Acid–base balance

Acid–base balance refers to the homeostatic regulation of the pH levels of bodily fluids, primarily the blood. This balance is crucial for maintaining optimal functioning of the body's cells and organs. The human body requires a tightly controlled pH level in the blood, typically around 7.4, to function efficiently. Deviations from this range can lead to serious health issues, including Acidosis and Alkalosis, which are conditions of excessive acidity and alkalinity, respectively.

Mechanisms of Regulation

The body maintains acid-base balance through three primary mechanisms: respiratory, renal, and buffer systems.

Respiratory System

The respiratory system regulates blood pH by controlling the levels of carbon dioxide (CO2) in the blood. CO2 is a by-product of metabolism and is slightly acidic. Through the process of ventilation, CO2 is expelled from the body, which can help to raise the pH of the blood if it becomes too acidic.

Renal System

The renal system contributes by excreting acids and reabsorbing bicarbonate from the urine. This process is slower than respiratory compensation but is more effective in maintaining long-term pH balance. The kidneys regulate the concentration of bicarbonate (HCO3−), a base, in the blood, adjusting the rate of excretion or reabsorption as needed.

Buffer Systems

Buffer systems in the blood and other bodily fluids instantly neutralize excess acids or bases. The most important of these is the bicarbonate buffer system, which balances the concentration of bicarbonate and carbonic acid in the blood.

Acid-Base Disorders

Disruptions in the acid-base balance can lead to disorders such as Acidosis and Alkalosis. Acidosis is characterized by an excess of acid or a loss of base in the body, leading to a decrease in blood pH. Alkalosis, conversely, occurs when there is an excess of base or a loss of acid, resulting in an increase in blood pH.

Types of Acidosis

• Metabolic Acidosis: Caused by an increase in acid production or a decrease in bicarbonate.
• Respiratory Acidosis: Results from an accumulation of CO2 due to reduced lung function or hypoventilation.

Types of Alkalosis

• Metabolic Alkalosis: Occurs due to an excess of bicarbonate or a loss of acid from the body.
• Respiratory Alkalosis: Caused by excessive loss of CO2 through hyperventilation.

Diagnosis and Treatment

Diagnosis of acid-base disorders typically involves measuring the pH, CO2, and bicarbonate levels in the blood through an Arterial blood gas test. Treatment depends on the underlying cause and may involve measures to correct the pH balance, such as administering bicarbonate for acidosis or controlling breathing in the case of respiratory alkalosis.