Human kidneys can produce urine nearly concentrated than the initial filtrate formed

Options

A. 1/5 times
B.  10timesÂ
C.  5 times
D. 4timesÂ

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks how human kidneys can produce urine that is more concentrated than the initial filtrate formed.

2. **Role of Kidneys**: The kidneys are responsible for filtering blood and forming urine. This process involves the nephrons, which are the functional units of the kidneys.

3. **Filtration Process**: Blood enters the nephron through the afferent arteriole and reaches the glomerulus, a network of capillaries. Here, the first filtration occurs, where water, salts, glucose, and nitrogenous wastes (like urea and uric acid) pass through, while larger molecules (like proteins and blood cells) are retained.

4. **Formation of Initial Filtrate**: The fluid that passes through the glomerulus is called the initial filtrate. This filtrate contains waste products, water, and other small molecules.

5. **Reabsorption and Secretion**: After the initial filtration, the filtrate moves through various parts of the nephron, including the Proximal Convoluted Tubule (PCT), Loop of Henle, Distal Convoluted Tubule (DCT), and collecting duct. During this process, significant amounts of water, salts, and nutrients are reabsorbed back into the bloodstream.

6. **Concentration of Urine**: The Loop of Henle plays a crucial role in concentrating urine. It creates a concentration gradient in the medulla of the kidney, allowing for the reabsorption of water. The more water that is reabsorbed, the more concentrated the urine becomes.

7. **Final Urine Concentration**: By the time the filtrate reaches the collecting duct, it can be concentrated to a level that is nearly four times more than the initial filtrate. This means that the kidneys can produce urine that is significantly more concentrated than the original filtrate.

8. **Conclusion**: Therefore, the human kidneys can produce urine that is nearly four times more concentrated than the initial filtrate formed, confirming the statement in the question.