Carbs 2 Flashcards
Composition of ions in the intestine?
- Low Na in the cell
- High K in the cell
How is glucose absorbed by microvilli?
- attaches to Na in intestine
- Na constantly pumped across membrane
What happens to glucose after absorption by microvilli?
- Actively transported by GLUT2 transporters into the blood
- Travels to liver through hepatic portal vein
Why does glucose get constantly moved in and out of the cell?
- Na conc is kept low as possible in the cell
- This means glucose is still pumped in regardless of [bloodGLC]
What are cellulose and hemicellulose used for in the body?
- Increasing faecal bulk.
- Decreases time taken for waste to move through the gut.
How can disaccharide deficiencies come about?
- Genetic
- Intestinal infection
- Inflammation of epithelium
- Drugs altering pH
How are disaccharide deficiencies diagnosed?
Testing for enzyme deficiencies
What happens to undigested lactose in the gut?
Broken down by bacteria to release gas
Why does lactose cause diarrhoea?
Is osmotically active, will draw water into the intestine.
What happens to glucose when it reaches the liver from the gut?
Converted to G-6-P
Why is glucose converted to G-6-P?
It won’t leave the cell in the hepatocytes as GLUT transporters don’t recognise it. Can’t diffuse.
What enzymes do convert glucose to G-6-P in the liver and tissue respectfully?
- Glucokinase in the liver
- Hexokinase in the tissue
If blood [glucose] is normal, does the liver take it all up?
No - some is taken up by tissues (hexokinase)
What does the liver do when blood [glc] is high?
Takes up all of it and phosphorylates it very quickly
After Glc is converted to G-6-P in the tissue, what can it be used for?
- Can be used for glycolysis (substrate level phosphorylation)
- To produce pentoses
- Stored as glycogen
