Acid-Base and Electrolyte Balance — MCQs

Q: Most important buffer system in human blood:

Bicarbonates. ***Bicarbonates*** - The **bicarbonate buffer system** is the most significant extracellular buffer in human blood due to its high concentration and the ability of its components (CO2 and HCO3-) to be regulated by the lungs and kidneys, respectively. - It rapidly equilibrates with dissolved CO2, making it highly effective at buffering both acid and base imbalances to maintain **blood pH**. *Hemoglobin* - **Hemoglobin** is an important intracellular buffer within red blood cells, primarily buffering carbonic acid formed from CO2 transport. - While powerful within the red blood cell, it is not the primary buffer system in the overall plasma (extracellular fluid). *Chloride ions* - **Chloride ions** are crucial for maintaining electroneutrality in red blood cell buffering processes (e.g., the **chloride shift**), but they do not directly act as a buffer in the traditional sense of accepting or donating protons. - Their primary role in pH balance is indirect, supporting the function of other buffer systems. *Phosphate buffer system* - The **phosphate buffer system** is important, particularly in intracellular fluid and renal tubules, due to its pKa being close to physiological pH. - However, its concentration in the extracellular fluid (blood plasma) is relatively low compared to bicarbonate, making it less significant for overall blood buffering.

Q: Maximum storage of magnesium occurs in which part of the body?

Bone. ***Bone*** - Approximately **50-60%** of the body's total magnesium is stored in the **bone**, largely in conjunction with calcium and phosphate. - Bone magnesium serves as a **reservoir**, helping to maintain stable extracellular magnesium concentrations. *Adipose tissue* - Adipose tissue has a relatively **low concentration of magnesium** compared to other tissues. - Its primary function is energy storage, not mineral storage. *Skeletal muscles* - While skeletal muscles contain a significant amount of intracellular magnesium, accounting for about **20% of total body magnesium**, it is not the *maximum* storage site. - Magnesium in muscle is crucial for **muscle contraction** and energy metabolism. *Blood* - Only about **1% of total body magnesium** is found in the blood. - Blood magnesium is tightly regulated, with free ionized magnesium being the **physiologically active form**.

Acid-Base and Electrolyte Balance — MCQs

Practice by Chapter

Acid-Base Chemistry and Buffers

Practice Questions

pH Regulation in Body Fluids

Practice Questions

Respiratory Regulation of Acid-Base Balance

Practice Questions

Renal Regulation of Acid-Base Balance

Practice Questions

Respiratory and Metabolic Acidosis

Practice Questions

Respiratory and Metabolic Alkalosis

Practice Questions

Mixed Acid-Base Disorders

Practice Questions

Interpretation of Arterial Blood Gases

Practice Questions

Electrolyte Homeostasis

Practice Questions

Sodium and Water Balance

Practice Questions

Potassium Balance

Practice Questions

Calcium and Phosphate Metabolism

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free

Scan to download app