Metabolic functions of liver Flashcards
Describe the location of zones 1, 2, 3 in the acinus
Zone 1: closer to afferent arteriole (for functions that need the most oxygen)
Zone 2: ill-define intermediate area
Zone 3: Closer to the central hepatic veins
What kind of processes occur in zone 1 of the acinus?
Oxidative functions
e.g. urea synthesis, gluconeogenesis, cholesterol synthesis, production and excretion of bile, oxidative energy metabolism (beta oxidation of fatty acids, respiratory chain, citric acid cycle)
What kind of processes occur in zone 3 of the acinus?
Non-aerobic functions:
Xenobiotic metabolism
Glycolysis
Glutamine synthesis (AA used to make proteins)
How and WHERE are carbohydrates/glucose stored in the body?
As glycogen in liver
What is glycogenolysis?
Breakdown of glycogen into glucose
Define gluconeogenesis
synthesis of glucose from other sources, e.g. lactate, pyruvate, glycerol and alanine
What process occurs to allow fructose and galactose to enter glycolysis
They are both converted into glucose phosphatases
What is glucose used as an energy substrate for in respiration?
glycolysis, citric acid cycle, synthesis of FA and TG
What is the role of the liver in lipid metabolism?
Actively involved in beta oxidation: breakdown of short chain fatty acids into acetyl co-A
Synthesis of Fatty Acids TG, Cholesterol, phospholipids and lipoproteins
What is the role of the liver in protein metabolism?
Synthesis of non-essential amino acids
Produces plasma proteins - type of glycoprotein (e.g. albumin)
Produces glycoproteins
Glycation (glycosylation) of liver
Deamination and transamination of amino acids
Production and Removal of ammonia from the body
Nitrogen conversion into urea and urea excretion
Why is biotransformation in the liver needed?
Needed to metabolise xenobiotics (drugs) before they are excreted
Describe phase 1 of drug metabolism (biotransformation)
Phase 1: occurs in the smooth ER, involves chemical reactions such as oxidation, hydrolysis, reduction. These reactions are mediated by cytochrome P450.
Describe phase 2 of drug metabolism (biotransformation)
Phase 2: conjugation occurs (attachment of ionised groups to the drug) which makes the drug soluble enough to be excreted in urine.
What is the principal site of drug metabolism in a cell?
Smooth endoplasmic reticulum
How much bile is produced per day and how much is excreted?
3L produced/day
1L excreted/day
