Comprehensive Guide to Acid-Base Balance and Blood Gas Analysis in Human Physiology

What is an acid?

A substance that releases H+ when dissolved in water/body fluids.

What is a base?

A substance that accepts or binds H+, lowering the amount of free H+.

What is acidosis?

The process by which protons are produced in large amounts, leading to increased H+.

What is acidemia?

A condition where blood pH is less than 7.35.

What is alkalosis?

The process by which there is a decrease in proton production/concentration (H+).

What is alkalemia?

A condition where blood pH is greater than 7.45.

What is a buffer?

A substance that can react as either an acid or a base, depending on the pH of the solution.

What is the normal pH range of blood?

7.35 to 7.45.

What do arterial blood gases (ABGs) provide information about?

Oxygenation and acid-base imbalance.

What are the three major determinants of oxygenation status?

PaO2, SaO2, and Hemoglobin.

How do the lungs control acid-base balance?

By regulating CO2 and therefore H2CO3 quickly through ventilation.

What role do chemoreceptors play in respiration control?

They respond to changes in the chemical composition of the fluid around them (pH and PaCO2).

What is the role of the kidneys in acid-base balance?

They regulate HCO3- levels in extracellular fluid and can excrete or conserve H+ ions.

What is the normal range for HCO3- in the blood?

22-26 mEq/L.

What indicates respiratory acidosis?

Increased CO2 levels (>45 mm Hg) and decreased pH (<7.35).

What indicates metabolic alkalosis?

Increased HCO3- levels (>28 mEq/L) and increased pH (>7.45).

What is a fully compensated state in acid-base balance?

When pH returns to normal range while CO2 and HCO3- are abnormal.

What is an uncompensated state in acid-base balance?

When pH is abnormal and neither CO2 nor HCO3- is compensating.

What is a partially compensated state in acid-base balance?

When pH is abnormal but one of the compensatory mechanisms is active.

What is the significance of the Allen's test?

It assesses the adequacy of collateral circulation before an ABG draw.

What does a low PaO2 indicate?

Hypoxemia.

What does a high PaCO2 indicate?

Hypercapnia, which can lead to respiratory acidosis.

What is the primary step in analyzing ABG results?

Analyze the pH to determine acidosis or alkalosis.