What are the components of renal tubule as they encountered by filtrate?

As the filtrate passes through the renal tubule, it encounters several components in the following sequence:

1. Proximal Convoluted Tubule (PCT):

- The PCT is the first and longest segment of the renal tubule.

- It is responsible for the reabsorption of essential substances, including glucose, amino acids, vitamins, and water.

- Active reabsorption of sodium ions occurs in the PCT, which drives the reabsorption of other solutes.

- The PCT also plays a role in regulating pH balance by secreting hydrogen ions (H+) and reabsorbing bicarbonate ions (HCO3-).

2. Proximal Straight Tubule (PST):

- The PST is a short segment that connects the PCT to the loop of Henle.

- It continues the reabsorption processes initiated in the PCT and further concentrates the filtrate.

3. Loop of Henle:

- The loop of Henle consists of a descending limb and an ascending limb.

- The descending limb is responsible for further water reabsorption, making the filtrate more concentrated.

- The ascending limb is impermeable to water but actively reabsorbs sodium and chloride ions, creating a concentration gradient in the medulla.

4. Distal Convoluted Tubule (DCT):

- The DCT is the next segment encountered by the filtrate after the loop of Henle.

- It fine-tunes the composition of the filtrate by selectively reabsorbing or secreting ions, such as sodium, potassium, chloride, and hydrogen ions.

- The DCT also plays a role in calcium and magnesium homeostasis.

5. Connecting tubule:

- The connecting tubule is the final segment of the renal tubule before the collecting duct.

- It has minimal reabsorption or secretion and mainly serves as a passageway for the filtrate.

6. Collecting Duct:

- The collecting duct receives filtrate from multiple nephrons and merges them into a single stream of urine.

- It is responsible for fine-tuning the water and electrolyte balance based on the body's needs.

- The collecting duct responds to various hormones, including antidiuretic hormone (ADH) and aldosterone, which regulate water and sodium reabsorption, respectively.

These components of the renal tubule work together to modify the filtrate, reabsorb essential substances, and regulate water and electrolyte balance, eventually forming urine that is excreted from the body.