The liver Module 5 Flashcards
Excretion definition?
The removal of waste products of metabolism from the body
Why does the liver need to break down excess amino acids?
Amino acids contain nitrogenous substances, which can’t be stored so have to be broken down and excreted
How are excess amino acids broken down by the liver?
Deamination occurs- Nitrogen containing amino groups (NH2), are removed from excess amino acids, forming ammonia (NH3), and organic acids
The organic acids can be respired to give ATP, or converted to carbohydrate and stored as glycogen
Ammonia is too toxic to be excreted directly, so it’s combined with CO2 in the ornithine cycle
The urea is released from the liver into the blood. The kidneys then filter the blood and remove the urea as urine
How and why does the liver breakdown ethanol?
Toxic substance which can damage cells, excess alcohol can lead cirrhosis of the liver, where liver cells die and scar tissue blocks blood flow
Ethanol is broken down by the liver into ethanal, which is then broken down into acetic acid
Why does the liver break down paracetamol?
If there’s excess in blood, can lead to liver and kidney failure
Why does the liver break down insulin?
Excess in blood as can cause problems with blood sugar levels
What does the liver store?
Converts excess glucose in the blood to glycogen and stores it
Describe the veins, arteries and ducts connected to the liver?
Hepatic artery- provides oxygenated blood
Hepatic vein- takes deoxygenated away from the liver
Hepatic portal vein- Brings blood from the small intestine so rich in products from digestion, meaning any harmful substances are filtered out and broken down straight away
Bile duct- takes bile ( a substance produced by the liver to emulsify fats) to the gall bladder to be stored
What are liver lobules?
What the liver is made up of, cylindrical structures made up of hepatocytes
Each lobule has a central vein running through the middle, that connects to the hepatic vein
Also many branches of the hepatic artery, hepatic portal vein, and bile duc (travelling away from central vein) are connected to each lobule
What connects the hepatic artery and hepatic portal vein to the central vein?
Capillaries called sinusoids
What do sinusoids do?
Allow blood to past the hepatocytes that remove harmful substances and oxygen from the blood
Harmful substances are broken down by the hepatocytes and re-enter the blood as less harmful substances
What do the central veins of all lobules connect up to form?
Hepatic vein
What are Kupffer cells?
Attached to walls of the sinusoids, they remove bacteria and break down old red blood cells
What is the bile duct connected to central vein by?
Tubes called canaliculi
Explain the ornithine cycle?
Ammonia and CO2 combine to form carbonyl phosphate, which combines with ornithine to form citruline
Which then combines with aspartate and ATP to give off AMP and water, and produce arigininosuccinate, which then converts to arginine
Water is added to arginine to produce urea, and ornithine
