Problem 126 - Objective Biology for NEET

Question

Which is not a part of renal tubule? (a) \(\mathrm{PCT}\) (b) Bowman's capsule (c) DCT (d) Collecting duct

Step-by-Step Solution

Answer

The part of the nephron which does not belong to the renal tubule is the Bowman's capsule. So, option (b) is the correct choice.

Step 1: Analyze the parts of the nephron

A nephron consists of a renal corpuscle, a renal tubule, and the associated capillaries. The renal corpuscle includes the glomerulus and Bowman's capsule. The renal tubule includes the proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and collecting duct. The renal tubule extends from the renal corpuscle to the collecting ducts.

Step 2: Identify the part not in the renal tubule

From step 1, we can clearly see that the Bowman's capsule is a part of the renal corpuscle, whereas the PCT, DCT, and collecting duct are parts of the renal tubule.

Key Concepts

Renal Tubule

The renal tubule plays a crucial role in the kidney's ability to filter blood, reabsorb vital nutrients, and secrete waste products. It is an intricate structure consisting of various segments, each with a specific function in urine formation. The renal tubule begins at the renal corpuscle and extends through to the collecting duct.

• Proximal Convoluted Tubule (PCT): The segment immediately following the renal corpuscle. It's primarily responsible for reabsorbing nutrients like glucose and amino acids, along with a significant amount of water and ions.
• Loop of Henle: A U-shaped structure that dips into the renal medulla. It functions in creating a concentrated urine by reabsorbing water and salts with its descending and ascending limbs.
• Distal Convoluted Tubule (DCT): This segment continues the process of selective reabsorption and secretion, balancing electrolytes and water.
• Collecting Duct: The terminal part of the renal tubule, where final urine concentration occurs, before it's passed to the renal pelvis.

The renal tubule is essential in fine-tuning the composition of urine, ensuring that the body maintains homeostasis while efficiently eliminating waste.

Renal Corpuscle

At the beginning of a nephron, you'll find the renal corpuscle. This structure is critical for the initial filtering of blood. It is composed of two main parts: the glomerulus and Bowman's capsule. Located within the renal cortex, the renal corpuscle efficiently starts the process of urine formation by filtering blood.

• Glomerulus: A network of capillaries that filters blood, allowing water and small molecules to pass while retaining blood cells and larger proteins.


• Bowman's Capsule: Serves as the surrounding cup-like sac that catches the filtered fluid, known as filtrate, from the glomerulus. This filtrate then enters the renal tubule for further processing.

By ensuring adequate filtration, the renal corpuscle initiates the body's ability to manage waste products and maintain fluid and electrolyte balance.

Bowman's Capsule

Bowman's capsule is a vital component of the renal corpuscle and acts as the entry point for kidney filtration. When blood pressure forces fluid through the glomerulus, the filtrate is captured by Bowman's capsule. This structure ensures that the initially filtered substances, also known as the glomerular filtrate, are transferred smoothly into the renal tubule for further processing.

• The capsule itself is a thin-walled structure composed of epithelial cells.
• The close proximity to the glomerulus allows Bowman's capsule to effectively perform its role.

By passing the filtrate into the renal tubule, Bowman's capsule helps maintain the body’s internal environment, clearing blood of toxins and excess substances efficiently. By understanding Bowman's capsule and its function, we gain insight into how our kidneys manage complex filtration processes every minute of the day.