Fatty acids are obtained from the hydrolysis of fats. Fatty acids that occur in natural fats usually contain an even number of carbon atoms (due to synthesis from 2-carbon units) and are straight chain derivatives. The chain may be saturated (containing no double bonds) or unsaturated (containing one or more double bonds).

1. LIPIDS
MISS AMANJOT KAUR SIDHU
MSN (CCN)

2. LIPIDS
•Fatty acids are obtained from the hydrolysis of
fats.
•Fatty acids that occur in natural fats usually
contain an even number of carbon atoms (due
to synthesis from 2-carbon units) and are
straight chain derivatives.
•The chain may be saturated (containing no
double bonds) or unsaturated (containing one or
more double bonds).

3. ISOMERISM
(1) Geometric isomers: They differ in orientation
of the radicals around the axis of the double
bonds.
(a) Cis-form has radicals on the same side of the
bond.
(b) Trans-form has radicals on the opposite side.
This can be illustrated with oleic and elaidic
acids.

4. ISOMERISM

5. ISOMERISM
(2) Positional isomers differ in the position of
the double bonds along the unsaturated fatty
acid chain. Thus, oleic acid could have 15
different positional isomers.

6. CLASSIFICATION OF LIPIDS

7. CLASSIFICATION OF LIPIDS:
BLOOR'S CLASSIFICATION
• Simple Lipids: Simple lipids are esters of fatty acids with
glycerol and other higher alcohol. They are made up of three
fatty acids attached. Oils and fats are the examples of simple
lipids.
• Fats and Oil (Triacylglycerol): These are esters of fatty acids
with glycerol. The difference between fat of oil is only physical.
Oil is a liquid whereas fat is solid at room temperature.
• Waxes: These are esters of fatty acids with alcohol other than
glycerol. These are long chain saturated and unsaturated fatty
acids with long chain alcohol. They are hard when cold but soft
when warm.

8. CLASSIFICATION OF LIPIDS:
BLOOR'S CLASSIFICATION
• Complex or Compound Lipids: Complex or
compound lipids are esters of fatty acids and
alcohol with additional groups. These are
chemicals made up of simple lipids containing
phospholipids, carbohydrates or proteins. Such
compound lipids are known as phospholipids,
glycolipids and lipoproteins respectively.

9. CLASSIFICATION OF LIPIDS:
BLOOR'S CLASSIFICATION
•Derived Lipids: Derived lipids are the
substances produced from simple and
compound lipids through the process of
hydrolysis. These include fatty acids,
glycerol, alcohol, mono and diglycerides and
steroids.

10. CLASSIFICATION OF LIPIDS:
BLOOR'S CLASSIFICATION
•Derived Lipids: Derived lipids are the
substances produced from simple and
compound lipids through the process of
hydrolysis. These include fatty acids,
glycerol, alcohol, mono and diglycerides and
steroids.

11. CLASSIFICATION OF LIPIDS:
BLOOR'S CLASSIFICATION
•Miscellaneous Lipids: Miscellaneous lipids
include a large number of compounds
possessing the characteristics of lipids.
These include steroids, terpenoids,
carotenoids, fatty acids, etc.

12. FUNCTIONS OF LIPIDS
• Storage form of energy (triglycerides).
• Structural components of biomembranes.
• Metabolic regulators (steroid hormones)
• Act as surfactants, detergents and emulsifying agents (amphipathic
lipids).
• Act as electric insulators in neurons.
• Provide insulation against changes in external temperature
(subcutaneous fat).
• Give shape and contour to the body.
• Protect internal organs
• Help in absorption of fat soluble vitamins (A, D, E and K)

13. CLASSIFICATION OF FATTY ACIDS
1. Depending on the nature of hydrocarbon
chain
2. Depending on total number of carbon
atoms
3. Depending on the length of hydrocarbon
chain

14. Depending on the nature of
hydrocarbon chain
1. SATURATED FATTY ACIDS: Their general
formula is Cn H2n+1 COOH. Lower fatty
acids have 10 or less carbon atoms, e.g.
acetic acid, butyric acid. Higher fatty acids
have more than 10 fatty acids, e.g., palmitic
acid, stearic acid.

15. Depending on the nature of
hydrocarbon chain
2. UNSATURATED FATTY ACIDS: They can be
classified further according to degree of
unsaturation:
1. Monounsaturated FA (MUFA) contain one
double bond (mono-ethenoid). There general
formula is CnH2-1COOH, e.g., oleic acid
(C17H33COOH) is found in nearly all fats.

16. Depending on the nature of
hydrocarbon chain
2. Polyunsaturated FA (PUFA) contain two or more
double bonds (polyethenoid), generally after every
three carbon atoms. They are classified as dienoic,
trienoic and polyenoic acids on the basis of number
of double bonds in them.
Linoleic acid and arachidonic acid collectively known
as “Essential fatty acids”. They have to be provided
in the diet as they can not be synthesized in the
body.

