What is the most common cation found in the interstitial fluid?

• A. Calcium (Ca2+)
• B. Potassium (K+)
• C. Magnesium (Mg2+)
• D. Sodium (Na+)

Answer: (D)

Verified step by step guidance

1. Understand the concept of interstitial fluid: Interstitial fluid is the fluid that surrounds the cells in tissues, providing them with nutrients and a means of waste removal. It is part of the extracellular fluid compartment.
2. Identify the role of cations in the body: Cations are positively charged ions that play crucial roles in various physiological processes, including nerve impulse transmission, muscle contraction, and maintaining fluid balance.
3. Review the common cations in the body: The major cations in the body include sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+). Each has specific functions and distributions within the body's compartments.
4. Focus on sodium (Na+): Sodium is the most abundant cation in the extracellular fluid, which includes both plasma and interstitial fluid. It is essential for maintaining osmotic balance and fluid distribution.
5. Conclude that sodium (Na+) is the most common cation in interstitial fluid: Given its abundance and role in the extracellular fluid, sodium is the primary cation found in interstitial fluid, making it the correct answer.