Which of the following substances are secreted during tubular secretion in the kidneys?

• A. Sodium ions
• B. Amino acids
• C. Glucose
• D. Hydrogen ions

Answer: (D)

Verified step by step guidance

1. Understand the process of tubular secretion: Tubular secretion is a part of the kidney's function where substances are transferred from the blood into the renal tubule. This process helps in maintaining the body's acid-base balance and removing excess substances.
2. Identify substances typically secreted during tubular secretion: Common substances secreted include hydrogen ions, potassium ions, and certain drugs or toxins. These are actively transported into the tubular fluid.
3. Consider the role of hydrogen ions: Hydrogen ions are secreted to help regulate the body's pH balance. This is crucial for maintaining homeostasis and preventing acidosis.
4. Evaluate the other substances listed: Sodium ions, amino acids, and glucose are typically reabsorbed rather than secreted. Sodium ions are reabsorbed to maintain electrolyte balance, while amino acids and glucose are reabsorbed to conserve energy and nutrients.
5. Conclude with the correct answer: Based on the understanding of tubular secretion, hydrogen ions are indeed secreted during this process, aligning with the body's need to regulate pH levels.