17. Depending on the number of
hydrocarbon chain
•Even chain: They have carbon atoms 2, 4, 6
and similar series. Mostly fatty acids are even-
chained. For example, oleic acid (C18).
•Odd chain: They have carbon atoms 3, 5, 7,
etc. They are present in milk. Some fatty acids
are odd-chained. For example, pentadecanoic
acid (C 15).

18. Depending on the length of hydrocarbon
chain
•Short chain with 2-6 carbon atoms.
•Medium chain with 8-14 carbon atoms.
•Long chain with 16 and above, usually up to 24
carbon atoms.
•Very long chain fatty acids (more than 24 C).

19. PROPERTIES OF FATTY ACIDS
1. Hydrogenation: Unsaturated fatty acids may be converted to the
corresponding saturated fatty acids by hydrogenation of the double
bond.
Linolenic → Linoleic → Oleic → Stearic
Hydrogenation of oils can lead to solidification and saturation, e.g.,
Vanaspati.
2. Halogenation: When treated with iodine, the unsaturated fatty acids can
take up two halogen atoms, at each double bond.
For example, Oleic acid + I2 → Di-iodo oleic acid
The number of halogen atoms taken up will depend on the number of
double bonds and is an index of the degree of unsaturation.

20. PHYSICAL CHARACTERISTICS OF
FATTY ACIDS
• The short and medium chain fatty acids are liquids, whereas
long chain fatty acids are solids at 25°C.
• Melting and boiling points increase, with increase in chain
length.
• The unsaturated fatty acids have lower melting point compared
to saturated fatty acids with the same chain length. For
example, stearic acid (C18 fatty acid, no double bond) has the
melting point 69°C, oleic acid (C18, 1 double bond) has 13°C;
linoleic acid (C18, 2 double bonds) has -5°C and linolenic (C18,
3 double bonds) has -10°C.

21. Ester Formation
•Both saturated and unsaturated fatty acids form
esters with alcohols, especially with glycerol.
Fatty acids can form mono-, di- or tri- esters
with alcohol groups of glycerol. For example,

22. Ester Formation

23. ESSENTIAL FATTY ACID
• They cannot be synthesised in the body and must be provided in the diet.
Lack of EFA in the diet can produce growth retardation and other
deficiency manifestation symptoms. Chemically, they are polyunsaturated
fatty acids, namely linoleic acids.
• Functions of EFA:
• It is required for the membrane structure and function.
• Helps in transport of cholesterol.
• Helps in formation of lipoproteins.
• Fats with high content of polyunsaturated fatty acids tends to lower serum
level of cholesterol.
• A deficiency of EFA causes swelling of mitochondrial membrane and
reduction in efficiency of oxidative phosphorylation.

24. Deficiency of EFA
• It results in phrynoderma or toad skin,
characterized by the presence of horny eruptions
on the posterior and lateral parts of limbs on the
back and buttocks, loss of hair and poor wound
healing.
• Fatty liver accompanied by increased rates of
fatty acids synthesis, lessened resistance to
stress.
• Kidney damage

25. TRANS FATTY ACIDS (TFA)
• Trans fatty acids (with double bonds having trans configuration) are
formed during the partial hydrogenation of vegetable oils.
• TFA are more atherogenic than saturated fatty acids.
• They are widely used in food industry because of their long shelf-life.
• They are present in fast food preparation, processed foods, bakery
products, dairy products and in partially hydrogenated vegetable oils.
• They are generally considered to be injurious to health. Oils
containing PUFA also have high content of TFA. Fast food
preparations also have a high TFA content.

26. DIGESTION OF LIPIDS
• Lipids such as triglycerides and phospholipids are converted
into glycerol and fatty acids with help of enzymes such as
lipase and esterase in gastrointestinal tract. Digestion of
triglycerides begins at oral cavity, happens at different levels
in gastrointestinal tract:
• In mouth, small amount of emulsification of phospholipids
takes place with help of lingual lipase.
• In stomach, small amount of dietary triglycerides are broken
down into diglycerides (fatty acid & glycerol) by help of
gastric lipase.

