Function of the liver
- Created by: Steff06
- Created on: 12-03-16 13:09
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- Functions of the liver
- Protein metabolism:
- Production of 3 blood proteins: Fibrinigen, albumin, globulins. Production of urea - linked to deamination.
- TRANSAMINATION = Convert 1 amino acid to another amino acid. DEAMINATION = Removing excess amino acids.
- During DIGESTION, proteins are HYDROLYSED into AMINO ACIDS and transported to the LIVER along HEPATIC PORTAL VEIN.
- Excess amino acids cannot be stored in the liver. Excess undergo DEAMINATION and are also converted into GLUCOSE and TRIGLYCERIDES.
- TRANSAMINATION occurs in the liver. Conversion of 1 amino acid to another - non-essential amino acids are synthesised.
- Stores vitamins and minerals, synthesis and regulation of cholesterol, breaks down hormones, produces urea.
- Produces BILE, amino acids converted to GLUCOSE, protein, lipid and carbohydrate METABOLISM, DEAMINATION/ TRANSAMINATION.
- Formation of urea:
- Produced by liver from excess amino acids. Converted into urea by deamination or urea formation. Transported to KIDNEYS in blood where it is EXCRETED.
- Deamination: AMINE group of amino acids REMOVED. AMMONIA formed - highly SOLUBLE + TOXIC so must be removed. KETO acid enters respiration to release ENERGY or STORED as fat.
- ORNITHINE CYCLE:
- Ammonia converted into LESS soluble + LESS toxic UREA. Urea travels in blood to KIDNEYS Ornithine cycle requires energy from ATP.
- ORNITHINE --> CITRILLINE --> ARGININE
- Ornithine: Ammonia + CO2 in, H20 out.
- Citrilline: Ammonia in, H20 out.
- Arginine: H20 in, urea out.
- O = Amino group + HYDROGEN is removed to form AMMONIA and a KETO ACID.
- C = Highly TOXIC ammonia enters ornithine cycle + converted to UREA. Excess amino acids cannot be stored and undergo DEAMINATION in the liver.
- A = Keto acid either enters RESPIRATORY pathway and generates ATP or it is converted into CARBOHYDRATES or FATS.
- Detoxification: Liver can detoxify many compounds. Can take place by OXIDATION, REDUCTION or METHYLATION of toxins.
- Detoxification of ALCOHOL, ANTIBIOTICS, STEROID HORMONES e.t.c often by action of ENZYMES.
- Protein metabolism:
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