Metabolic Functions of the Liver Flashcards
What are the Phase I reactions in the metabolism of drugs in the liver?
They catalyze the oxidation of these substances, usually adding -OH or -COOH to them.
What enzyme catalyzes the Phase I reactions?
NADPH-cytochrome p450 reductase
What are the Phase II reactions of drug metabolism?
The products from the Phase I reactions are conjugated to make them more hydrophilic and thus, soluble.
What plasma proteins does the liver make and what is their role?
The liver makes most of the plasma protein and their role is varied -> major functions are in blood clotting and iron metabolism.
How is vitamin A transported to the liver?
Transported in chylomicrons to the liver as an ester of long FAs
How does the liver mobilize vitamin A as blood levels fall?
Hydrolyzes the retinyl ester and the retinol binds the retinol-binding protein which is then secreted into the blood
How is vitamin D3 transported to the liver?
Transported in chylomicrons to the liver in a non-esterified form
Where are the major vitamin D stores?
Adipose and skeletal muscle
Why is vitamin K important in the liver?
It is required for the synthesis of prothrombin
What is iron stored as in the liver?
Ferritin
What is the importance of copper in the liver?
The liver takes up and stores copper as well as secretes it in bile.
