The Liver Flashcards
What are the 6 roles of the liver
1) blood glucose regulation
2) bile drainage
3) blood circulation and filtration
4) detoxification (drugs, alcohol and hydrogen peroxide)
5) synthesis and storage of amino acids acids, proteins, vitamins and fats
6) control lipid levels
What is the liver linked to
1) the intestine
2) gall bladder
Why does the liver need to be linked to the intestine
So waste products can be taken to the liver for detoxification
Why does the liver need to be linked to the gall bladder
To take the bile out of the liver
Which storage molecules is required for glucose storage
Glycogen
What are the 4 vessels within the liver
1)hepatic vein (central vein)
2) hepatic artery
3) hepatic portal vein
4) bile duct
What if the function of the hepatic artery
-brings oxygenated blood into the liver from the aorta
-aerobic respiration
What is the function of the hepatic portal vein
-brings deoxygenated blood from the digestive system
-has products of digestion and toxic substances and concentrations get adjusted
What are the functions of the hepatic vein
-where blood leaves the liver
-rejoins vena cava for normal circulation
What is the function of the bile duct
-bile secreted and carried to gall bladder to be stored until needed for emulsification of fats in the small intestine
-contains excretory products released in faces
What are lobes
The sectioning of the liver into left and right lobe
What are lobules
-small cylindrical sections within each of the lobes
-they have their own blood supply and are structures to maximise the number of cells in contact with this blood
What are cells in the liver called
Hepatocytes
What is a feature of hepatocytes
A dense cytoplasm
What are the 8 parts of the liver
1) Hepatic vein
2) Sinusoid
3) Bile Canaliculus
4) Bile duct
5) Hepatic portal vein
6) Hepatic artery
7) Hepatocytes (liver cell)
8) Kupffer cell
What part of the liver is an intra-lobular vessel
Hepatic vein
What parts of the liver are inter-lobular vessels
1) Bile duct
2) Hepatic portal vein
3) Hepatic artery
What are sinusoids
Channels that carry blood between rows of cells where blood from the hepatic vein and hepatic artery mixes
What are the kupffer cells
Macrophages that break down old red blood cells and release bilirubin
What function do bile canaliculus have
Carries bile which the hepatocytes secretes and drains into the bile ductules
What is the average mass of protein an adult needs per day
40-60g
What is the problem with consuming too much protein
Too much protein means that your body cannot store the amino acids (in the protein) because of the toxicity of their amine group
How does the liver solve the problem of not being able to store amino acids
By converting the amino-acids to urea to be excreted in a two step process
What is the overall equation of the conversion of amino acids
Amino acids ——> Ammonia ——> Urea
^ ^
| |
Deamination Urea formation
Explain the first step of the conversion of amino-acids
1) Deamination
Amino acid + oxygen ——> Keto-acid + Ammonia
^
|
Enters respiration
Why are amino acids not directly excreted
-as they contain a large amount of energy
Why is ammonia still converted and what is it converted to
-as it is still highly soluble and very toxic
-is converted to urea which is less toxic
What is the cycle that ammonia is converted in called
The Ornithine cycle
Describe the second step of the two step process in the conversion of amino acid
urea formation:
1) CO2 + NH3 is added to ornithine which produces H2O and citrulline
2) NH3 is added to citrulline which produces H2O and arginine
3) H2O is added to arginine which produces urea
4) this urea goes to the kidney to be excreted
What substances does the liver detoxify
1) drugs consumed
2) hydrogen peroxide (which is produced in cells)
3) alcohol
How does the liver detoxify drugs
-A group of enzymes Cytochrome P450 break down drugs such as cocaine as well as medical drugs
How does the liver detoxify Hydrogen peroxide (produced in cells)
-catalase (enzyme) converts hydrogen peroxide to water and oxygen to prevent the build up of toxic molecules in cells
Why does the liver have to detoxify alcohol
-as it contains ethanol ( a drug) that suppresses nerve activity
When detoxified how can ethanol be used
-To produce energy for respiration
Explain how alcohol is detoxified
REDOX reaction:
Ethanol= oxidised
NAD= reduced
1) ethanol is oxidised to form ethanal, using the enzyme ethanol dehydrogenase and NAD is reduced in the process (using the H+ ion form ethanol)
2) ethanal is oxidised to form ethanoic acid (ethanoate) (acetate), using the enzymes ethanal dehydrogenase and NAD is reduced in the process (using the H+ ion from the ethanal )
What is the detoxification of alcohol called
Redox reaction
-ethanol is oxidised
-NAD is reduced
What is NAD also needed for
To oxidise and break down fatty acids to use in respiration
What is the problem with drinking too much alcohol and what could it cause
-the liver has to detoxify too much alcohol so it uses all its stored NAD so there is not enough NAD left to break down the fatty acids
- the fatty acids will then be converted back to lipids and gets stored in the hepatocytes causing an enlarged fatty liver and possible hepatitis/cirrhosis
What does intra-lobular mean
Within a lobule
What does inter-lobular mean
Between lobules
In what organelle does the ornithine cycle take place in
Mitochondria
