Arrange the following step in sequence of involvement during uropoiesis :
(A) Concentration of urine
(B) Ultrafiltration
(C ) Secretion
(D) Reabsorption

Options

A. `BtoDtoCtoA`
B. `BtoDtoAtoC`
C. `DtoBtoCtoA`
D. `DtoCtoBtoA`

Answer

To arrange the steps involved in uropoiesis in the correct sequence, we need to understand the processes that occur in the kidneys during urine formation. Here’s a step-by-step breakdown:

### Step-by-Step Solution:

1. **Ultrafiltration (B)**: The first step in uropoiesis is ultrafiltration, which occurs in the glomerulus of the nephron. Blood pressure forces water, ions, and small molecules from the blood into the Bowman's capsule, forming the filtrate.

2. **Reabsorption (D)**: After ultrafiltration, the filtrate moves into the renal tubule, specifically the proximal convoluted tubule, where reabsorption occurs. Essential substances like glucose, amino acids, and certain ions are reabsorbed back into the bloodstream.

3. **Secretion (C)**: Following reabsorption, the next step is secretion. In this process, additional waste products and excess ions are secreted from the blood into the renal tubule, further refining the composition of the urine.

4. **Concentration of Urine (A)**: Finally, the urine is concentrated as it passes through the loop of Henle and the collecting ducts. Here, water is reabsorbed, and the urine becomes more concentrated before it is excreted.

### Final Sequence:
The correct order of steps in uropoiesis is:
- (B) Ultrafiltration
- (D) Reabsorption
- (C) Secretion
- (A) Concentration of urine

### Answer:
The correct sequence is **B, D, C, A**.

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