Problem 159 - Objective Biology for NEET

Question

Assertion: In vertebrates, the liver is also referred as an accessory excretory organ. Reason: Liver helps kidneys in the secretion of urine.

Step-by-Step Solution

Answer

The assertion is correct, the liver can be considered an accessory excretory organ in vertebrates. However, the reason given is only partially correct - while the liver does process waste that gets excreted through urine, it doesn't directly assist the kidneys in urine secretion.

Step 1: Examining the Assertion

The assertion states that in vertebrates, the liver is known as an accessory excretory organ. This implies that the liver plays a role in the excretion process.

Step 2: Understanding the Role of the Liver

The liver is an important organ involved in several major functions within the body including detoxification, protein synthesis, and production of bile which helps in digestion. It also aids in the excretion of waste material from body, thus it can be linked as an accessory excretory organ.

Step 3: Analyzing the Reason

The reason states that the liver helps the kidneys in the secretion of urine. Kidneys are the primary organ responsible for urine production. The liver does not directly help in urine secretion, but it does process metabolic waste and toxins which are eventually excreted through the urine.

Step 4: Assessment

Based on steps 1 to 3, the assertion is found to be correct. The liver is indeed an accessory excretory organ. However, the reason is partially correct: while the liver processes waste and toxins that are excreted in urine, it does not directly assist the kidneys in urine production.

Key Concepts

Role of Liver in Excretion

The liver is a critical organ that performs various essential functions in our body. One of its significant roles is aiding the excretion of waste products. While the primary function of the liver is to process nutrients from what we consume, it's also involved in detoxifying and breaking down harmful substances.
These substances include drugs, alcohol, and metabolites produced by cellular activities. After detoxification, the liver converts these byproducts into less harmful forms, readying them for excretion. It's this particular function that helps it earn the title of an accessory excretory organ.

• The liver helps remove excess amino acids, converting them into ammonia.
• It further processes ammonia into a less toxic compound called urea.
• This urea is then released into the bloodstream and filtered out by the kidneys.

Although the liver does not directly expel waste from the body, its role in detoxification and conversion of harmful substances is crucial, supporting the kidneys in their excretory function.

Kidney Function

The kidneys are vital organs in the human body, primarily responsible for purifying the blood by eliminating waste products and excess substances. Our kidneys act like a sophisticated filtering system that maintains the body's internal environment.

• They filter blood, removing unwanted substances and conserving necessary ones.
• They help balance the body's fluids and electrolytes.
• They regulate blood pressure and produce hormones that are essential for other functions.

The kidneys work continuously to filter and purify blood. As blood flows through the kidneys, these organs selectively reabsorb necessary nutrients and water, all while excreting waste products in the form of urine.
Kidneys receive processed waste from the liver, like urea, to be filtered and excreted from the body. This synergy ensures that metabolic byproducts are effectively expelled, maintaining homeostasis.

Metabolic Waste Processing

The body constantly generates waste products through metabolic processes. Metabolic waste refers to any byproduct that must be expelled from our bodies to maintain health. These are typically substances left over from cellular respiration or nutrient breakdown.

• Carbon dioxide, a byproduct of respiration, is expelled via the lungs.
• Urea, formed from excess amino acids, is processed by the liver and excreted by the kidneys.
• Other metabolites, from digestion and cellular metabolism, are filtered out by kidneys.

The liver plays a pivotal role in detoxifying blood and breaking down proteins into urea. This particularly is part of the urea cycle, essential for removing nitrogen waste.
Once processed, these substances enter the bloodstream and eventually reach the kidneys, which complete the excretion through urine.
This collaboration between the liver and kidneys ensures the body's waste is effectively managed, highlighting the importance of each organ in maintaining a healthy internal environment.