3. INTRODUCTION
The lipids are a heterogeneous group of
substances which have the common
property of being relatively insoluble in
water and soluble in non-polar solvents
or organic solvent such as eather,
chloroform and benzene.
Lipids are bio molecules that contain
fatty acids or a steroid nucleus.
It composed of carbon, hydrogen,
oxygen, phosphorous, nitrogen and
sulphur. But ratio of oxygen is very low.
6. 1.Simple lipids:- These are esters of
fatty acids with various alcohols.
a.Fats and oils:-triglycerides, esters of
fatty acids with glycerol.
Oils are fats in the liquid state.
Triglycerides exist in the solid or liquid
state, depending on the nature of the
constituent fatty acids.
7. Fatty Acids
Fatty acids are aliphatic carboxylic acids. It
contain an even number of carbon atoms (4-
30) in straight chains.
Fatty acids are divided into two types based
on the nature.
1.Saturated fatty acids:- which carbon atom
containing only single bonds, not a double
bonds. eg. Stearic acids and palmitic acids.
8. 2.Unsaturated fatty acids:-which
carbon atom contain one or more double
bonds.
All the common unsaturated fatty acids of
nature are liquids at room temperature. Eg.
Linoleic , oleic acids etc.
A fat which is in the liquid state is known as
an oil.
9. b. Waxes:- these are esters of fatty acids
with an alcohol of high molecular weight,
They do not have double bonds in their
hydrocarbon chains.
They serve as protective coverings on leaf
surface to protect plants from water loss.
These are also secreted by some insects
eg. Bees wax.
Example of waxes lipids is ocean and
lanoline.
10. 2. Compound lipids:-These are esters of
fatty acids and alcohol with additional
compounds.
These are classified as
I.phospholipids:- It containing fatty acids,
alcohol, phosphorous group and
nitrogenous base. It also divided in to two
types,-
a. Glycerophospho lipids:-here the alcohol
part is glycerol. Example lacithin.
11. b.Sphingophospho lipids:- in case of alcohol is
not glycerol, alcohol is sphingosine. Example
sphingomyelin.
II. Glyco lipids:-it is sugar containing lipids. It
consist of a high molecular weight of fatty acids,
alcohol is sphingosine form, carbohydrate and
nitrogenous base. example cerebrosides.
III. Gangliosides:- These contain N-
acetylneuraminic acid, fatty acids, sphingosine
and 3 molecules of hexose. It found in nerve.
12. IV. Lipoprotein:- It contain lipid and protein.
Lipoproteins are divided in to five different
types. Chilomicrons, very low density
lipoprotein, high density lipoprotein, low
density liporotein, free fatty acids
lipoproteins.
The lipoproteins act as a carrier for
transportation of lipid in the blood.
13. 3. Derived lipids:- It derived form simple
and compound lipids by hydrolysis. These
includes
fatty acids,
alcohols,
monoglycerides and diglycerides,
steroids,
terpenes,
cartenoids.
15. DIGESTION OF LIPIDS
The entire fat portion of the diet consist of
triglycerids, which are combinations of
three fatty acids molecules condensed with
a single glycerol molecule.
The main enzyme are the nessecery for
lipid digestion are called lipase. We have
three different types of lipase.
1. Lingual lipase:-That is secretad by lingual
glands in the dorsal surface of the tongue.
16. A small amount of triglycerides is digested
in the stomach by lingual lipase.
2. Gastric lipase:- It is secreted by fundic
area of stomach.
3. Pancreatic lipase:- It is secreted by
pancreas.
17. DGESTION IN MOUTH
Mechanical digestion occurs as our teeth
grind food and break it apart in to smaller
pieces.
Chemical digestion takes place as lingual
lipase, an enzyme in our saliva, begins to
emulsify fat and saliva moistens the food to
make it easier to swallow
18. DIGESTION IN STOMACH
Digestion of lipids is initiated in the
stomach, catalysed by lingual lipase.
When the food reaches our stomach, the
muscles there begin to churn and move to
further break it down. Once it leaves the
stomach, the food has become semi-liquid
substance referred to as chyme.
In stomach 30% of triglycerides are
digested.
19. DIGESTIONINSMALLINTESTINE
when chyme enters the duodenum, hormones
signal the gallbladder to contract. These
contractions push bile, which is made by the
liver, out of the gallbladder and into the common
bile duct, which connects the gallbladder to the
small intestine.
At the same time, the pancreas, located just
underneath the stomach, secretes bicarbonate
ions, which neutralize the pH of the chyme
entering the small intestine, lipases, enzymes
that break down fat.
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27. Most of the triglycerides of the diet are
split by pancreatic lipase into free fatty acids
and 2- monoglycerides.
Now both fatty acids monoglycerides will
freely diffuse.
But some fatty acids are do not freely
diffuse means that is amphipathic nature of
fatty acids they contain both hydrophilic
regions as well as hydrophobic regions.
28. MICELLES
Micelles are constantly breaking down and
reforming, feeding a small poll of
monoglycerides and fatty acids.
First only freely dissolved monoglycerides
and fatty acids can be absorbed, not the
micelles.
29. The monoglycerides and free fatty acids
are carried to the surfaces of the microvilli
of the intestinal cell brush border and then
penetrate in to the recesses among the
moving, agitating microvilli.
Then both the monoglycerides and fatty
acids diffuse immediately out of the
micelles and into the interior of the
epithelial cells.
30. Then enters the smooth ER reassembles
the triglyceride.
Then enters the golgiapparatus, which
modifies and pakages and exported as a
chylomicron. Then chylomicron enters the
lacteal.
Lacteal is the blind ended, lymphatic
vessels, that are found in the villi of the
small intestine.
31. Now chylomicrone is directly enter to the
lymphatic system. The lymphatic system is
directly conected to the circulation to the
blood stream.
32. CONCLUSION
The lipids play many important roles in our
body from providing energy to producing
hormones.
We wouldn’t be able to digest and absorp
food properly without lipids.
Fat is energy dense, containg 9 calories per
gram.
It also used to insulate and protect our
body.
33. We have a layer of fat just below our skin
that helps to keep our internal body
temperature.
Our vital organs have a layer of fat
around them that protect from some injury.
