15.4 Liver Flashcards
What is excretion?
Excretion is the removal of the waste products of metabolism from the body.
What is the role of the hepatic artery?
The hepatic artery supplies the liver with oxygenated blood from the heart.
What is the role of the hepatic vein?
The hepatic vein carries deoxygenated blood away from the liver and towards the heart.
What is the role of the hepatic portal vein?
The hepatic portal vein carries blood rich in products of digestion straight from parts of the small intestine (duodenum and ileum) so any ingested harmful substances are filtered out and broken down straight away.
What is the role of the bile duct?
The bile duct takes bile to the gall bladder to be stored.
What are hepocytes?
Hepocytes are liver cells.
What are sinusoids?
Sinusoids are capillaries that link the hepatic artery and hepatic portal vein to the central vein.
Why is blood from the hepatic artery and hepatic portal vein mixed in sinusoids?
Mixing increases oxygen content of the blood from the hepatic portal vein, supplying heopcytes with enough oxygen for their needs.
What do sinusoids contain?
Kupffer cells
What is the role of Kupffer cells?
Kupffer cells are attached to the walls of sinusoids and they act as macrophages of the liver, ingesting foreign particles and helping to protect against disease.
How is bile formed?
Bile is formed from the breakdown of haemoglobin from old red blood cells in the liver.
Where do hepocytes secrete bile?
Hepocytes secrete bile into spaces called canuculi, and from these bile drains into bile ductules which take it into gall bladder.
List 3 functions of the liver.
1) Homeostatic control of glucose levels in blood
2) Deamination of excess amino acids
3) Detoxification
How does the liver control glucose levels in the blood?
- When blood glucose levels rise, insulin levels rise and stimulate hepocytes to convert glucose to the storage carbohydrate glycogen.
- When blood glucose levels fall, hepocytes convert glycogen back to glucose under the influence of hormone glucagon.
What is transamination?
Transamination is the conversion of one amino acid into another. This is important because the diet doesn’t always contain the required balance of amino acids but transamination can overcome the problems.
What is deamination?
Deamination is the removal of an amine group from a molecule.
What is the amino group converted into?
AMINO GROUP-> AMMONIA -> UREA
How does the liver break down hydrogen peroxide?
Hepocytes contain the enzyme catalase which breaks down hydrogen peroxide into oxygen and water.
How does the liver detoxify ethanol (active drug in alcoholic drinks)?
Hepocytes contain the enzyme alcohol dehydrogenase that breaks down ethanol to ethanal.
Ethanal is then converted to ethanoate which is used in cellular respiration or to build up fatty acids.
