Liver:

The liver contributes to excretion by breaking down surplus amino acids and converting them into urea. Urea is a nitrogenous waste product that is transported to the kidneys for removal from the body. Additionally, the liver performs numerous other metabolic functions, including detoxification and the synthesis of important proteins.

Excretory Organs:

Liver its role in producing proteins:

Absorption of Amino Acids: 

Amino acids are the building blocks of proteins and are obtained from the breakdown of dietary proteins. After digestion, amino acids are absorbed into the bloodstream and transported to various tissues and organs, including the liver.

Amino Acid Metabolism in the Liver: 

Upon reaching the liver, amino acids are taken up and processed. The liver has the remarkable ability to regulate amino acid metabolism, ensuring that the body has a balanced supply of amino acids for protein synthesis and other metabolic processes.

Protein Synthesis:

The liver synthesizes various proteins, including plasma proteins like fibrinogen, which plays a crucial role in blood clotting. Through a process called protein synthesis, the liver assembles amino acids into long chains connected by peptide bonds to form functional proteins.

Regulation of Blood Protein Levels: 

The liver helps maintain the proper balance of proteins in the bloodstream by adjusting the rate of protein synthesis based on the body’s needs. This ensures the availability of essential proteins for various physiological functions, such as blood clotting, immune response, and nutrient transport.

The liver and its role in dealing with excess amino acids:

Deamination: 

The liver removes the nitrogen-containing amino group (-NH2) from excess amino acids, resulting in the formation of ammonia (NH3) and keto acid. This process is called deamination and takes place primarily in the liver.

Conversion of Ammonia to Urea:

Ammonia is a toxic compound that must be eliminated from the body. The liver detoxifies ammonia by combining it with carbon dioxide to form urea (CO(NH2)2) through the urea cycle. Urea is a less toxic compound that can be safely excreted from the body.

Utilization of Carbon Skeleton:

 After deamination, the carbon skeleton of the amino acid can be further metabolized. It can be converted into carbohydrates (gluconeogenesis) or lipids (lipogenesis) and used as energy sources or stored for future use.

Excretion of Urea: 

Urea produced in the liver is released into the bloodstream and transported to the kidneys. In the kidneys, urea is filtered out of the blood and excreted from the body through urine. This process helps maintain nitrogen balance in the body.