15.4 The Liver Flashcards
(29 cards)
define excretion
the removal of waste products of metabolism from the body
what are the 3 main metabolic waste products in mammals
- CO2
- bile pigments
- nitrogenous waste products (urea)
what is CO2 a waste product of
cellular respiration which is excreted from the lungs
how are bile pigments formed
from the breakdown of haemoglobin from old RBCs in the liver
where are bile pigments excreted from and into
the liver into the small intestine via the gall bladder and bile duct
how are nitrogenous waste products formed
from the breakdown of excess amino acids by the liver
what is the nitrogenous waste product in mammals
urea
what is the nitrogenous waste product in fish
ammonia
what is the nitrogenous waste product in birds and insects
uric acid
explain the blood supply to the liver
- oxygenated blood is supplied by the hepatic artery and removed by the hepatic vein
- the hepatic portal vein carries blood with products from digestion from the intestine to the liver
- 75% comes via the hepatic portal vein
explain the characteristics of hepatocytes
- large nuclei
- prominent Golgi apparatus
- lots of mitochondria
- divide and replicate very quickly
what are sinusoids
spaces where blood from the hepatic artery and the hepatic portal vein get mixed (increases oxygen content of blood from the HPV)
what do sinusoids contain
Kupffer cells
what do Kupffer cells do
act as resident macrophages by ingesting foreign particles and protecting it against disease
what do the hepatocytes secrete
- bile from the breakdown of blood into spaces called canaliculi
- then bile drains into the bile ductule which go to the gall bladder
what are the 3 main function of the liver
- carbohydrate metabolism
- deamination of excess amino acids
- detoxification
explain carbohydrate metabolism (blood glucose rises)
- blood glucose levels rise = insulin levels rise = hepatocytes convert glucose –> glycogen (storage)
what is transamination
conversion of one amino acid into another
why is transamination important
overcomes the problems of the diet which doesn’t always contain the required balance of amino acids
what is deamination
the removal of an amine group from a molecule
explain the process of deamination
- hepatocytes remove the amino group and convert amino acids –> ammonia –> urea
what happens to the remaining amino acids after deamination
- fed into cellular respiration
- converted into lipids for storage
what does the ornithine cycle do
convert ammonia into urea
how is hydrogen peroxide broken down
hepatocytes contain catalase which splits the hydrogen peroxide into oxygen+water
