The human body employs intricate mechanisms to counteract changes in blood pH, preventing conditions like acidosis (pH < 7.35) and alkalosis (pH > 7.45). These compensatory responses aim to restore normal arterial blood pH by engaging respiratory or renal systems, depending on the source of the imbalance.

Respiratory Compensation
This mechanism addresses metabolic-induced pH imbalances by adjusting breathing rates. Respiratory compensation begins within minutes of detecting a pH disturbance and reaches peak efficacy within hours.

  1. In metabolic acidosis (low blood pH), hyperventilation occurs, increasing the rate of carbon dioxide (CO2) exhalation. Reduced CO2levels decrease the formation of carbonic acid (H2CO3), leading to fewer hydrogen ions (H⁺) and raising blood pH toward normal.
  2. In metabolic alkalosis (high blood pH), the body responds with hypoventilation—slower, shallower breathing. This allows CO2to accumulate in the blood, increasing carbonic acid formation and H⁺ release and lowering pH toward normal levels.

Renal Compensation
The kidneys take over with renal compensation when the pH imbalance originates from respiratory causes. This process involves the kidneys modulating the secretion and reabsorption of H⁺ and bicarbonate ions (HCO3⁻) in the tubules. Although renal responses begin within minutes, they take several days to reach maximum effectiveness.

  1. In respiratory acidosis (low pH due to excess CO2), the kidneys retain bicarbonate ions, which buffer excess H⁺ and help form carbonic acid.
  2. In respiratory alkalosis (high pH due to low CO2), the kidneys excrete bicarbonate ions while reducing H⁺ secretion. This decreases blood bicarbonate levels, promotes carbonic acid dissociation, releases more H+, and lowers pH.

These compensatory mechanisms highlight the body’s ability to dynamically regulate blood pH, ensuring stability for critical physiological processes. While respiratory compensation is faster, renal compensation provides a more robust and long-term solution to acid-base imbalances.

From Chapter 30:

article

Now Playing

30.19 : Compensation Mechanisms

Fluid, Electrolyte, and Acid-Base Balance

39 Views

article

30.1 : Body Water Content and Fluid Compartments

Fluid, Electrolyte, and Acid-Base Balance

220 Views

article

30.2 : Composition of Body Fluids

Fluid, Electrolyte, and Acid-Base Balance

160 Views

article

30.3 : Fluid Movement Between Compartments

Fluid, Electrolyte, and Acid-Base Balance

185 Views

article

30.4 : Regulation of Water Intake

Fluid, Electrolyte, and Acid-Base Balance

170 Views

article

30.5 : Regulation of Water Output

Fluid, Electrolyte, and Acid-Base Balance

124 Views

article

30.6 : Disorder of Water Balance

Fluid, Electrolyte, and Acid-Base Balance

138 Views

article

30.7 : Roles of Electrolytes: Sodium and Potassium

Fluid, Electrolyte, and Acid-Base Balance

63 Views

article

30.8 : Roles of Electrolytes: Chloride and Bicarbonate

Fluid, Electrolyte, and Acid-Base Balance

41 Views

article

30.9 : Roles of Electrolytes: Calcium and Phosphate

Fluid, Electrolyte, and Acid-Base Balance

49 Views

article

30.10 : Regulation of Sodium and Potassium

Fluid, Electrolyte, and Acid-Base Balance

56 Views

article

30.11 : Acid-Base Balance

Fluid, Electrolyte, and Acid-Base Balance

123 Views

article

30.12 : Buffer Systems in the Body

Fluid, Electrolyte, and Acid-Base Balance

179 Views

article

30.13 : Protein Buffers in Blood Plasma and Cells

Fluid, Electrolyte, and Acid-Base Balance

175 Views

article

30.14 : Phosphate Buffer

Fluid, Electrolyte, and Acid-Base Balance

193 Views

See More

JoVE Logo

Privacy

Terms of Use

Policies

Research

Education

ABOUT JoVE

Copyright © 2025 MyJoVE Corporation. All rights reserved