SS1. Detoxification by the liver Flashcards
When does deamination of AA occur?
during gluconeogenesis.
What product is formed during AA deamination?
formation of ammonia, toxic and strong base. Is converted to urea which can be secreted via the kidneys.
What are ammonium and bicarbonate ions transformed into?
carbamyl phosphate, by carbamyl phosphate synthetase.
What does carbamyl phosphate combine to, and what is the function of this product?
Combines with ortinine, forms cirruline.
Cirruline is converted to arginosuccinate & arginine. This gives rise to urea and onithine.
What happens to ornithine?
It re-enters the urea cycle to create more urea.
What are Xenobiotics?
Substances that aren’t normally present in the body. It enters via drugs, constituents of plants, food contamination such as plasticizers and dioxin.
What are the two phases of neutralising xenobiotics via biotransformation/detoxification?
Phase I and phase II
What is the 1st phase of the detoxification of xenobiotics?
Foreign molecule is modified by oxidation, reduction or hydrolysis
What is the 2nd phase of the detoxification of xenobiotics?
Modified molecule conjugates to inactivate it and make it easier to excrete. e.g, glucuronic acid, sulphate, acetate.
What is an example of xenobiotics?
Aspririn. It’s hydrolysed to salicylic acid, which conjugates to glucuronic acid to form salicylglucuronide.
Does phase I always result in reduction/loss of biological activity of xenobiotics?
No, it sometimes increases toxicity.
How are hormones such as steroids inactivated and excreted?
They’re oxidized by cytochrome P450 enzymes to make them more H2O soluble and make them inactive.
