19. Role of the liver in carbohydrate, fat, and protein metabolism Flashcards
What processes take place in Zone 1 of an acinus of the liver?
Closer to afferent arteriole, so: Respiratory chain Citric acid cycle Fatty acid oxidation Gluconeogenesis Urea synthesis Bile production and excretion Cholesterol synthesis Amino acid utililisation
What processes take place in Zone 3 of an acinus of the liver?
Glycolysis Xenobiotic metabolism Glutamine synthesis Ketogenesis Lipogenesis
What 4 roles does the liver play in carbohydrate metabolism?
- Storage of glycogen and glycogenolysis
- Gluconeogenesis
- Uses glucose as an energy substrate (glycolysis, citric acid cycle, synthesis of fatty acids)
- Conversion of fructose and galactose into glucose phosphates
How are lipids metabolised by the liver?
By mitochondrial beta-oxidation of short chain fatty acids
What can the liver produce via lipid metabolism and what are the functions of some of these?
Fatty acids Phospholipids - used in cell membranes Cholesterol - in steroid hormones and cell membranes Triglycerides (glycerol + fatty acids) Lipoprotiens - Carriers of cholesterol
What are the roles of the liver in protein metabolism?
Synthesises most circulating proteins e.g. albumin, glycoproteins
Glycation of proteins
What is the significance of protein synthesis by the liver?
Level of circulating proteins can determine the level of hepatic synthetic function
What is the role of the liver in the metabolism of amino acids and urea?
Nitrogen is converted into urea in the liver and excreted by the kidneys
Clearance of ammonia
What produced ammonia and where is it produced?
Urease+ gut flora produce ammonia in the intestines alongside the production of other toxins
Why is it important that ammonia is cleared from the body?
Low levels of ammonia allow for normal brain activity
