18 Questions
What is the role of cytochrome P450 enzymes in drug metabolism?
They enzymatically oxidise compounds to make them more polar and soluble.
Give an example of a drug that undergoes glucuronidation in the liver.
Zidovudine
What happens when acetaminophen is metabolized in excess in the liver?
It is oxidised to N-acetyl benzoquinoneimine (NABQI) by cytochrome P450.
How does N-acetyl-L-cysteine (NAC) act in cases of acetaminophen poisoning?
It replenishes glutathione by metabolizing to L-cysteine.
Why is NABQI toxic to cells in cases of acetaminophen overdose?
Due to its oxidant properties.
In drug metabolism, how are polar drug metabolites excreted from the body?
By the kidneys.
What are the key pathways of carbohydrate metabolism in the liver?
Gluconeogenesis, glycogenolysis, and glycogenesis
Describe the process by which the liver generates fat from carbohydrates.
Fatty acid synthesis
What is the primary storage medium of glucose in the liver?
Glycogen
What is the role of the liver in the synthesis of very low density lipoproteins (VLDLs) and low density lipoproteins (LDLs)?
Synthesis of VLDLs and LDLs
How does the liver contribute to protein and amino acid metabolism?
Gluconeogenesis from amino acids, transamination reactions, synthesis of serum proteins
What is the liver's involvement in the synthesis of heme?
Synthesis of heme
What is the name of the cycle in which alanine is transported to the liver, converted to pyruvate, and then can participate in oxidative phosphorylation or be converted to glucose?
Inter-organ glucose alanine cycle
Which amino acid acts as a central molecule in transamination reactions and is an intermediary in the urea cycle?
Glutamate
What is the fate of the NH3 group released from glutamate in transamination reactions?
Enters the urea cycle and is excreted by the kidneys
What are glucogenic amino acids and how are they metabolized?
Amino acids that can be catabolized to form a citric acid cycle intermediate
Define ketogenic amino acids and explain their catabolic pathway.
Amino acids that are catabolized to form acetoacetate or a precursor
How are the intermediates of the citric acid cycle continuously replenished?
Through anaplerotic reactions
Test your knowledge on cytochrome P450 enzymes and drug metabolism processes, including phase I reactions like oxidation and phase II reactions like glucuronidation and sulfation. Learn about the role of these enzymes in making compounds more polar and soluble for elimination.
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