Bicarbonate buffer system

The bicarbonate buffer system is an acid-base homeostatic mechanism involving the balance of carbonic acid (H₂CO₃), bicarbonate ion (HCO⁻
₃), and carbon dioxide (CO₂) in order to maintain pH in the blood and duodenum, among other tissues, to support proper metabolic function.^[1] Catalyzed by carbonic anhydrase, carbon dioxide (CO₂) reacts with water (H₂O) to form carbonic acid (H₂CO₃), which in turn rapidly dissociates to form a bicarbonate ion (HCO⁻
₃ ) and a hydrogen ion (H⁺) as shown in the following reaction:^[2]^[3]^[4]

{\rm {CO_{2}+H_{2}O\rightleftarrows H_{2}CO_{3}\rightleftarrows HCO_{3}^{-}+H^{+}}}

As with any buffer system, the pH is balanced by the presence of both a weak acid (for example, H₂CO₃) and its conjugate base (for example, HCO⁻
₃) so that any excess acid or base introduced to the system is neutralized.

Failure of this system to function properly results in acid-base imbalance, such as acidemia (pH < 7.35) and alkalemia (pH > 7.45) in the blood.^[5]

^ Krieg, Brian J.; Taghavi, Seyed Mohammad; Amidon, Gordon L.; Amidon, Gregory E. (2014-11-01). "In Vivo Predictive Dissolution: Transport Analysis of the CO2, Bicarbonate In Vivo Buffer System" (PDF). Journal of Pharmaceutical Sciences. 103 (11): 3473–3490. doi:10.1002/jps.24108. hdl:2027.42/109280. ISSN 1520-6017. PMID 25212721.
^ Oxtoby, David W.; Gillis, Pat (2015). "Acid-base equilibria". Principles of Modern Chemistry (8 ed.). Boston, MA: Cengage Learning. pp. 611–753. ISBN 978-1305079113.
^ Widmaier, Eric; Raff, Hershel; Strang, Kevin (2014). "The kidneys and regulation of water and inorganic ions". Vander's Human Physiology (13 ed.). New York, NY: McGraw-Hill. pp. 446–489. ISBN 978-0073378305.
^ Meldrum, N. U.; Roughton, F. J. W. (1933-12-05). "Carbonic anhydrase. Its preparation and properties". The Journal of Physiology. 80 (2): 113–142. doi:10.1113/jphysiol.1933.sp003077. ISSN 0022-3751. PMC 1394121. PMID 16994489.
^ Rhoades, Rodney A.; Bell, David R. (2012). Medical physiology : principles for clinical medicine (4th ed., International ed.). Philadelphia, Pa.: Lippincott Williams & Wilkins. ISBN 9781451110395.

[:0-1] Krieg, Brian J.; Taghavi, Seyed Mohammad; Amidon, Gordon L.; Amidon, Gregory E. (2014-11-01). "In Vivo Predictive Dissolution: Transport Analysis of the CO2, Bicarbonate In Vivo Buffer System" (PDF). Journal of Pharmaceutical Sciences. 103 (11): 3473–3490. doi:10.1002/jps.24108. hdl:2027.42/109280. ISSN 1520-6017. PMID 25212721.

[Oxtoby_2015-2] Oxtoby, David W.; Gillis, Pat (2015). "Acid-base equilibria". Principles of Modern Chemistry (8 ed.). Boston, MA: Cengage Learning. pp. 611–753. ISBN 978-1305079113.

[Widmaier_2013-3] Widmaier, Eric; Raff, Hershel; Strang, Kevin (2014). "The kidneys and regulation of water and inorganic ions". Vander's Human Physiology (13 ed.). New York, NY: McGraw-Hill. pp. 446–489. ISBN 978-0073378305.

[4] Meldrum, N. U.; Roughton, F. J. W. (1933-12-05). "Carbonic anhydrase. Its preparation and properties". The Journal of Physiology. 80 (2): 113–142. doi:10.1113/jphysiol.1933.sp003077. ISSN 0022-3751. PMC 1394121. PMID 16994489.

[5] Rhoades, Rodney A.; Bell, David R. (2012). Medical physiology : principles for clinical medicine (4th ed., International ed.). Philadelphia, Pa.: Lippincott Williams & Wilkins. ISBN 9781451110395.

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