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What happens to bilirubin after it is formed from hemoglobin breakdown?
Bilirubin is transported in plasma bound to albumin for solubility, then de-conjugated in the liver and re-conjugated with glucuronic acid for bile transport.
What is deamination and what product does it generate from L-glutamate?
Deamination is the process where the amino group is liberated from L-glutamate, resulting in the production of alpha-ketoglutarate and ammonia.
What is the Ornithine cycle responsible for?
The Ornithine cycle is responsible for removing ammonia, a toxic byproduct of deamination, by converting it into urea in the liver.
What role does carbamyl phosphate synthetase play in the urea cycle?
Carbamyl phosphate synthetase binds ammonia with carbon dioxide to produce carbamyl phosphate, which enters the Ornithine cycle.
How is urea produced in the Ornithine cycle?
Carbamyl phosphate, bound to L-ornithine, undergoes several steps in the Ornithine cycle, culminating in the production of urea.
What happens to urea after it is produced?
Urea is excreted by the kidneys, but some may diffuse back into the intestine where it can be converted to ammonia by enteric bacteria.
What are xenobiotics and how does the liver deal with them?
Xenobiotics are substances not normally found in the body, like certain drugs, and the liver detoxifies them through a process called biotransformation.
What are the two main steps of biotransformation in the liver?
The first step reduces the toxicity of a molecule, and the second step increases its solubility for removal from the body.
What occurs during the process of biotransformation?
Biotransformation involves modifying the chemical structure of substances to inactivate and facilitate their excretion.
How does the liver influence hormone metabolism?
The liver inactivates and excretes hormones such as steroids, insulin, and glucagon, through processes like proteolysis and deamination.
What methods can be used in the first step of detoxifying a molecule?
Methods include oxidation, reduction, hydrolysis, or acetylation, which help in reducing the molecule's toxicity.
Where is bilirubin formed in the body?
In the spleen during the breakdown of red blood cells.
What transports bilirubin in the plasma?
Bilirubin is conjugated to albumin for solubility.
What happens to bilirubin once it reaches the liver?
It is de-conjugated from albumin and conjugated to glucuronic acid.
How does bilirubin get its yellow color?
Bilirubin is yellowish, resulting from the reduction of greenish bilirubin.
What is urobilinogen?
A colorless substance formed from bilirubin by intestinal bacteria.
How is urobilinogen excreted?
It can enter circulation and be excreted via the kidneys or return to the liver.
What causes the brown color of feces?
Stercobilin, formed from the reduction of urobilinogen.
What is the consequence of excessive bilirubin in the blood?
It causes jaundice, leading to yellow discoloration of the skin and eyes.
What is hemolytic jaundice?
Jaundice resulting from excessive destruction of red blood cells.
How is neonatal jaundice typically treated?
With UV light to facilitate the isomerization of bilirubin.
What stimulates the production of cholecystokinin?
The presence of fatty acids, amino acids, and chyme in the digestive system.
What effect does secretin have?
It stimulates bile production in the liver.
What is the Ornithine cycle responsible for?
The conversion of toxic ammonia into urea for excretion.
What role do transaminases play in amino acid metabolism?
They catalyze the transfer of amino groups during transamination.
What does deamination produce from L-glutamate?
Alpha-ketoglutarate and ammonia.
What is the fate of ammonia produced from amino acid catabolism?
It is converted into urea in the liver to be excreted.
What is the function of albumin in relation to bilirubin?
It binds to bilirubin to increase its solubility in plasma.
What happens to bilirubin during the breakdown of hemoglobin?
It gets converted to heme and subsequently to bilirubin.
