Liver

Definition
o        Largest gland associated with the GI Tract
o        1-2 Kg

Location
o        Upper part of the abdominal cavity
o        Occupies the right hypochonndrium
o        Epigastrium
o        Extending  into the left hypochondrium

Surfaces
o        Anterior surface smooth
o        Posterior surface irregular
o         Inferior surface

Relations
o        Anteriorly - diaphragm and anterior abdominal wall
o        Inferiorly - stomach, bile ducts, duodenum, hepatic flexure of the colon, right kidney and adrenal gland.
o        Posteriorly - oesophagus, inferior vena cava, aorta, gall bladder, vertebral column and diaphragm
o        Laterally - lower ribs and diaphragm

Supports
o        Thin capsule   peritoneum
o        Folds of peritoneum attaching the liver to the diaphragm - ligaments
o        Held in position by the ligaments and the pressure of the abdominal organs

Lobes
o        Right lobe
o        Left lobe
o        Quadrate lobe
o        Caudate lobe
       Right lobe is larger than Left lobe

Porta Hepatis
o        It is the door to the liver found on the posterior surface of the liver
o        Portal vein enters
o        Hepatic artery enters
o        Nerves enter - both parasympathetic and sympathetic
o        Right and left hepatic ducts leave liver
o        Lymph vessels leave

Structure
o        Tiny lobules   lobes
o        Lobules - hexagonal - formed by cubical cells called hepatocytes - arranged in columns - radiating from a                     central vein
o        Sinusoid on one side of the column of cells bile canaliculi on the other side of the column of cells.
o        The blood sinusoids contain blood which a mixture of arterial blood and portal venous blood
o        Some cells lining the sinusoids are hepatic macrophages (Kupffer cells).
o        Centrilobular veins -  hepatic veins  - IVC.
o        Bile canaliculi -  right and left hepatic ducts -  porta hepatis -  common hepatic duct.












Functions of liver
o        Synthesis of plasma proteins
o        Synthesis of vitamin A
o        Production of heat
o        Metabolism of alcohol
o        Conversion of glucose to glycogen for storage
o        Storage of fat soluble vitamins: A,D,E, K, iron, copper, some water solble vitamins e.g. riboflavine, niacin pyridoxine, folic acid and vitamin B12
o        Desaturation of fat
o        Deamination of amino acids
o        Transamination  - removing the nitrogenous portion of amino acids and adding it to other carbohydrate molecules forming new non-essential amino acids
o        Breakdown of erythrocytes
o        Detoxification of drugs
o        Inactivation of hormones
o        Secretion of bile to excrete bilirubin
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