4.1 Digestive System Nutrient Digestion Flashcards
Complex carbohydrates must be ________ digested into ________ before absorption into blood
Enzymatically
Monomers (glucose, fructose)
What chemicals are involved in carbohydrate absorption in the small intestine?
Pancreatic amylase, brush border enzymes
Brush border enzymes…
Complete the breakdown of starch to individual glucose molecules
First step of protein digestion in small intestine
Proteolytic enzymes are released from pancreas
Enteropeptidase activates ________ to _______, which then activates other proteolytic enzymes
Trypsinogen
Trypsin
Activated pancreatic proteolytic enzymes break proteins into ______ and ______
Peptides and amino acids
Brush border peptidases break peptides into…
Single amino acids to be absorbed through epithelial cell into blood
Protease proenzymes are activated by….
Cleavage
Bile salts released from the liver and gall bladder emulsify lipid droplets to form….
Micelles
_________ functions within micelles to digest each ________ into a _________ and ____________
Pancreatic lipase
Triglyceride
Monoglyceride
Two free fatty acids
Monoglycerides and free fatty acids enter an _________ _____, while bile says remain in the intestinal lumen to be reabsorbed and recycled.
Epithelial cell
What happens in the epithelial cells during lipid digestion?
Triglyceride molecules are reassembled… then wrapped / packaged and then exocytosed
In the epithelial cells, lipids are wrapped with protein to form a…..
Chylomicron
What happens after chylomicrons are formed?
They are packaged within secretory vesicles and exocytosed grin the cells and absorbed into lacteals
How are lipids absorbed into the blood?
Lymphatic lacteals carry chylomicrons back to blood, circle without going directly to liver
How are packaged lipids absorbed differently than all other nutrients?
Virtually all other blood borne nutrients pass first through the liver before entering systemic circulation
Chylomicrons are taken up by…
Fat cells in periphery
VLDL
Very bad, similar to chylomicron but made by liver
LDL
Released from fat cell (fat keeps most of the triglycerides).. Delivers triglyceride and cholesterol to tissues
HDL
Good, released by tissues and returned to liver (moves cholesterol back to gut / bile)
NET REDUCTION IN CHOLESTEROL
Capillary endothelium captures LDLs and HDLs by…
Receptor mediated endocytosis