2. Sistemas amortiguadores del organismo. Bioquímica.

Understanding Buffer Systems in Biochemistry

Introduction to Buffer Systems

• The concept of biochemical equilibrium is foundational for understanding the body's buffering systems, which help maintain pH levels within physiological limits.

• Physiological buffers present in the human body can capture and release hydrogen ions from both endogenous and exogenous sources.

Key Buffers in the Body

• Major buffering agents include bicarbonate, phosphate, hemoglobin, and proteins; these can be found in intracellular or extracellular environments.

• Hemoglobin is highlighted as the most abundant protein in erythrocytes, capable of capturing hydrogen ions produced during carbonic anhydrase reactions.

Mechanism of Intracellular Buffers

• When plasma hydrogen ion concentration increases, they enter cells in exchange for potassium ions, potentially leading to hyperkalemia.

• Conversely, a decrease in plasma hydrogen ions or an increase in bicarbonate results in intracellular buffers releasing hydrogen ions into plasma, which may cause hypokalemia.

Bicarbonate Buffer System

• The bicarbonate buffer system accounts for 75% of physiological pH regulation; it consists of two components: bicarbonate (the metabolic component) and carbon dioxide (the respiratory component).

• The ideal ratio between bicarbonate and carbon dioxide is 20:1 to maintain normal pH levels; any variation disrupts this balance affecting protein ionization.

Functionality of Bicarbonate Buffering

• The primary role of the bicarbonate buffer is to minimize pH changes. An increase in hydrogen ion concentration leads to a decrease in plasma pH.

• Under acidic conditions, bicarbonate neutralizes excess hydrogen ions forming carbonic acid that converts into carbon dioxide and water through a reaction catalyzed by carbonic anhydrase.

Restoration of Normal pH Levels

• When there’s a reduction in hydrogen ion concentration causing increased plasma pH, carbonic acid dissociates back into hydrogen ions and bicarbonate to restore balance.