1. MOUTH STOMACH Lingual Lipase FFA + DAGs (miniscule amounts)
Lipids: Triacylglycerols
Cholesterol esters
Phospholipids
MOUTH
FFA + DAGs
(small amounts)
Lingual Lipase
("acid-stable") 1b
Triacylglycerols
STOMACH
STEP 1: Digestion in the Mouth and Stomach
Courtesy of Dr. Marc Tischler

2. SMALL INTESTINE duodenum/jejunum EXOCRINE PANCREAS CCK-PZ from stomach
stimulates
secretion
FFA
from stomach
trypsinogen,
procolipase,
lipase, esterase,
HCO3-, proPLA2
Endocrine cell
Cholecystokin-pancreozymin (CCK-PZ)
via bloodstream
Trypsinogen
Pancreatic
lipase
esterase
Procolipase
Pancreatic ProPLA2
Bile Salt
storage
SMALL INTESTINE
duodenum/jejunum
Bile Acid
Synthesis
Conjuga-
tion LIVER
GALL BLADDER
CCK-PZ causes contraction
STEP 2: Enzymatic Digestion in the Duodenum/Jejunum –
secretion of zymogens/bile salts
Courtesy of Dr. Marc Tischler

3. Enterohepatic circulation of bile acids
SMALL INTESTINE
duodenum/jejunum
LIVER
Enterohepatic circulation of bile acids 3b
Portal vein
Mixed Micelles 4
FFA,
2MG
cholesterol
lysolecithin
vitamin A
Short/medium
chain FFA
Released
bile acids 3b
Reabsorbed by ileum
Capillaries
STEP 3b: Bile Acid Recycling
STEP 4: Lipid Absorption
Courtesy of Dr. Marc Tischler

4. To lacteals and thoracic duct (lymphatic system)
SMALL INTESTINE
duodenum/jejunum 6b
To lacteals and thoracic duct (lymphatic system) 6a
B48
Coating with apolipoprotein
(with TTP)
Chylomicron
vitamins
D, E, K
Triacylglycerol transfer protein
Triacyl-
glycerol
Cholesterol
ester
Phospholipid
FFA,
2MG
cholesterol
lysolecithin
vitamin A
reesterification 5
ACAT
Acyl CoA: cholesterol acyl transferase
STEP 5: Re-esterification
STEP 6: Chylomicron Assembly
and Export
Courtesy of Dr. Marc Tischler

5. chylomicron interacts with lipoprotein lipase removing FFA
Lymph system:
Chylomicrons to capillaries via lymph
INTEST
INE
Nascent chylo-microns acquire apo CII (C) and E (E) from HDL
non-hepatic tissues
C E
C E
C E
C E
ApoB48 aids with chylo-micron assembly
LIVER
Chylomicrons carry dietary fatty acids to tissues and the remnants take cholesterol to the liver

6. chylomicron interacts with lipoprotein lipase removing FFA
Lymph system:
INTEST
INE
C E
chylomicron acquires apo CII (C) and E (E) from HDL
non-hepatic tissues
C E
C E C E
chylomicron remnants lose CII to HDL C E
ApoB48 E
Liver: apo E receptor takes up remnants to deliver cholesterol
LIVER
Chylomicrons carry dietary fatty acids to tissues and the remnants take cholesterol to the liver
Courtesy of Dr. Marc Tischler