GI physiology: Digestion/absorption 1 Flashcards
What is Trehalose and what enzyme digests it?
Trehalose is 2 glucose molecules in a 1,1 linkage
cleaved by Trehalase
What is lactose and what enzyme metabolizes it?
Lactose is glucose + galactose,
Lactase
What is sucrose and what enzyme digests it?
Sucrose is Glucose and fructose
sucrase
How are glucose and galactose absorbed?
SGLT1 (Na+ cotransporter)
How are glucose and fructose transported across the basolateral membrane?
GLUT 2
How is Fructose absorbed?
GLUT 5
What is the action of pepsin and under what conditions does it function?
Pepsin cleaves protein into aa, di-, and tri-peptides.
Pepsin is activated by low pH and inactivated by high pH
What activates trypsin?
enterokinase
How are amino acids absorbed?
Na+/aa cotransport at luminal membrane
facilitated diffusion at basolateral membrane
How are di- and tri-peptides absorbed?
apical H+ co-transporter
What is the function of cholesterol ester hydrolase?
cleaves cholesterol esters in cholesterol and FAs
What is the function of PLA2?
Cleaves phospholipids into Lysolecithin and FA
What is the function of co-lipase?
Prevents bile salt inactivation of pancreatic lipase.
By which point of the GI tract is most lipid absorbed?
Mid-jejunum
How are pancreatic enzymes for fat digestion activated?
The pancreas secretes HCO3- to increase duodenal pH and activate lipid digesting enzymes
Low pH inactivates said enzymes.
