Lipid Digestion Muhammad Mustansar FJMC LAHORE
•
9 likes•2,759 views
Lipids are composed of carbon, hydrogen, and oxygen and include fats, oils, phospholipids, and steroids. They are not water soluble and are digested in the mouth, stomach, and small intestine by lingual, gastric, and pancreatic lipases. In the small intestine, bile salts emulsify lipids into small droplets for further digestion by pancreatic lipase into fatty acids, monoglycerides, and glycerol, which are then absorbed. Undigested fats in the stool is known as steatorrhea.
More Related Content
What's hot
What's hot (20)
Viewers also liked
Viewers also liked (20)
Similar to Lipid Digestion Muhammad Mustansar FJMC LAHORE
Similar to Lipid Digestion Muhammad Mustansar FJMC LAHORE (20)
More from Dr Muhammad Mustansar
More from Dr Muhammad Mustansar (20)
Recently uploaded
Recently uploaded (20)
Lipid Digestion Muhammad Mustansar FJMC LAHORE
- 2. DIGESTION OF LIPIDS DR MUHAMMAD MUSTANSAR
- 4. DEFINITION • Lipids may be regarded as organic substances relatively insoluble in water, soluble in organic solvents i.e. alcohol, ether etc, related to fatty acids and utilized by living cells • Unlike the polysaccharides, proteins and nucleic acids, lipids are not polymers • They are mostly small molecules.
- 5. Lipids Lipids are composed of C, H, O long hydrocarbon chain Diverse group fat fats phospholipids steroids Do not form polymers big molecules made of smaller subunits not a continuing chain
- 6. Most membrane lipids are amphipathic, having a non-polar end and a polar end. Fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end.
- 7. Building Fats Triacylglycerol 3 fatty acids linked to glycerol ester linkage = between OH & COOH
- 9. Saturated fats All C bonded to H No C=C double bonds long, straight chain most animal fats solid at room temp. contributes to cardiovascular disease (atherosclerosis) = plaque deposits
- 10. Digestion of Lipids The major dietary lipids are TRIACYL GLRCEROL CHOLESTEROL PHOSPHOLIPIDS
- 11. DIETARY FAT : - 90% is normally triglycerides. - Cholesterol, Cholesteryl esters, Phospholipids, and Unesterified fatty acids. Average Normal Pakistani Diet: 20-30 gm/day Western Diet: 2 or 3 times of this
- 12. Digestion in Mouth • Very little amount of lipid digestion takes place in mouth because of the presence of Lingual lipase. Lingual lipase action continues in stomach also. • It acts mainly on short chain Tryglycerides.
- 13. Digestion in stomach • Lipids are emulsified by peristaltic movements • Gastric lipase is an important lipid digesting enzyme in stomach. • Around 30% digestion of TAG occurs in stomach
- 14. IN STOMACH • Lingual lipase: - Active at low ph (pH 2.5 – 5) - Short chain TGS. - In milk, butter and ghee. • Gastric lipase: - Up to 30% of TGS
- 15. IN SMALL INTESTINE 1.Emulisification: Dispersion of lipids into small droplets - Bile salts ( detergent action ) Function to transport cholesterol in the digestive system - Peristalsis ( mechanical mixing ) - phospholipids
- 16. Digestion in Intestine Emulsification • Bile Bile Salts Neutralization of acid • Pancreatic Juice – Pancreatic Lipase Co Lipase Cholesterol esterase Phospholipases. All these lipases target primary ester linkage.
- 17. Pancreatic juice: - Pancreatic lipase - Cholesterol estarase Lipolytic enzymes - Phospholipase A2 - Colipase TG particle colipase lipase
- 18. Bile Salts Bile salts are synthesized from cholesterol in the liver - they are stored in the gall bladder and released into the upper small intestine to help break down fats and oils (like soaps) - too much accumulated cholesterol in the gall bladder can lead to gallstones; if a gallstone passes into the bile duct, severe pain results and the gallbladder often has to be removed cholic acid, a bile acid O CH3 CH2 C OH N COO- Na+ CH3 H glycine, an amino acid CH3 HO OH sodium glycocholate, a bile salt
- 19. Structure of a Glycerophospholipid
- 20. Steroids Steroids are lipids containing a steroid nucleus (core structure) The steroid nucleus is a fused ring system consisting of three cyclohexane rings and one cyclopentane ring The rings are designated A, B, C and D Attachment of different groups to the core steroid structure leads to a wide variety of steroid compounds, including cholesterol, bile salts and steroid hormones C D A B
- 21. Physiologically important lipases Lipase Site of action Preferred substrate Product(s) Lingual / acid stable Mouth , stomach TAGS with med chain FFA+DAG lipase FAS Pancreatic lipase + co- Small intestine TAGS with long chain FFA+2MAG lipase FAS Intestinal lipase with Small intestine TAGS with med chain 2FFA+glycerol bile acids FAS Phospholipase A2 + Small intestine PLs with unsat. FA on Unsat FFA lysolecithin bile acids position 2 Lipoprotien lipase Capillary walls TAGs in chylomicron FFA+glycerol insulin (+) or VLDL Hormone sensitive Adipose cell TAG stored in adipose FFA+glycerol lipase cells
- 22. Hydrolysis of lipids • Triglycerides (TG) TG + H2O → Diglyceride + fatty acid (FA) Diglyceride + H2O → Monoglyceride (MG) + FA O O O 2 H2O HO O OH O– O O + 2 O + 2 H+ R OR lipase O R R R
- 23. Absorption of lipids The end products of lipid digestion are Fatty acids Glycerol 2-Monoacylglycerol 1- Mono acylglycerol Cholesterol Lysophonpholipid
- 24. STEATORRHEA Defined as an increase in stool fat excretion of >6% of dietary fat intake due to one or more defects in the digest
- 26. Steatorrhea
- 27. DIGESTION of lipids
Editor's Notes
- Made of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties
- BIG FAT molecule!!
- Mostly animal fats
- Simple chemistry involved in getting the process going. Here is the substrate, triglyceride, two step process to go from triglycerides to monoglycerides. Two steps, in essence, lipase is hydrolyzing two ester bonds, so that here are the two FA that results, this ester linkage is not hydrolyzed by the lipase. An important feature of this is that it converts something that is not absorbable, triglyceride into substances that are absorbable. But also result of this reaction is that it converts something which is very non polar into products that are amphiphilic. Carbonyl groups are partially polar, make them into carboxylic acids, this functional group is much more polar, also oxygen without hydrogen, added hydrogens to them, two hydrogen bond forming groups, hydroxyl groups that are more polar than these bridge oxygens, what is happening in the process is we are generating amphiphilic substances that will be useful for dispersion of products and substrates themselves. In addition cholesterol esters are acted upon by an esterase and phospholipases convert these phospholipids to removing one of the fatty acids, location, arrow is site of action, removing one of the fatty acids forming lysophospholipid, more polar, amphiphilic , contributes to dispersion of the substrates, fats themselves. Digestion producing materials that make digestion go faster. Digestion starts slowly but accelerates as a consequence of product starting to participate as facilitators.