Buffer Chemistry and Blood pH Homeostasis

Vocabulary flashcards covering the chemical foundations of buffer solutions, blood pH regulation, physiological buffer systems, and the molecular mechanisms of acidosis and alkalosis.

Buffer (Chemical Definition)

A solution formed by combining a weak acid and its conjugate base that resists large changes in pH when small amounts of an acid or a base are added.

Brønsted-Lowry Acid

A chemical species defined as a proton donor, such as carbonic acid ($H_2CO_3$).

Brønsted-Lowry Base

A chemical species defined as a proton acceptor, such as the bicarbonate ion ($HCO_3^-$) or hydroxide ion ($OH^-$).

Buffer Neutralization of Acid

The reaction in which an added hydronium ion ($H_3O^+$) donates a proton to a bicarbonate ion ($HCO_3^-$), converting them into carbonic acid and water: $H_3O^+ + HCO_3^- \rightarrow H_2CO_3 + H_2O$.

Buffer Neutralization of Base

The reaction in which an added hydroxide ion ($OH^-$) accepts a proton from carbonic acid ($H_2CO_3$), converting them into a bicarbonate ion and water: $OH^- + H_2CO_3 \rightarrow HCO_3^- + H_2O$.

Normal Physiological Blood pH Range

The strictly regulated range between $7.35$ and $7.45$ required to maintain vital biochemical reactions and enzyme function in the human body.

Acidosis

A potentially fatal clinical condition in which blood pH falls below the normal threshold of $7.35$.

Alkalosis

A potentially fatal clinical condition characterized by abnormally high basicity, occurring when blood pH rises above the normal threshold of $7.45$.

Salt Bridge

An ionic bond formed between a positively charged cation and a negatively charged anion on amino acid side chains that stabilizes a protein's three-dimensional shape near a neutral pH of approximately $7$.

Protein Denaturation

The structural collapse of a protein's compact three-dimensional shape resulting from the disruption of stabilizing bonds (such as salt bridges), causing enzymes to lose catalytic ability.

Alkalosis-Induced Ammonium Deprotonation

The molecular reaction occurring during alkalosis where excess hydroxide ions react with positively charged ammonium groups, eliminating salt bridges: $-NH_3^+ + OH^- \rightarrow -NH_2 + H_2O$.

Carbonic Acid-Bicarbonate Buffer System

The primary and most critical buffer system in blood serum, formed by carbonic acid ($H_2CO_3$) and the bicarbonate ion ($HCO_3^-$).

Carbonic Acid Formation Reaction

The addition reaction occurring in blood serum where dissolved cellular carbon dioxide reacts with water to yield carbonic acid: $CO_2 + H_2O \rightarrow H_2CO_3$.

Phosphate Buffer System

A secondary physiological buffer system composed of the weak acid dihydrogen phosphate ion ($H_2PO_4^-$) and its conjugate base, the hydrogen phosphate ion ($HPO_4^{2-}$).

Protein and Amino Acid Buffer System

A tertiary physiological buffer system composed of amino acids, proteins, and polypeptides whose functional groups alternate between acidic and conjugate base forms to resist pH changes.

Respiratory System pH Regulation

The organ-mediated process by which the lungs maintain blood pH by managing gaseous compounds, specifically controlling the concentration of $CO_2$ through respiratory exchange and ventilation.

Renal System pH Regulation

The organ-mediated process by which the kidneys maintain blood pH by filtering, excreting, and reabsorbing ionic species such as $HCO_3^-$, $H_3O^+$, $H_2PO_4^-$, and $HPO_4^{2-}$.