Acid-Base Balance and Compensation

Vocabulary flashcards covering the fundamentals of blood pH, the logarithmic scale, primary respiratory and metabolic acid-base disorders, their clinical causes, and renal and respiratory compensation mechanisms.

Normal Blood pH

The physiological range of blood pH in the human body, maintained between $7.35$ and $7.45$.

Logarithmic pH Scale

A mathematical scale where each step represents a power of $10$, meaning a pH of $3$ possesses $100{,}000$ ($10^5$) times more hydrogen ions ($H^+$) than a pH of $8$.

Carbonic Acid Reaction

The reversible chemical process $CO_2 + H_2O \rightarrow H_2CO_3 \rightarrow H^+ + HCO_3^-$, through which retained carbon dioxide forms carbonic acid that dissociates into free protons and bicarbonate, lowering pH.

Respiratory Acidosis

An acid-base disturbance caused by hypoventilation and failure of the lungs to blow off sufficient carbon dioxide, leading to accumulated $CO_2$, increased protons, and a blood pH below $7.35$.

Respiratory Alkalosis

An acid-base disturbance caused by hyperventilation and blowing off too much carbon dioxide ($CO_2$), which results in a rise in blood pH above $7.45$.

Metabolic Acidosis

An acid-base disturbance resulting from the overproduction of acid, excessive loss of bicarbonate, or failure of the kidneys to excrete acid, driving blood pH below $7.35$.

Metabolic Alkalosis

An acid-base disturbance resulting from a loss of acid or an accumulation of bicarbonate, driving blood pH above $7.45$.

Arterial Blood Gas (ABG)

A clinical diagnostic evaluation measuring parameters such as pH, partial pressure of carbon dioxide ($CO_2$), and bicarbonate to identify acid-base disturbances.

Surfactant

A critical substance in the respiratory system not made by extremely premature infants; medical facilities often struggle to support infants under $24$ to $26$ weeks of gestation because they lack it, whereas infants reaching at least $36$ weeks are more capable of producing it.

Hypokalemia

Abnormally low potassium concentration in the blood, noted as a potential cause of metabolic alkalosis.

Aldosterone

A hormone that triggers sodium and water retention in the kidneys while promoting potassium excretion; an excess can lead to potassium depletion and metabolic alkalosis.

Compensation

A homeostatic response where one organ system (respiratory or renal) alters its function to correct an acid-base imbalance created by the opposite system, restoring blood pH toward normal without fixing the underlying problem.

Respiratory Compensation

A fast-acting compensatory mechanism operating within minutes to hours that changes ventilation depth and rate to regulate carbon dioxide levels in response to metabolic disturbances.

Renal Compensation

A slower-acting compensatory mechanism taking hours to days where the kidneys adjust the excretion of hydrogen ions ($H^+$) and the reabsorption of bicarbonate ($HCO_3^-$) to balance respiratory disturbances.

Uncompensated Respiratory Acidosis

A clinical state characterized by a low blood pH ($< 7.35$), abnormally high carbon dioxide ($CO_2$), and normal bicarbonate ($HCO_3^-$) levels.

Compensated Respiratory Acidosis

A clinical state where blood pH is restored to the normal range ($7.35$ to $7.45$) through renal retention of bicarbonate ($HCO_3^-$), presenting with elevated $CO_2$ alongside elevated bicarbonate.

Uncompensated Metabolic Acidosis

A clinical state characterized by a low blood pH ($< 7.35$), abnormally low bicarbonate ($HCO_3^-$), and normal carbon dioxide ($CO_2$) levels.

Uncompensated Respiratory Alkalosis

A clinical state characterized by an elevated blood pH ($> 7.45$), abnormally low carbon dioxide ($CO_2$), and normal bicarbonate ($HCO_3^-$) levels.

Uncompensated Metabolic Alkalosis

A clinical state characterized by an elevated blood pH ($> 7.45$), abnormally high bicarbonate ($HCO_3^-$), and normal carbon dioxide ($CO_2$) levels.