The Liver Flashcards
Functions of the liver
What role does the liver play in storage
Examples of harmful substances the liver detoxes
Alcohol
H2O2
Lactate
Drugs
Hormones
How does the liver detoxify harmful substances (general)
-> oxidised / reduced / methylated etc. using enzymes
E.g. catalases converts H2O2 to H2O & O2
E.g. cytochrome P450 (a group of enzymes) breaks down drugs like cocaine, & is used in metabolic reactions like transport
How does the liver detoxify alcohol steps
- Alcohol broken by ethanol dehydrogenase, forming ethanal
- Ethanal further dehydrogenated to form the ethanoic acid with ethanoate
- Ethanoate/Acetate combines with CoA to form acetyl CoA
How does the liver detoxify lactate
- Converted to pyruvate
-> some enters the mitochondria for aerobic respiration
-> provides energy for the rest of the lactate to be converted to glucose - So some converted to glucose
-> then stored as glycogen
-> or enters blood to maintain blood glucose concentration
Role of NAD in detoxification
Typically used in lipid processing
- oxidised & breakdown fatty acids so they can be used in respiration
What is liver cirrhosis
The scarring of liver tissue caused by excess alcohol consumption -> death of liver tissue
How does liver cirrhosis happen
Ethanol respired by hepatocytes instead of fat
-> extra fat stored (leads to fatty liver condition)
Reducing ability of hepatocytes to function
Therefore, leading to cirrhosis
What is present in the liver to lead to the formation of urea
Amino acids
Why are there amino acids in the liver
Proteins in diet digested to amino acids
Amino acid absorbed into the bloodstream & transported to liver
Why are excess amino acids not excreted or stored
Not excreted = as they contain a lot of energy
Not stored as they make amino acids toxic
So what happens to excess amino acids in the liver
Treated (converted to urea) to remove and excrete the amino component (deanimation & the ornithine cycle)
What happens in deanimation
What happens in the ornithine cycle
(Extra) After urea transported to the kidneys, the kidneys filter urea out of the blood, & into the urine, and the urine is stored in the bladder until released from cycle
What does the liver do
Break down unwanted & toxic substances & produce excretory waste
Liver diagram
Liver diagram
4 liver vessels?
Hepatic vein
Hepatic portal vein (blood supply)
Hepatic artery (blood supply)
Bile duct
What does the hepatic vein do
Carries deoxygenated blood from the liver (to the vena cava) & them to the heart
What does the hepatic portal vein
What does the hepatic artery do
Supplies oxygenated blood from the heart & oxygen for aerobic respiration
What does the bile duct do
Carries bike from liver -> gallbladder
- the gall bladder = where bile is stored!
Bile emulsifies fats in the small intensive, & neutralises stomach acid
Why does the liver require a constant blood supply
As it supplies the oxygen needed for a high rate of aerobic respiration
+ as hepatocytes are very active (carry out many metabolic processes)
What are hepatocytes & features
- liver cells
- very dense cytoplasm
- regenerate by mitosis
- many metabolic functions
- large SA in contact with blood
# maximise exchange of substances
Hepatocytes Sinusoids & central vein diagram
What are sinusoids
- wide capillaries in which blood is carried (blood from the hepatic artery & portal vein mix)
-> lined with incomplete layers of endothelial cells & hepatocytes - allowing blood to reach hepatocytes for substance exchange between them
@ the end of the sinusoid, concentrations of substances in blood have been modified & regulated
-> enter branch of hepatic vein
Liver lobule features
Section of a lobule diagram
What is the bile canaliculus
- surrounded by hepatocytes which produce bile
-> connect to drain bile into the bile duct
What are kupffer cells
Specialised macrophages
-> destroy pathogens before they can travel any further
- breakdown + recycle old red blood cells
N = central vein
O = hepatocyte
