Class 3B. Digestion and Absorption
Digestion and Absorption of Proteins
Proteases
Peptidases
Digestion and Absorption of Vitamins and Metal ions
Digestion and Absorption of Carbohydrates
Digestion and Absorption of Lipids
Bile Salts
Physicochemical Properties
Function
Emulsification of lipids in food
Synthesis
Precursor
Re-absorption
also known as: Enterohepatic Circulation
Hydrolysis
Triacylglycerol = Triglyceride
Enzyme: lipase
Colipase
Phospholipids
Enzyme: phospholipases
Cholesteryl Ester
Enzyme: esterases
Absorption
Post-absorptive transport
polysaccharides
disaccharides
starch
lactose
sucrose
maltose
organs/body parts for digestion
mouth (saliva)
stomach
liver
pancreas
small intestine
colon
disaccharididase
peptidase
amylase
saliva
small intestine
maltase
sucrase
small intestine
lactase
small intestine
small intestine
polar face AND non-polar face
cholesterol - bile acids
stabilize mixed micelles
amphiphilic
saliva
pancreas
produces
lipase
amylase
amylase
lipase
bile salts
pepsin
protease
chylomicrons
simple diffusion
Because of both limited solubility and detergent properties of free fatty acids
free fatty acids need to be re-esterified to less polar products for transport in the form of lipoprotein aggregates
free fatty acids released from adipocytes are transported in plasma bound to serum albumin,
the high concentrations of free fatty acids present after a meal would overwhelm the albumin transport system.
composition
triglyceride (84%)
other lipids and proteins
cholesterol
cholesteryl ester
phospholipids
apolipoproteins
absorbed towards the end of ileum of small intestine
carried in portal blood, bound to albumin
added to bile again by liver and secreted again through gallbladder
pepsin
site-specific cleavage
trypsin
chymotrypsin
elastase
activated from pepsinogen by HCl
activated from trypsinogen
activated from chymotrypsinogen
activated from proelastase
aminopeptidase
carboxypeptidase
fat soluble vitamins
minerals
Regulation of digestion
gastrin
cholecystokinin
secretin
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