27. DIGESTION OF LIPIDS
• In small intestine, bile & peristalsis helps in emulsification of
the lipids and then pancreatic lipase, phospholipase and
cholesterol esterase. Pancreatic lipase is the principle fat
digesting enzyme and hydrolyzes fats in three stages:
• In the first stage, lipase separates one fatty acid molecule
changing the triglyceride into a diglyceride. The diglyceride is
broken down into another fatty acid molecule and a
monoglyceride. In third stage, the monoglyceride is finally
hydrolyzed into fatty acids and glycerol molecule. Thus,
hydrolysing a fat molecule into fatty acid and glycerol.
Triglyceride → 3 Fatty acids+ Glycerol

28. DIGESTION OF LIPIDS
•Phospholipase hydrolyzes phospholipids to liberate
fatty acids and cholesterol esterase hydrolyzes
cholesterol esters to liberate free cholesterol and fatty
acids.
•In small intestine, intestine lipase also helps in
digestion of lipids, where it hydrolyzes triglycerides,
diglycerides and monoglycerides into fatty acids and
glycerol.

29. ABSORPTION OF LIPIDS
•Most of the fat absorption takes place in duodenum
and jejunum of the small intestine.
•The fats can readily absorbed from the micelles by
microvilli or brush border of intestinal epithelium. The
end products of the fat digestion, i.e. free fatty acids, α
and ẞ-monoglycerides mainly enter microvili by
simple diffusion through cell membrane. The short
chain and unsaturated fatty acids are absorbed more
rapidly than long chain fatty acids, even cholesterol is
also absorbed in the free form through simple
diffusion.

30. Products formed from cholesterol

38. FUNCTIONS OF LIPOPROTEINS
• Chylomicrons carry dietary TG , other lipids and fat soluble
vitamins to liver and other tissues (e.g., adipose tissue).
• VLDL: Synthesized in hepatic cells, they carry endogenous TG
to extrahepatic tissues. TG and VLDL synthesis is increased
with high carbohydrate intake, high insulin/glucagon ratio,
high plasma FFA and alcohol intake.
• LDL: LDL is rich in cholesterol and cholesterol esters (bad
cholesterol) which are delivered to extraheptic tissues.

39. FUNCTIONS OF LIPOPROTEINS
• HDL: HDL scavenges the body cholesterol and blood vessel
wall cholesterol by 'reverse cholesterol transport'. The
mature HDL (good cholesterol) moves to liver where
cholesterol is catabolised.
• HDL competes with LDL (bad cholesterol) on the membranes
and prevents internalisation of LDL cholestrol in the smooth
muscle cells of the arterial walls.
• HDL inhibits platelet aggregation, thus preventing
thrombus formation by the endothelial cells.

40. LIPID PROFILE
A lipid panel or lipid profile test assesses the risk for
cardiovascular disease in a person. It is a combination of
various blood tests, which are performed to measure the
levels of 4 types of lipids in our blood as follows:
• Total cholesterol
• Low-density lipoprotein cholesterol (LDL-cholesterol)
• High-density lipoprotein cholesterol (HDL-cholesterol)

41. Normal Range of Lipid Profile
• Total cholesterol normal range - <200 mg/dL
• LDL cholesterol range - between 70-130 mg/dL
• HDL cholesterol range - between 40-60mg/dL
• Triglycerides - between 10-150 mg/dL
1.Total cholesterol
• Its level between 200-230 mg/dL - Borderline high-risk
• More than 240 mg/dL - High risk
• Total cholesterol score is calculated by adding 20% of TG level,
level of LDL-cholesterol and level of HDL-cholesterol.

42. Normal Range of Lipid Profile
• Total cholesterol normal range - <200 mg/dL
• LDL cholesterol range - between 70-130 mg/dL
• HDL cholesterol range - between 40-60mg/dL
• Triglycerides - between 10-150 mg/dL
1.Total cholesterol:
• Its level between 200-230 mg/dL - Borderline high-risk
• More than 240 mg/dL - High risk
• Total cholesterol score is calculated by adding 20% of TG level,
level of LDL-cholesterol and level of HDL-cholesterol.

43. Normal Range of Lipid Profile
2. LDL- LDL level more than 190 mg/dL is regarded as
very high.
3. HDL- In men, its level <40 mg/dL and in women, <50
The mg/dL indicate high risk.
4. Triglycerides: Borderline high risk - 150-199 mg/dL,
High risk 200-499 mg/dL, Very high risk - 500 mg/dL or
more.
Friedewald's equation :
LDL = Total cholesterol - HDL - Triglycerides/5

44. ATHEROSCLEROSIS
Sclerosis means hardening in atherosclerosis and there
is coronary artery obstruction and myocardial infarction.
• Normal level of cholesterol-150-200 mg/dL
• Total cholesterol <200 mg/dL
• Above 240- treatment is required.

45. Management
•By taking statins e.g. Atorvastatin, a
medicine considerably reduces the level of
LDL.
•PTCA & Stenting

46. Prevention of Atherosclerosis
•Reduce dietary cholesterol.
•Low fat diet
•Intake of green leafy vegetables, i.e., high
fibre content. Leafy vegetables will increase
motility of bowel.
•Light exercise like walking.