Question

Ammonia which is produced by metabolism is converted into A in the liver of mammals and released into B which is filtered and C out by kidney (a) A-Uric acid, B-Blood, C-excreted (b) A-Urea, B-Blood, C-excreted (c) A-Amino acid, B-Blood, C-excreted (d) A-Sugar, B-Blood, C-excreted

Short answer

The correct answer is (b) A-Urea, B-Blood, C-excreted

Step-by-step solution

Understand the Conversion of Ammonia

The metabolism process in mammals produces ammonia, which is toxic. Therefore, the body needs to convert it into a non-toxic form. Among the options, the liver converts ammonia into urea, not uric acid, amino acids or sugar.

Identify the Body Fluid

In all the options, the body fluid into which the product of ammonia conversion is released is the same - 'Blood'. So, there is no dispute over that.

Recognize the Action of the Kidney

Finally, it is known that kidneys are the organ responsible for removing and excreting wastes from the blood. Hence, C must be 'excreted'.

Key concepts

Urea Conversion

Ammonia is a byproduct of the breakdown of proteins in the body, which is a normal part of metabolism. However, ammonia is toxic and needs to be dealt with effectively to prevent harm. Here comes the function of the liver: it converts ammonia into a much less toxic substance called urea. This process is known as urea conversion or the urea cycle.
Urea is a neutral compound, which means it does not carry a charge like ammonia, making it safer to be transported in the blood. The liver plays a crucial role here, ensuring ammonia is safely converted so it can be efficiently removed from the body.

• The conversion takes place in the liver.
• Ammonia is first transformed into an intermediate compound, such as carbamoyl phosphate.
• This intermediate then goes through several steps to form urea, which is less harmful.

This transformation of ammonia to urea involves multiple enzymes and happens continuously as part of normal metabolic processes.

Liver Function

The liver is a vital organ and has many important roles, one of which is detoxification. As we mentioned, it converts ammonia into urea through the urea cycle. But what does this entire process entail? The liver constantly monitors the blood for elevated ammonia levels and kicks off the conversion process quickly.
This continuous monitoring and conversion protect our bodies from the toxic effects of ammonia.
Besides, the liver also handles:

• Protein synthesis, turning amino acids into proteins.
• Managing nutrient storage and release.
• Assisting in digestion through bile production.
• Breaking down old or damaged blood cells.

The liver's ability to convert ammonia ensures that our other bodily functions remain undisturbed by the toxicity of ammonia, highlighting its integral role in maintaining overall health.

Kidney Excretion

Once the liver has done its job converting toxic ammonia into urea, the next essential step is excretion, primarily handled by the kidneys. Kidneys have the crucial role of filtering our blood to remove waste products, excess substances, and toxins.
Urea, now less harmful, circulates in the blood until it reaches the kidneys, which further filter it out to form urine.

• The urea leaves the liver where it travels through circulation.
• The kidneys sense this filtered blood and begin the process of extracting urea.
• Urea is then diluted with water and stored in the bladder until urination.

Through excretion, the body maintains homeostasis, ensuring toxin levels stay safe and normal, thus protecting us from potential harm. This incredible filtering system enables us to keep our internal environment stable, which is essential for all our bodily processes to work efficiently.