The liver and excretion Flashcards
What is excretion
Excretion is the removal of waste products of metabolism from the body
what are some examples of excretory organs that remove CO2
In mammals: lungs
In Fish: gills
What is the livers role
To break down excess amino acids
Why does the liver breakdown excess amino acids
- This is because Nitrogenous substances can’t be stored in the body.
- So excess amino acids damage the body: so they must be used by the body, broken down or excreted
What is deamination
When amino groups are removed from excess amino acids- forming ammonia and organic acids
Process: how are excess amino acids broken down
1) The excess amino acids first undergo deamination
2) The organic acids produced from deamination, are then respired to give ATP.
OR they are converted to carbohydrates to be stored as glycogen.
3) Ammonia combines with CO2 in the ornithine cycle to create urea
- Urea is then released from the liver into the blood and the kidneys filter the blood and remove the urea as urine.
As well as amino acids, what else does the liver break down ?
Alcohol, paracetamol and insulin
- insulin is a hormone that controls blood glucose concentration, excess insulin causes problems with blood sugar levels
- excess paracetamol can lead to liver and kidney failure
What is the process of the liver breaking down harmful substances called
Detoxification
The liver breaks down ethanol into……………, which then breaks down into………………
1) ethanal
2) acetic acid
what is cirrhosis of the liver
This is when liver cells die
and the scar tissue blocks blood flow
what is glycogen stored as until it is needed for energy?
Its stored as granules in liver cells, until the glucose is needed for energy
What does the hepatic artery do?
Supplies the liver with oxygenated blood from the heart
So the liver has a good supply of oxygen needed for respiration.
What does the hepatic vein do?
Takes deoxygenated blood away from the liver
What does the hepatic portal vein do?
Brings blood from the duodenum and the ileum, which is rich from products of digestion.
Any harmful ingested substances are filtered out and broken down straight away
What does the bile duct?
Takes bile to the gall bladder where it is stored
what are hepatocytes?
Cells that MAKE UP liver lobules (cylindrical structures radiating out of the central vein)
Hepatocytes remove harmful substances and oxygen from the blood.
What do all the central veins connect to form?
It connects to form the hepatic vein
How are is the hepatic portal vein and hepatic artery connected to the central vein?
Connected by capillaries called sinusoids
where are Kupffer cells found and what do they do?
Kuppfer cells are attached to the walls of the sinusoids
They remove bacteria and break down old red blood cells
What produces bile and where is it secreted into?
Hepatocytes produce bile and secrete it into the bile canaliculus, theses tubes then drain into bile ducts,
Eventually, all the bile ducts from all the lobules connect up and leave the liver.
When observing a micrsope diagram of the liver
The large white circle is the central vein
The little white spaces are the sinusoids
The cells that radiate out from the central vein are the hepatocytes
The little black dots are nuclei
- microscopes slides normally stained with eosin or haematoxylin, to see the cells easier.
