The liver is the primary organ that destroys excess protein in the body.
The liver plays a central role in amino acid metabolism. When the body has more protein than it needs for building and repairing tissues, the excess amino acids are broken down in a process called amino acid catabolism. This process primarily occurs in the liver.
Here's a breakdown of what happens:
- Deamination: The liver removes the amino group (-NH2) from the amino acid. This amino group is converted into ammonia, which is toxic.
- Urea Cycle: The liver converts the toxic ammonia into urea through the urea cycle. Urea is much less toxic and can be safely transported in the blood.
- Excretion: The kidneys filter the urea from the blood and excrete it in urine.
- Carbon Skeleton Fate: The remaining carbon skeleton of the amino acid can be used for energy production (through cellular respiration) or converted into glucose (gluconeogenesis) or fat (lipogenesis) for storage.
While the liver is the primary site, muscle cells also play a role in the catabolism of branched-chain amino acids.
In summary, the liver's crucial functions in amino acid metabolism include deamination, urea synthesis, and processing the resulting carbon skeletons. These actions make it the principal organ for managing and eliminating excess protein.
