5.1.2 (b) the Liver Flashcards
what are the 3 vessels connected to the liver?
hepatic artery
hepatic vein
hepatic portal vein
which vessel removes blood from the liver?
hepatic vein
which vessels bring blood to the liver?
hepatic artery and hepatic portal vein
what is the composition of the blood in the hepatic artery?
this is oxygenated blood from the heart
what is the composition of the blood in the hepatic portal vein?
this is blood containing high concentrations of nutrients from the intestines to allow for metabolic activity in the liver
what cells make up the liver?
hepatocytes
what are the features of a hepatocyte?
they have a large nucleus
they have a prominent golgi complex
they have LOTS of mitochondria
why do hepatocytes have a lot of mitochondria?
they are very metabolically active cells
why do hepatocytes have a prominent golgi?
they have to secrete lots of vesicles of bile
what do hepatocytes do?
break down harmful substances in the blood
break down red blood cells into bile
where is the blood from the hepatic artery and hepatic portal vein mixed in the liver?
spaces called sinusoids are surrounded by hepatocytes
why is the blood mixed in the liver?
this increases the oxygen content of the blood
what are Kuppfer cells?
they are found on hepatocytes and ingest pathogens and protect the liver from disease
where does the bile secreted from the hepatocytes go to?
the Canaliculus which drains the bile into the bile ductiles and then into the gall bladder
micrograph of a liver tissue
what are the main functions of the liver?
carbohydrate metabolism
deamination of amino acids
detoxification
how does the liver react to insulin?
when insulin levels rise due to a high blood glucose level, hepatocytes are stimulated to convert glucose into glycogen
GLYCOGENESIS
so the liver is a good store of glycogen
how does the liver react to glucagon?
when glucagon levels rise due to a low blood glucose level, hepatocytes are stimulated to convert glycogen into glucose
GLYCOGENOLYSIS
what is transamination?
the conversion of one amino acid into another
why is transamination important?
allows diet to be balanced with different amino acids
what is deamination?
the removal of an amine group from a molecule
why must proteins and amino acids be deaminated?
proteins and amino acids cannot be stored in the body
what do hepatocytes produce as a waste product of deamination?
they convert the amino group into ammonia and then into urea
why can’t ammonia just be excreted instead of converting it to urea?
ammonia is too toxic to be excreted directly by mammals
what happens to urea produced in deamination?
transported and excreted by the kidneys
what happens to the rest of the amino acid?
it is used in cellular respiration or converted into lipids for storage
what cycle converts ammonia into urea?
the ornithine cycle
ammonia and carbon dioxide and ornithine
citruline and water
citruline and ammonia
arginine and water
arginine and water
urea and ornithine
generalisation of ornithine cycle
ammonia + carbon dioxide
forms
urea + water
what is detoxification?
when toxic substances are made harmless
what two substances can the liver detoxify?
hydrogen peroxide
ethanol
what enzyme do hepatocytes contain to break down hydrogen peroxide?
catalase
what does catalase split hydrogen peroxide into?
oxygen and water
what enzyme do hepatocytes contain to detoxify ethanol?
alcohol dehydrogenase
what is ethanol broken down into?
ethanal and then to ethanoate
why is it important to detoxify ethanol?
excess ethanol can lead to cirrhosis of the liver
liver cells end up dying
what is wider the hepatic portal vein or hepatic artery?
hepatic portal vein
which is branched hepatic portal vein or hepatic artery?
hepatic portal vein
how are hormones excreted from the body?
hepatocytes remove the NH2 group (deamination)
converts into ammonia
ammonia enters ornthine cycle and urea is formed
urea leaves via the kidney
