Acid-Base Balance Health Article

Definition

Acid-base balance can be defined as homeostasis of the body fluids at a normal arterial blood pH ranging between 7.37 and 7.43.

Description

An acid is a substance that acts as a proton donor. In contrast, a base, also known as an alkali, is frequently defined as a substance that combines with a proton to form a chemical bond. Acid solutions have a sour taste and produce a burning sensation with skin contact. A base is any chemical compound that produces hydroxide ions when dissolved in water. Base solutions have a bitter taste and a slippery feel. Despite variations in metabolism, diet, and environmental factors, the body's acid-base balance, fluid volume, and electrolyte concentration are maintained within a narrow range.

Function

Many naturally occurring acids are necessary for life. For example, hydrochloric acid is secreted by the stomach to assist with digestion. The chemical composition of food in the diet can have an effect on the body's acid-base production. Components that affect acid-base balance include protein, chloride, phosphorus, sodium, potassium, calcium, and magnesium. In addition, the rate at which nutrients are absorbed in the intestine will alter acid-base balance.

Cells and body fluids contain acid-base buffers, which help prevent rapid changes in body fluid pH over short periods of time, until the kidneys pulmonary systems can make appropriate adjustments. The kidneys and pulmonary system then work to maintain acid-base balance through excretion in the urine or respiration. The partial pressure of carbon dioxide gas (PCO₂) in the pulmonary system can be measured with a blood sample and correlates with blood carbon dioxide (CO₂) levels. PCO₂ can then be used as an indicator of the concentration of acid in the body. The concentration of base in the body can be determined by measuring plasma bicarbonate (HCO_3-) concentration. When the acid-base balance is disturbed, the respiratory system can alter PCO₂ quickly, thus changing the blood pH and correcting imbalances. Excess acid or base is then excreted in the urine by the renal system to control plasma bicarbonate concentration. Changes in respiration occur primarily in minutes to hours, while renal function works to alter blood pH within several days.