WEEK 1-6 Biochemistry Lab: pH Measurement and Buffer Systems - Vocabulary

Vocabulary flashcards covering key terms from pH measurement, buffers, acid-base theory, and body pH regulation as presented in the lecture notes.

Buffer

An aqueous solution that minimizes pH fluctuations by containing a weak acid and conjugate base (or vice versa); used to maintain stable pH for chemical processes and medicines.

pH

A scale (0-14) that measures how acidic or basic a solution is, based on hydrogen ion concentration.

pH Meter

A scientific instrument used to measure the acidity or basicity of a solution, typically with an electrode and Automatic Temperature Compensation (ATC).

Henderson-Hasselbalch equation

A equation used to estimate buffer pH: pH = pKa + log([conjugate base]/[acid]).

Calibration

The process of setting a pH meter using known standard solutions (e.g., pH 4.00, 6.86, 9.18) to ensure accurate readings.

ATC (Automatic Temperature Compensation)

A feature that automatically compensates pH readings for temperature changes to improve accuracy.

Buffer solutions

Solutions containing a weak acid and its conjugate base (or vice versa) used to maintain a stable pH during experiments.

Conjugate base

The species formed when an acid donates a proton; part of a buffer pair (acid/conjugate base).

Conjugate acid

The species formed when a base accepts a proton; part of a buffer pair.

Arrhenius acid

A substance that increases the concentration of H+ ions in water.

Arrhenius base

A substance that increases the concentration of OH- ions in water.

Bronsted-Lowry acid

A substance that donates a proton (H+).

Bronsted-Lowry base

A substance that accepts a proton (H+).

Lewis acid

A substance that accepts an electron pair.

Lewis base

A substance that donates an electron pair.

Amphoteric (water)

Water can act as both an acid and a base, forming conjugate acid-base pairs.

pKa

The negative logarithm of Ka; a measure of acid strength and a key value in buffer calculations.

Ka

The acid dissociation constant; a measure of acid strength.

Buffer capacity

The ability of a buffer to resist changes in pH under added acid or base.

Bicarbonate buffer system

The body's main buffer system, involving HCO3-, H2CO3, CO2, and H2O to regulate blood pH.

Carbonic acid

H2CO3, the weak acid in the bicarbonate buffer that equilibrates with CO2 and H2O.

Carbon dioxide

CO2; dissolves in water to form carbonic acid in the bicarbonate buffer system.

Bicarbonate ion

HCO3-, the conjugate base of carbonic acid in the bicarbonate buffer system.

CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-

The reversible reactions forming and consuming carbonic acid and bicarbonate in buffering.

Respiratory compensation

Rapid pH adjustment via changes in CO2 elimination by the lungs.

Renal compensation

Long-term pH adjustment through H+ excretion and HCO3- reabsorption in the kidneys.

Intracellular pH

pH inside cells, buffered by systems such as H2PO4-/H3PO4.

Blood pH range

Normal blood pH: 7.35–7.45.

Acidosis

Condition of decreased blood pH (more acidic).

Alkalosis

Condition of increased blood pH (more basic).

ABG (Arterial Blood Gas)

A test measuring pH, PaCO2, PaO2, and HCO3- to diagnose acid-base disorders.

Protein buffer system

Buffering using proteins as weak acids in body fluids.

Phosphate buffer system

Buffer system important in urine and intracellular fluid, involving H2PO4-/H3PO4.

Hemoglobin buffer system

Buffering in red blood cells using hemoglobin to modulate pH.

Good's buffers

Zwitterionic buffers with both positive and negative charges to minimize biological interference.

Acetic acid/acetate buffer

Buffer pair CH3COOH and CH3COO-, commonly used in biochemical studies.

Formic acid/formate buffer

Buffer pair HCOOH and HCOO-, with antibacterial properties.

Pyridine/pyridinium buffer

Buffer pair C5H5N and C5H5NH+, used in industrial applications.

Ammonia/ammonium buffer

Buffer pair NH3 and NH4+, used to calibrate pH meters and stabilize dosage forms.

Gastric fluid pH

Highly acidic pH range of roughly 1.5–3.5.

Urine pH

pH range that varies widely from about 4.5 to 8.0.

Intracellular pH (range)

Approximately 7.0–7.4 inside cells.

Diabetic ketoacidosis

A metabolic state of excessive ketone production leading to metabolic acidosis.

Chronic obstructive pulmonary disease (COPD)

A respiratory disease that can cause respiratory acidosis by impaired CO2 removal.

Metabolic acidosis

Acidosis due to increased acid production or decreased excretion; low HCO3-.

Metabolic alkalosis

Alkalosis due to increased base or decreased acid; high HCO3-.