1. Transportation .. Metabolism
LIPIDS
Digestion .. Absorption ..
Transportation .. Metabolism
Dina Trabzuni

2. Lipids consist of two parts
Glycerol
Fatty Acids
a. Saturated fatty acids
b. Unsaturated fatty acids .Monounsaturated . Polyunsaturated
Figure 3 : Formation of TG

3. Table 1 : Saturated fatty acids

4. Table 2 : Unsaturated fatty acids

5. Lipids are classified as simple or complex
Simple lipid
a. Fatty acids
b. neutral fats (monoglyceride,
diglycerde, and triglyceride)
c. waxes
Complex lipids
a. Phospholipids
b. Glycolipids
c. Lipoproteins
3. Derived lipids
Figure 1 : Triglyceride
Figure 2 : Phosphatidic acid

6. Omega Fatty acid

7. Cis- Trans Fatty acid

8. . Flavor and Satisfaction
Function of Fat
. Energy
. Essential nutrient
. Flavor and Satisfaction
. Adipose Tissue
. Cell membrane Structure
Fat in Food
Fat in Body

9. . Meat Fat (bacon, sausage….)
Food Sources of Fat
. Meat Fat (bacon, sausage….)
. Dairy Fats and products (cream, butter, cheese..)
. Egg yolk
. Monounsaturated , polyunsaturated Fatty acid
. Vegetable oil (safflower, corn, soybean, cottonseed, olive oil)
Animal Fats
Plant Fat

10. . Butter, margarin, salad oils and dressing,shirteninig fat meat
Characteristics Of Food Fat Sources
. Butter, margarin, salad oils and dressing,shirteninig fat meat
. Chees, cream portion of homogenised milk, egg yolk, nuts, seeds, olives…..
Visible Fat
Invisible Fat

11. Digestion of lipids In mouth mechanical digestion Lingual Lipase
In stomach
mechanical digestion
Gastric lipase

12. Bile acid, Pancreatic Lipase, Cholesterol esterase, Phospholipase
In small intestine
Bile acid, Pancreatic Lipase, Cholesterol esterase, Phospholipase
Triglycerides
2 fatty acids + Mono glycerides
3 fatty acids + glycerol
Pancreatic lipase
1 fatty acids + Diglycerides

13. Absorption of lipids
Figure 4 : Absorption of fat.

14. Transportation of lipids
Table 3 Lipids are transported in the plasma as lipoproteins.
Source
Destination
Major lipids
Functions
Chylomicrons
Intestine
Many organs
Triglycerides, other lipids
Deliver lipids of dietary origin to body cell.
VLDLs
Liver
Triglycerides, Cholesterol
Deliver endogenously produced triglycerides to body cells.
LDLs
Intraviscular removal of triglycerides from VLDL
Blood vessels, Liver
Cholesterol
Deliver endogenously produced cholesterol to various organs.
HDLs
Liver and intestine
Liver and steroid-hormone-producing glands
Remove and degrade Cholesterol.

15. . Adipose tissue is the main store of triglyceride in the body.
Lipids Metabolism
. Liver and Adipose tissue play a central role in lipid metabolism.
. Adipose tissue is the main store of triglyceride in the body.
. Lipid metabolism either lipolysis or lipogenesis.
. Fatty acids are both oxidized to acetyl CoA and synthesized from acetyl CoA.

16. Lipolysis
. Complete hydorlysis of triglyceride yeild gelycerol and 3 fatty acids.
. Fatty acids oxidiation take place in the mitochonderia.
. Fatty acids are activated before being catabolized (oxidized).
Fatty acid + ATP + CoA
Acyl CoA + AMP + PPi
acyl CoA
synthetase

17. Long chain fatty acids penetrate the inner -Mitochinderial membrane as carnitine derivatives.
Figure 5 : Role of carnitine in the transport of long chain fatty acids.

18. β - oxidation pathway of fatty acids
. Many tissues are capable of oxidizing fatty acids in the mitochondria by β - oxidation pathway.
. The chain is broken between the α (2) and β (3) carbon atoms.
Figure 6 : Overview of β - oxidation pathway of fatty acids

19. β - oxidation of fatty acids (Figure 7)

20. The products of oxidation of fatty acids
Oxidation of fatty acids produces a large quantity of ATP,
.example : Palmitic acid (C:16 )
7 cycles from 7 NADH + 7 FADH2
(7 x5 = 35 ATP)
7 cycles from 8 Acetyl CoA
(8 x 12 = 96 ATP)
2 ATP for the initial activation
of fatty acid
( – 2 = 129 molecule of ATP)
Figure 8 : acetyl CoA product

21. Oxidation of unsaturated fatty acids occurs by amodified β - oxidation pathway (figure9)

22. Ketone bodies
Ketogenesis occurs when there is a high rate of fatty acid oxidation in the Liver (figure 10).
Acetyl CoA
Acetyl CoA
CoA
Aceto acetyl CoA
CoA
Acetoacetate
β -hydroxy butyrate
Acetone

23. Lipogenesis
. The body is capable of synthesizing fatty acids in the cytoplast of the cell from starter ( acetyl CoA + malonyl CoA).
. Malonyl CoA is formed from Acetyl CoA
Figure 11 : Biosynthesis of Malonyl CoA

24. . Acetyl CoA transfer to the cytoplast across the mitochondrial membrane in the form of citrate
Figure 12 : Conversion the citrate to Oxaloacetate and Acetyl CoA.
. The enzymes involved in fatty acid synthesis are arranged in a complex called the fatty acid synthase system.

25. The steps in the synthesis of fatty acid ( Figure 13)

26. . Cholesterol is not an energy producing nutrient.
. It is an essential structural
component of membrane of the outer layer of plasma lipoprotien.
Bile acids and steriod hormones are formed from cholesterol.
. Cholesteryl ester is a storage form of cholesterol which is found in most tissues.
Figure 14 : Cholesterol

27. Acetyl CoA is the source of all carbon atoms in cholesterol
Acetoacetyl CoA
CoA
Acetyl CoA
Inhibition
β -hydroxy- β- methylglutaryl CoA
HMG-CoA
reductase
Mevalonate
Squalene
Cyclization
Farmesyl pyrophosphate

28. References
Brene, R., Levy, M., Koeppen, B., Stanton, B., (2004) Physiology, Fifth edition. Mosby.
Fox, S., (2004) Human Physiology, Eighth edition. Mc Graw Hill.
Hunt, S., Groff, J., (1997) Advanced Nutrition and Human Metabolism, West Puplishing Company.
Lehninger, A., Nelson, D., Cox, M.,(1993) Principles of Biochemistry, 2nd edtion. Worth Puplishers.
Murray, R., Granner, D., Mayes, P., Rodwell, V., (1996) Haper’s Biochemistry, 24th edition, Prentic-Hall International, Inc.
Seeley, R., Stephens, T., Tate, P., (1992) Anatomy and Physiology,Mosby Yearbook.

29. Thank you