Acid-Base and Buffers Physiology Flashcards

A complete set of practice questions covering acid-base definitions, the biological importance of pH, blood gas parameters, buffer mechanisms, and compensation patterns for clinical imbalances.

What is the definition of an acid and a base based on proton movement?

An acid is a substance that can donate hydrogen ions [proton] in solution, while a base is a substance that can accept hydrogen ions [proton].

List two examples of strong acids and two examples of weak acids provided in the text.

Strong acids: $HCl$, $H_2SO_4$, and $H_2PO_4$; Weak acids: $H_2CO_3$ and $CH_3COOH$.

List two examples of strong bases and two examples of weak bases provided in the text.

Strong bases: $NaOH$ and $KOH$; Weak bases: $NaHCO_3$, $NH_3$, and $CH_3COONa$.

How are volatile acids and fixed acids distinguished by their daily production amounts in the body?

Volatile acids equate to approximately $20,000\,mmol$ of $CO_2$, while fixed acids account for $40-80\,mmol$ of $H^+$.

What formula represents the hydration of carbon dioxide catalyzed by carbonic anhydrase?

$$CO_2 + H_2O \rightarrow H_2CO_3 \rightarrow H^+ + HCO_3^-$$

What is the normal range and average for $PaCO_2$ (Partial Pressure of Carbon Dioxide) in arterial blood?

Normal range: $36 \sim 44\,mmHg$; Average: $40\,mmHg$.

Define the numerical thresholds for respiratory acidosis and respiratory alkalosis based on $PaCO_2$.

Respiratory acidosis: $> 46\,mmHg$; Respiratory alkalosis: $< 33\,mmHg$.

What is the clinical definition of the pH scale and the Henderson-Hasselbalch derived formula for it?

pH is a measure of hydrogen ions $[H^+]$ in a solution, expressed as $pH = -\log([H^+])$.

What is the normal range for arterial blood pH, and what are the terms for deviations outside this range?

Normal range: $7.35 - 7.45$; Serum $pH > 7.45$ is alkalosis/alkalemia, and serum $pH < 7.35$ is acidosis/acidemia.

What are the three systems that maintain acid-base balance in the ECF, and what is their response time?

1) Chemical Buffers (Immediate response/less than a second), 2) Respiratory Regulation (Immediate response/seconds to minutes), and 3) Renal Regulation (Delayed response/minutes to hours or days).

Define a 'Buffer Solution' and its primary aim in human blood.

A buffer is a solution of a weak acid and its conjugate base that resists changes in pH; its aim is to maintain blood pH between $7.35$ and $7.45$.

What are the four examples of chemical buffers mentioned in the text, and which is the most important?

Bicarbonate buffer, Intracellular protein buffers (including hemoglobin), Phosphate buffers, and Ammonium buffer. Bicarbonate is the most important.

What is the predominant buffer in the ECF and what is its specific ratio?

Bicarbonate buffer system, with a $HCO_3^- : H_2CO_3$ ratio of $20:1$.

What is the principal buffer in the Intracellular Fluid (ICF), and what is its $pKa$?

The Phosphate buffer system ($H_2PO_4^- \rightleftharpoons HPO_4^{2-} + H^+$), with a $pKa$ of $6.8$.

What are three industrial or laboratory applications of buffers?

Chemicals manufacturing, calibration of pH meters, and preparation of biological samples for research (e.g., PBS at $pH\,7.4$).

What is Kussmaul breathing and what does it indicate?

An increase in rate and depth of ventilation indicating an attempt by the lungs to blow off excess acid ($CO_2$) to keep pH under control.

List the four mechanisms by which the kidneys provide effective regulation of acid load.

1) Excretion of $H^+$, 2) Reabsorption of $HCO_3^-$, 3) Excretion of acids by phosphate buffer, and 4) Excretion of $NH_3$ largely as $NH_4^+$.

Define 'Uncompensated' acid-base imbalance.

Either $PaCO_2$ or $HCO_3^-$ is abnormal while all other parameters are normal.

Define 'Partially compensated' acid-base imbalance.

Compensatory mechanisms are active but the pH is not yet normalized; both $PaCO_2$ and $HCO_3^-$ are abnormal in the same direction.

Define 'Fully compensated' acid-base imbalance.

Compensatory mechanisms have normalized the blood pH, though both $PaCO_2$ and $HCO_3^-$ remain abnormal in the same direction.

In Metabolic Acidosis, what is the primary disturbance and the corresponding compensation?

Primary disturbance: decrease in $HCO_3^-$; Compensation: Lungs increase the removal of $CO_2$ (resulting in a compensatory decrease in $PCO_2$).