Urea formation occurs in the

Explanation

The functions of the heart are to pump blood and oxygen around the body and deliver waste products (carbon dioxide) back to the lungs to be removed. 

Urea is produced in the liver:  

• Production: The liver produces urea through a series of biochemical reactions called the urea cycle. The urea cycle converts ammonia, a toxic waste product from the breakdown of amino acids, into urea, which is nontoxic and water-soluble.  
• Transport: Urea is dissolved into the blood and transported to the kidneys.  
• Excretion: The kidneys excrete urea in urine along with water and other waste products. 

There is an explanation video available .