• Many digested food molecules absorbed into the blood in the small intestine are carried to the liver for?assimilation?(when food molecules are converted to other molecules that the body needs)
• These include amino acids, which are used to build proteins such as?fibrinogen, a protein found in blood plasma that is important in blood clotting
• Excess amino acids?absorbed in the blood that are not needed to make proteins?cannot be stored, so they are broken down in a process called?deamination
  • The amino group of all? amino acids - NH₂?(which contains the nitrogen atoms) is removed, hence the term de-amin(o)-ation
• Enzymes in the liver split up the amino acid molecules
• The part of the molecule which contains?carbon?is turned into?glycogen?and stored
• The other part, which contains?nitrogen, is turned into?ammonia, which is highly toxic, and so is immediately converted into?urea, which is less toxic
• The urea dissolves in the blood and is taken to the?kidney?to be excreted
• A small amount is also excreted in?sweat

Amino acid groups

• In deamination, the nitrogen-containing amino group is removed and converted into ammonia and then urea to be excreted
• The toxic consequences of high urea levels, if it is not excreted effectively, are very serious:
  • Cell death
  • Reduced response to insulin, leading to diabetes
  • Deposits inside blood vessels