The Liver Flashcards
The hepatic artery
Oxygenated blood travels from he heart to the hepatic artery and into the liver. This supplies oxygen for aerobic respiration.
The hepatic portal vein
Deoxygenated blood from the digestive system enters the liver via the hepatic portal vein containing products of digestion. It may also contain toxic compounds.
The hepatic vein
Blood leaves the liver via he hepatic vein and rejoins the vena cava.
At the centre of each lobule is a branch of the hepatic vein known as the intra lobular vessel.
Bile duct
Carries bile from the liver to the gall bladder where it is stored. Bile aids the digestion of fats. It also contains excretory products such as the pigment bilirubin.
Bile is made in the liver cells and released into the bile canaliculi which form the bile duct.
Kupffer cells
- specialised macorphages
- move around within the sinusoids
- break down and recycle old red blood cells
Meatbolic functions of the liver
- control of blood glucose, amino acid and lipid levels
- synthesis of bile, plasma proteins and cholesterol
- synthesis of red blood cells in he fetus
- storage of vitamins, iron and glycogen
- detoxification of alcohol and drugs
- breakdown of hormones
- destruction of red blood cells
Detoxification of hydrogen peroxide
Catalase converts hydrogen peroxide to oxygen and water. It has a very high turnover number.
Detoxification of alcohol
- Ethanol is broken down in the hepatocytes by the enzyme ethanol dehydrogenase to produce ethanal and NADH
- Ethanal is dehydrogenated by ethanol dehydrogenase producing ethanoate and NADH
- Acetate combines with coenzyme A to form acetyl coenzyme A which enters aerobic respiration
Fatty liver and cirrhosis
If there is too much alcohol, it uses up NAD stores so there isn’t enough to deal with the fatty acids. These are then converted to lipids and stored in the hepatocytes. This causes fatty liver and can lead to cirrhosis.
Deamination
Amino group is removed from amino acid producing ammonia and a keto acid. The keto acid enters respiration.
The ornithine cycle
- Ammonia is combined with carbon dioxide with the amino acid ornithine to produce citrulline.
- Further ammonia is added to produce arginine
- Arginine is converted to ornithine as urea is removed
- ammonia + carbon dioxide –> urea + water
