Liver Flashcards
Hepatocytes
Make up the liver
Hepatic artery
Branches off from the aorta and brings oxygen-rick blood from heart
Hepatic portal vein
Brings nutrient-rich deoxygenation blood from the stomach and intestines
Composition of the hepatic portal vein in liver
The hepatic portal vein subdivides into branches and then sinusoids. Sinusoids are similar to capillaries, but are wider and their walls are not continuously lined with cells allowing for the blood to come in close contact with the hepatocytes to exchange materials. The sinusoids drain into a central vein, which is a branch of the hepatic vein
Composition of the hepatic artery in liver
Subdivides into branches and then capillaries which join with the sinusoids providing hepatocytes with oxygenated blood
Detoxification
Removes toxins from the blood and converts them to non-toxic or less toxic substances. They are by-products of metabolism or foreign chemicals such as drugs and poisons. The liver does this by converting hydrophobic compounds into hydrophilic compounds that more easily excreted
Breakdown of erythrocytes
Ages erythrocytes are removed from the circulation by Kupffer cells. Kupffer cells are macrophages- the phagocytose and break down RBCs. Inside the Kupffer, the heamoglobin splits into globin chains and heme group. The globin chains are hydrolysed to aa, which are released into the blood and can be used for protein synthesis. The heme group breaks down into iron and the yellow pigment bilirubin. Kupffer cells release most iron into the blood. The blood carries iron to the bone marrow where it is used for production of new erythrocytes. Some of the iron is transported to the liver for storage.
Synthesis of cholesterol and conversion of cholesterol to bile salts
Cholesterol is absorbed from food in the intestine and is synthesised by hepatocytes if amounts in the diet are insufficient. Hepatocytes convert cholesterol to bile salts. Bile salts are part of the bile that is produced in the liver.
Production and secretion of bile
Bile is a green-brown fluid mixture that amongst others contains bile salts, bilirubin, bicarbonate and lipids. Hepatocytes secrete the bile into a network of bile canniculi which carry the bile from the liver to the gall bladder.
Production of plasma proteins
Hepatocytes produce 90% of the blood plasma proteins such as fibrinogen and albumin. Plasma proteins are synthesised in ribosomes of the rER and are processed by the Golgi apparatus.
Nutrient regulation and storage
Blood that has passed through the wall of the intestine flows via the hepatic portal vein into liver sinusoids where it is in close contact with hepatocytes. Hepatocytes regulate the levels of nutrients. Some nutrients are converted into forms that be used or stored. Some nutrients in excess are stored eg. glucose, vitamin D, vitamin A and iron
Amino acids storage
The body cannot store amino acids so any excess is broken down in hepatocytes. Hepatocytes can also synthesise non-essential amino acids
Lipids storage
Major site of synthesise of many lipids and also manages circulating lipids. Lipids are then stored by the liver or transported to cells by different types of lipoproteins. Hepatocytes also convert surplus cholesterol into bile salts.
Jaundice
Condition when bilirubin builds up in the blood. Symptom: yellowing of the eyes due to excess bilirubin. It is not a disease itself but is a symptom of many disorder that interfere with the metabolism or secretion of bilirubin. eg. liver diseases like hepatitis, obstruction of the bile duct by gallstones and excessive breakdown of RBCs.
Jaundice in new-borns is common because they have high turnover of RBCs. The liver is still developing and may not be able to process the bile pigment fast enough. Some newly born infants do not feed properly.
If the levels of bilirubin remain elevated, brain damage that results in deafness and cerebral palsy.
Adult patients usually experience itchiness
Treatment: exposure to UV light
