Gastrointestinal Tract Lipid Digestion and Absorption
• COMPOSITION OF FAT ENTERING THE GI TRACT:
DIETARY (80-100G/DAY) ENDOGENOUS (BILE)
90% triacylglycerol (TAG) 10-15g phospholipid
5% phospholipids 1-2g cholesterol ester
0.5% cholesterol ester 6g intestinal cells
10g dead cells
• Minor digestion in the mouth and stomach
1. LIPID DIGESTION IS INITIATED IN THE MOUTH, LINGUAL LIPASE
• HYDROLYSIS of DIETARY FATS (TAG) with short and medium chain fatty acid (e.g. Milk, fat); some of
free fatty acid released
• It is not important nutritionally in humans
• Perception of fat taste
• LIPASE = a globular protein
• Unable to penetrate surface area of lipid particles
• SALIVARY LIPASE = active at low pH
• Minor lipid digestion
2. IN THE STOMACH, GASTRIC LIPASE (FUNDIC CHIEF CELL; limited action of TG hydrolysis
• GASTRIC MOTILITY = plays a crucial role in lipid digestion
• It is in the first stage in the process of emulsification (increase in surface area of lipids) for digestion
• EMULSIFICATION = the major process in fat digestion, breaking large droplets into smaller ones
• It BEGINS by AGITATION in the STOMACH to MIX the FAT with the PRODUCTS of DIGESTION
• Main dietary fat digestion and absorption occurs in the small intestine - Emulsification and digestion
1. Emulsification by bile salts and phospholipids
2. Breakdown the course emulsion into smaller and more stable particles
Integration of Physiological Systems Page 1
• COMPOSITION OF FAT ENTERING THE GI TRACT:
DIETARY (80-100G/DAY) ENDOGENOUS (BILE)
90% triacylglycerol (TAG) 10-15g phospholipid
5% phospholipids 1-2g cholesterol ester
0.5% cholesterol ester 6g intestinal cells
10g dead cells
• Minor digestion in the mouth and stomach
1. LIPID DIGESTION IS INITIATED IN THE MOUTH, LINGUAL LIPASE
• HYDROLYSIS of DIETARY FATS (TAG) with short and medium chain fatty acid (e.g. Milk, fat); some of
free fatty acid released
• It is not important nutritionally in humans
• Perception of fat taste
• LIPASE = a globular protein
• Unable to penetrate surface area of lipid particles
• SALIVARY LIPASE = active at low pH
• Minor lipid digestion
2. IN THE STOMACH, GASTRIC LIPASE (FUNDIC CHIEF CELL; limited action of TG hydrolysis
• GASTRIC MOTILITY = plays a crucial role in lipid digestion
• It is in the first stage in the process of emulsification (increase in surface area of lipids) for digestion
• EMULSIFICATION = the major process in fat digestion, breaking large droplets into smaller ones
• It BEGINS by AGITATION in the STOMACH to MIX the FAT with the PRODUCTS of DIGESTION
• Main dietary fat digestion and absorption occurs in the small intestine - Emulsification and digestion
1. Emulsification by bile salts and phospholipids
2. Breakdown the course emulsion into smaller and more stable particles
Integration of Physiological Systems Page 1
