Physiology Liver

Liver 1.5 kg

detoxifies blood, processes nutrients, and produces bile and proteins essential for digestion and clotting.

Hexagonal functional unit of liver that filters blood and produces essential substances like bile.

Hepatocytes(60%) - perform most metabolic functions Kupffer cells- type of tissue macrophage found in sinusoids liver sinusoidal endothelial cells (LSEC)

specialised porous liver vessel cells that filter waste and regulate nutrient exchange between blood and liver tissue.

blood clotting factors - Fibrinogen Prothrombin Nearly all the other factors e.g. V, VII, IX, X, XII, C

Important depots for storage of fat-soluble vit A, D, E and K Vit Stores Vit B12 and enough stored to last 2-3 years Stores folate, which is required in early pregnancy.

Cholesterol → converts to bile acids in hepatocytes Conjugation with glycine/taurine → bile salts (more water-soluble) Secreted into canaliculi → mix with bilirubin + phospholipids to form bile

Triggered by the hormone cholecystokinin (CCK) during a meal.

stores about 30-50ml bile; has neural & hormonal control

imbalance in the chemical make-up of bile inside the gallbladder

the yellowing of the skin and the whites of the eyes due to an excess of bilirubin in the bloodstream.

To maintain blood glucose Regulation of fat metabolism Regulation of protein metabolism-urea formation Cholesterol synthesis and excretion Synthesis of specialized molecules-bile acids

gastrointestinal tract via the hepatic portal vein

Oxidation through the activity of alcohol dehydrogenase (90%) Microsomal oxidation using cytochrome P450 (10-20%)

Ethanol → Acetaldehyde Enzyme: Alcohol dehydrogenase (ADH) Location: Cytosol Cofactor: NAD⁺ → NADH

Acetaldehyde → Acetate Enzyme: Aldehyde dehydrogenase (ALDH) Location: Mitochondria Cofactor: NAD⁺ → NADH

Acetate → Acetyl-CoA Enzyme: Acetyl-CoA synthetase

Acetyl-CoA enters metabolism Used in Krebs cycle or fat synthesis

highly reactive can inhibit enzyme function. In the liver this can lead to a reduction in the secretion of both serum protein and VLDL - results in fatty liver

1)Fatty liver 2)alcoholic hepatitis, groups of cells die resulting in inflammation 3)Cirrhosis which includes fibrosis, scaring and cell death

High NADH inhibits gluconeogenesis and stimulates lactate production causing lactate acidosis stimulates fatty acid synthesis inhibits TCA cycle

compounds with no nutritional value e.g plant metabolites, cosmetics and food additives

to make xenobiotics harmless and more readily disposed of by the kidney in urine or the gut in faeces