Problem 88 - Objective Biology for NEET

Question

The total filtrate formed in 24 hours in human kidney is (a) \(1.8\) litre (b) \(8.0\) litre (c) 18 litre (d) 180 litre

Step-by-Step Solution

Answer

The total filtrate formed in 24 hours in the human kidney is 180 litres (Option d).

Step 1: Understand Kidney Filtration

In the human kidney system, nephrons do the work of filtering waste out of the blood and creating urine to excrete it. This process is continuous and takes place over a period of 24 hours.

Step 2: Determine the Filtrate Volume

Each day, the kidneys filter out approximately 180 litres of blood to remove waste materials and excess substances. However, most of this is reabsorbed, and only about 1-2 liters is removed as urine each day.

Step 3: Select the Correct Answer

Using the information from step 2, the correct answer can be found. The total filtrate formed in 24 hours in the human kidney is not how much urine is excreted, but how much blood is filtered. So, according to the options provided the correct option is 180 litres, which corresponds to option (d).

Key Concepts

Nephrons

Nephrons are the fundamental working units within the human kidneys. Each kidney contains approximately one million nephrons. These tiny structures are crucial because they perform the essential task of separating waste and excess substances from the blood supply. Nephrons filter blood to form a fluid known as filtrate, which eventually contributes to urine formation.

Let's explore the anatomy of a nephron, as it is composed of several parts, each with a specific role:

• **Glomerulus**: A network of tiny blood vessels where filtration starts.
• **Bowman's Capsule**: Encloses the glomerulus and collects the filtered liquid.
• **Tubules**: Sections where reabsorption and secretion occur, further refining the filtrate.

Each nephron plays a critical role in maintaining the body's delicate balance of water, salts, and waste products. As blood passes through the glomerulus, pressures cause water and solutes to pass into the Bowman's capsule, forming what we call the filtrate. This intricate process underscores the nephron's key function in the body's waste management system.

Filtrate Volume

Filtrate volume refers to the amount of fluid filtered by the kidneys from the blood each day. This volume is quite substantial at about 180 liters daily.

While this number may seem large, it's important to realize that the vast majority of this filtrate is not lost as urine. The filtrate includes water, ions like sodium and chloride, and small molecules such as glucose. Most of these substances are vital for the body's functioning and are reabsorbed back into the blood in the nephron tubules.

Key aspects of filtrate volume include:

• **Reabsorption**: Where the majority of water, electrolytes, and nutrients are reclaimed by the body.
• **Concentration**: The remaining volume becomes concentrated as waste, forming urine.

This efficient system ensures that the body retains what it needs while discarding unnecessary materials, highlighting the importance of reabsorbing most of that impressive initial filtrate volume.

Urine Production

Urine production is the process of transforming the filtrate into urine, the fluid that will ultimately be excreted from the body. Despite generating a filtrate of about 180 liters every day, the actual urine volume is significantly less, amounting to around 1-2 liters per day. This disparity is due to the reabsorption of water and nutrients.

Several steps are involved in turning filtrate into urine:

• **Selective Reabsorption**: Key substances are retained to maintain homeostasis.
• **Tubular Secretion**: Additional waste products are added to the filtrate.
• **Excretion**: The final product, urine, is stored in the bladder until it is eliminated from the body.

Urine's composition largely depends on the body's state and the need to maintain equilibrium. Factors like hydration levels and diet can affect how much urine is produced and its concentration. Overall, urine production effectively Removes waste from the body while carefully balancing bodily fluids.