Author: Yuju (Julie) Hwang
The bicarbonate system plays a critical role in maintaining the body's acid-base balance, ensuring that the blood pH remains within a safe range. Through an interplay of carbon dioxide, bicarbonate ions, and carbonic acid, this buffering system effectively neutralizes excess hydrogen ions, preventing the blood from becoming too acidic or too alkaline. The proper functioning of the bicarbonate system is vital for overall health and preventing unlikely disorders to occur.
Almost every living organism cannot survive under extreme pH conditions. The optimal pH level for living organisms is between 6.5 and 8.5. For humans, the level is between 6.8 and 7.4, which is close to a neutral pH. While substances close to a neutral pH are safe, substances outside the optimal pH range or at extremes on either side could be inhospitable to the human body. For instance, when too much acid is produced inside the body, it may lead to severe acidosis, eventually leading to harsh body conditions like heart disease and coma. Despite such dangers from extremely high and low PH, people use soap that has a pH level close to 12 and drinks coffee or orange juice, which has a pH level lower than 5. Thus, it is questionable how living organisms regulate the pH level in their bodies to maintain homeostasis.
Among numerous buffers in the human body, including protein buffers or phosphate buffers, the Carbonic Acid-Bicarbonate buffer system, or bicarbonate buffer system, is the most important buffer for the metabolism and maintenance of pH homeostasis of blood. This process mainly involves three components: Carbonic acid (H2CO3), Bicarbonate ion (HCO3-), and Carbon dioxide (CO2).
There are broadly two cases that involve the buffer system: (1) when the blood pH is too acidic and (2) when the blood pH is too alkaline. In these cases, the pH level has to be regulated close to the neutral pH or optimal range of pH. Following is the equation of carbonic bicarbonate that regulates the pH:
H2O + CO2 H2CO3 H+ + HCO3-
When the blood is too acidic
In this case, high acidity may result in metabolic acidosis and cause accelerated heartbeat, or tachycardia, or fatigue. The major reason is due to an increase in hydrogen ions (H+). Then, the equilibrium will shift to the left. To prevent blood from becoming overly acidic, bicarbonate ions act as a buffer to neutralize since it forms carbonic acid with hydrogen ions. Excess carbonic acid can be converted to carbon dioxide gas which is being exhaled through the lungs. This prevents too many free hydrogen ions from building up in the blood.
When the blood is too alkalic
When the blood is too alkalic, which means the pH of the blood is more basic than what it should be. This metabolic alkalosis may cause low calcium levels which may result in lethargy or in severe cases, coma. Then, the equilibrium will shift to the right. When the bicarbonate decreases by forming carbonic acid, carbonic acid will break down and release carbon dioxide and water to maintain the pH range.
It’s critical for the bicarbonate buffer system to interplay for blood pH since maintaining pH in the correct range is crucial to prevent disorders in the human body.
Reference:
Carbon Dioxide Transport. (2013, December). Wikimedia Commons. https://commons.wikimedia.org/wiki/File:2325_Carbon_Dioxide_Transport.jpg
Haen Whitmer, K.M. (2021). A Mixed Course-Based Research Approach to Human Physiology. Ames, IA: Iowa State University Digital Press.
Indicators: Acidification. (2023, June 15). US EPA. https://www.epa.gov/national-aquatic-resource-surveys/indicators-acidification
Lewis, J. L., III. (2023, July 18). Acidosis. MSD Manual Consumer Version. https://www.msdmanuals.com/en-kr/home/hormonal-and-metabolic-disorders/acid-base-balance/acidosis
Metabolic acidosis. (n.d.). Cleveland Clinic.
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