ANSC 330 Lecture 9: ANSC 330 Lecture 9
ANSC 330
Lecture 9
❖ Lipids
➢ Non-ruminants
▪ Emulsification
▪ Digestion
▪ Absorption and transport
➢ Ruminants
▪ Digestion
▪ Emulsification
▪ Further digestion
▪ Absorption and transport
❖ Preparation for Digestion (non-ruminants)
➢ Lipids are hydrophobic
▪ When they mix with aqueous digesta in the stomach, they form large lipid globules that are
insoluble in water
• Have relatively small surface area compared to the large volume
▪ Digestive enzymes have little access to lipids when they exist in this large globule form
▪ Have to be emulsified to increase the surface area per unit of volume for sufficient
enzymatic hydrolysis to occur
❖ Emulsification
➢ Bile salts (synthesized in the liver) emulsify the large lipid globules in the duodenum of the SI
➢ Forms smaller lipids droplets, which are further emulsified
▪ Eventually forms a structure known as a micelle
▪ Relatively high surface area for a small volume
❖ Fat Digestion (non-ruminants)
➢ Lipolysis is initiated in the duodenum of the small intestine
▪ Pancreatic lipase
• Adheres to the surface of the small lipid droplet
Facilitated by the enzyme collapse
• Hydrolyzes ester bonds at the 1 and 3 positions of the triglyceride
Triglyceride + lipase = 2 free fatty acids and an intact monoglyceride
➢ Lipolysis results in the formation of micelles
▪ Micelles may contain
• Bile salts
• Free fatty acids
• Monoglycerides
• Cholesterol
• Phospholipids
• Fat-soluble vitamins
▪ Micelles are water soluble
❖ Fat absorption (non-ruminants)
➢ Movement into the enterocyte
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Non-ruminants: emulsification, digestion, absorption and transport. Ruminants: digestion, emulsification, further digestion, absorption and transport. Bile salts (synthesized in the liver) emulsify the large lipid globules in the duodenum of the si. Forms smaller lipids droplets, which are further emulsified: eventually forms a structure known as a micelle, relatively high surface area for a small volume. Lipolysis is initiated in the duodenum of the small intestine: pancreatic lipase, adheres to the surface of the small lipid droplet. Facilitated by the enzyme collapse: hydrolyzes ester bonds at the 1 and 3 positions of the triglyceride. Triglyceride + lipase = 2 free fatty acids and an intact monoglyceride. Lipolysis results in the formation of micelles: micelles may contain, bile salts, free fatty acids, monoglycerides, cholesterol, phospholipids, fat-soluble vitamins, micelles are water soluble. Movement into the enterocyte: micelles move to the brush border membrane, micelle dissociates, contents diffuse into the enterocyte via concentration-dependent gradient, triglycerides will not move across the membrane intact.
