Physio 8: SI, Absorption Flashcards
What 3 sugars are absorbed in small intestine?
glucose, fructose, galactose
What are brush border enzymes? Name 3.
Enzymes anchored to enterocyte cell membrane. Sucrase, lactase, maltase.
What transporter cotransports sugars with Na+ on the luminal side?
SGLT 1
What transporter transports fructose into the cell?
GLUT 5
What transporter gets sugars into blood?
GLUT 2
How does insulin regulate GLUT2?
Binds to enterocyte receptor and traffics GLUT 2 transporters away from membrane to slow absorption.
What sugar is a dimer of glucose?
Trehalase
How are proteins absorbed and digested in SI?
- AA and oligopeptides absorbed via Na and H+ transporters
2. Intracellular peptidases and blood peptidases break down peptides further
Are transporters more efficient with di and tri-peptides or single AA’s?
Di and tri peptides
What is Hartnup’s disease?
Impaired absorption of AA’s like histidine, tryp, phenylalanine
What is cystinuria? Why don’t patients develop lysine deficiency?
Disorder of SI - defect in proximal tubule’s reabsorption of filtered cysteine and basic AA’s
No lysine deficiency b/c get essential lysine from diet through PEPT1 transporter
How are lipids digested and absorbed in SI?
- Gastric lipolysis through gastric lipase (from Chief cells)
- Intestinal lipolysis - bile acids emulsify, pancreatic enzymes digest
- Digested products (cholesterol, MAGs, lysolethicin, FFAs) absorbed in lumen
- Fats repackaged into chylomicrons and sent to lymphatic system
What type of lipases breaks down triglycerides? What are the end products?
Lingual, gastric, and pancreatic lipases
Products: Monoglyceride, 2 FAs
What type of lipase breaks down cholesterol ester? End products?
Cholesterol ester hydrolase
Cholesterol and FA
What type of lipase breaks down phospholipids? End products?
Phospholipase A - lysolecithin and FA
