Final answer:
Ammonia formed during amino acid catabolism in muscles is carried to the liver, where it is converted into urea and excreted through the kidneys.
Step-by-step explanation:
Ammonia produced during the catabolism of amino acids in muscles is carried out by the liver. The ammonia generated in the muscles is mainly transferred to the liver in the form of alanine and then converted into urea through the urea cycle, which takes place partly in the mitochondria and partly in the cytosol of hepatocytes. In humans, being ureotelic organisms, urea is the primary waste product derived from nitrogen and is excreted from the body through the kidneys.