**Question:** Cells of kidney having secretory function

**Core Concept:** Renal tubules are the key functional units of the nephron, responsible for reabsorption, secretion, and excretion of ions, water, and substances.

**Why the Correct Answer is Right:** The correct answer refers to the cells found in the renal tubules that have a secretory function. These cells, specifically the **proximal tubule cells** and **distal tubule cells**, are specialized to perform this function. They actively transport ions, water, and other substances, contributing to the overall renal functions such as maintaining electrolyte balance, acid-base homeostasis, and osmoregulation.

**Why Each Wrong Option is Incorrect:**

A. **Nephron cells:** This option is incorrect because nephron cells are the basic functional unit of the kidney, not specifically targeting the cells with secretory function.

B. **Pulmonary cells:** This option is incorrect as it refers to cells found in the lungs, not the kidney.

C. **Hepatic cells:** This option is incorrect as it refers to cells found in the liver, not the kidney.

D. **Neuroendocrine cells:** This option is incorrect as it refers to cells involved in hormone secretion, not renal tubule cells with secretory function.

**Clinical Pearl / High-Yield Fact:** The renal tubules are crucial for maintaining homeostasis, and understanding their function is essential for medical students and practicing physicians alike. A working knowledge of renal tubular cells and their specific roles allows for accurate diagnosis and treatment of various kidney diseases that involve tubular dysfunction.

**Correct Answer:** D. Nephron cells (proximal tubule cells and distal tubule cells)

These cells play a vital role in the kidney's ability to maintain electrolyte balance, acid-base homeostasis, and osmoregulation. They are responsible for reabsorbing essential substances while excreting waste products and excess substances, ensuring that the body maintains proper fluid and electrolyte balance.