18 Questions
Where does absorption of ascorbic acid (Vitamin C) primarily occur?
Entire small intestine
Which vitamin is primarily absorbed through receptor-mediated endocytosis in the distal ileum?
Vitamin B12
How is niacin (Vitamin B3) primarily absorbed in the small intestine?
Carrier-mediated
What is the mechanism of absorption for biotin (Vitamin B7) in the intestines?
Carrier-mediated
In which part of the GI tract do muscle cells act as a conveyor belt to move contents in the proper direction?
Small intestine
What happens to iron absorption when less iron binds to ferritin?
Iron absorption increases
Which region of the intestine is the most permeable in terms of paracellular permeability?
Duodenum
What is the main reason for the flow of fluids mainly from blood to lumen in the small intestine?
High osmotic pressure in the lumen
Which lipoprotein is formed as a result of lipid digestion and reprocessing within enterocytes?
Chylomicrons
What role does bile play in the digestion of dietary fats?
Emulsifying dietary fats
In which layer do lipids cross before entering the cytosol during the process of lipid absorption?
Unstirred layer
Which ion is more abundantly transported in distal regions of the intestine?
Sodium (Na+)
What is the primary role of lipase and colipase in lipid digestion?
To break down lipids into fatty acids and monoglycerides
What is the function of cholesterol esterase in lipid digestion?
To break down cholesterol esters into cholesterol and fatty acids
What is the primary function of micelles in lipid absorption?
To transport lipids across the unstirred layer and into the intestinal epithelial cells
What is the role of fatty acid binding proteins (FABP) in the cytosolic reprocessing of lipids?
To bind and transport fatty acids to the smooth endoplasmic reticulum for re-esterification
What is the final step in the absorption of lipids across the intestinal epithelium?
The exocytosis of chylomicrons across the basolateral membrane
What is the role of phospholipase A-2 in lipid digestion?
To produce fatty acids and lyosphosphatides from phospholipids
Test your knowledge on lipid digestion and absorption processes, including the roles of lipase, colipase, cholesterol esterase, and phospholipase A-2. Explore how products of lipid digestion form micelles with bile acids for absorption.
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