detailed procedure of absorption of lipids

1. Human Physiology and
functional histology
Presentation
Absorption of Lipids
Presented by- Arpit Tiwari

2.  A lipid is chemically defined as a substance that is
insoluble in water and soluble in alcohol, ether, and
chloroform.
 Lipids are an important component of living cells.
 Cholesterol and triglycerides are forms of lipid.
These are stored in the body in adipose tissue.
 Another word for lipid is ‘fat’.
 These include fatty acids, neutral fats, waxes and
steroids .

3.  Lipids can serve a diverse range of functions within
a cell, including:
 Storage of energy for long-term use (e.g.
triglycerides)
 Hormonal roles (e.g. steroids such as oestrogen
and testosterone)
 Insulation – both thermal (triglycerides) and
electrical (sphingolipids)
 Protection of internal organs (e.g. triglycerides and
waxes)
 Structural components of cells (e.g. phospholipids
and cholesterol)


4. The digestion and absorption of lipids in human body
takes place mainly in 3 steps:
1. Emulsification .
2. Micelle formation.
3. Absorption.

5.  The dietry fat is insoluble in water so it
has problem in easy digestion.
 The dietry fat which is present in food
reaches undigested into the small
inestine.
 The digestion of lipid occurs in
duodenum.
 The fat is present in the form of a large
fat droplet and thus cannot be acted by
the enzyme ‘Pancreatic Lipase’ which is
responsible for breaking down of fat.
 The bile juice acts on the large fat
droplet and emulsifies it.(breaks large fat
droplet into small droplets).
 This process is known as emulsification.

6.  When pancreatic lipase acts on fat droplets, it
breaks them into 2 components:
Pancreatic lipase+ Fat droplets
This makes further digestion and absorption of lipid
more easy.
Fatty Acids Monoglycerides

7.  After digestion fatty acids and
monoglycerides associate with bile
salts and phospholipids to form
micelles.
 The size of micelles is 200 times
smaller than emulsion droplets.
 Micelles are necessary because they
transport the poorly soluble
monoglycerides and fatty acids to
the surface of the enterocyte where
they can be absorbed.

8.  The major products of lipid digestion - fatty acids and 2-
monoglycerides - enter the enterocyte by simple diffusion across
the plasma membrane.
 Once inside the enterocyte, fatty acids and monoglyceride are
transported into the endoplasmic reticulum, where they are used
to synthesize triglyceride.
 Beginning in the endoplasmic reticulum and continuing in the
Golgi, triglyceride is packaged with cholesterol, lipoproteins and
other lipids into particles called chylomicrons.
 Chylomicrons are lipoproteins, special particles that are
designed for the transport of lipids in the circulation.
 The above process takes place in absorptive enterocyte of small
intestine.

9.  The chylomicrons are now
exported.
 Chylomicrons can not move in
blood stream directly so they
move to the lacteal of the
lymphatic system.
 Lacteal are blind ended
lymphatic vessels that are found
in the villi of small intestine.
 The lymphatic system is direcly
connected to circulation hence
these chylomicrons are mixed in
blood and then stored in the
adipose tissue of the body.

10. Thank You !