.1; at pH 7.4 bicarbonate outnumbers dissolved CO2 about 20 to 1, with the lungs and kidneys adjusting each. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Hyperventilation removes CO2 from the blood, shifting the equilibrium to lower H+ and raising the blood pH, which can lead to alkalosis.
Frequently asked questions about Blood Buffer System
What is Blood Buffer System?
Carbonic acid and bicarbonate keep blood pH near 7.4.
Is Blood Buffer System a beginner, intermediate or advanced topic?
Blood Buffer System is a advanced topic in Acids, Bases & Electrochemistry. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Blood Buffer System?
Study these earlier topics in Acids, Bases & Electrochemistry first: Buffer Solutions, Henderson-Hasselbalch Equation, Buffer Capacity.
What comes after Blood Buffer System?
The next topics in Acids, Bases & Electrochemistry are Oxidation Number and Oxidation.
Can I practise Blood Buffer System with quizzes?
Yes. The interactive lesson includes a self-check question on Blood Buffer System, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Blood Buffer System fits in Acids, Bases & Electrochemistry
Blood Buffer System is topic 34 of 105 in Acids, Bases & Electrochemistry.