Substances like glucose, amino acid `NA^(+)` etc. in the filtrate are reabsorbed by

Options

A. Active transport
B. Passive transport
C. Both active and passive transport
D. Facilitated diffusion

Answer

**Step-by-Step Solution:**

1. **Understanding Filtration in the Kidney:**
- Blood is filtered in the kidneys through a structure called the glomerulus, which is a tuft of capillaries. This process occurs in the Bowman's capsule, where the filtered fluid is known as glomerular filtrate.

2. **Components of Glomerular Filtrate:**
- The glomerular filtrate contains various substances, including glucose, amino acids, sodium ions (Na+), and other small molecules. These substances are essential for the body's metabolic processes.

3. **Reabsorption Process:**
- After filtration, the glomerular filtrate moves into the renal tubules, where reabsorption occurs. The renal tubules consist of different segments, including the proximal convoluted tubule (PCT), loop of Henle, and distal convoluted tubule (DCT).

4. **Mechanisms of Reabsorption:**
- There are two main mechanisms through which substances are reabsorbed from the filtrate back into the bloodstream:
- **Passive Transport:** This process does not require energy and occurs when substances move from an area of higher concentration to an area of lower concentration. It primarily involves the reabsorption of ions like Cl-, HCO3-, urea, and a significant amount of water.
- **Active Transport:** This process requires energy (ATP) and involves the movement of substances from an area of lower concentration to an area of higher concentration. This mechanism is crucial for reabsorbing nutrients such as glucose, amino acids, and ions like Na+ and K+.

5. **Conclusion:**
- Given that glucose, amino acids, and Na+ ions are reabsorbed from the filtrate, the correct answer to the question is that these substances are reabsorbed by **active transport**.

**Final Answer:**
Substances like glucose, amino acids, and Na+ in the filtrate are reabsorbed by **active transport**.

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