Chylomicrons

CHYLOMICRONS

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CONTENTS

• Etymology

• Definition

• Structure

• Size

• Origin

• Life cycle

• Transportation

• Importance

• Chylomicron retention disease

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ETYMOLOGY OF CHYLOMICRON

The word "chylomicron" has been derived

from two greek words:

• "Chylos“ means milky

• “Mikros" means small

• Chylomicrons= small milky (globules).

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DEFINITION

• A large plasma lipoprotein particle, occurring

as a droplet consisting primarily of

triglycerides and functioning in the transport

of neutral lipids from the intestine to the

tissues by way of the lymph.

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STRUCTURE OF CHYLOMICRONS

• Chylomicrons are considered large

lipoproteins because of lipid, phospholipid

and protein constituents.

• However, the Protein Constituents are

extremely low although their role in the

chylomicrons metabolism remains vital.

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CHYLOMICRON COMPONENTS

Triglycerides 85-92%

Phospholipids 6-12%

Cholesterol 1-3%

protein 1-2%

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STRUCTURE OF CHYLOMICRON

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SIZE OF CHYLOMICRONS

• According to Scientists, the diameter of these

particles can range from:

• 75 to 1200 nm

• 1200 nm would be largest at its production in

the intestinal cells.

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ORIGIN OF CHYLOMICRONS

• Chylomicrons are formed in the

endoplasmic reticulum of the mucosal

cells within the villi of the duodenum.

• Secreted through the baso-lateral

membrane into the lymphatic system.

• From the lymph to the blood systems

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LIFE CYCLE OF CHYLOMICRONS

Life cycle of chylomicrons consist of three

stages that differ in the constituency of

chylomicrons because some of the protein in

the form of Apolipoprotein will enter the

chylomicron particles as it reaches its

destination via the circulation.

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STAGES OF LIFE CYCLE

The Life Cycle of Chylomicrons can be

illustrated as having three distinct stages.

These stages include:

• The Nascent Chylomicrons

• The Mature Chylomicrons

• The Remnant Chylomicrons

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NASCENT CHYLOMICRONS

• initial form

• formed in the intestinal epithelial cells or

inside the enterocytes.

• released by exocytosis

• central lacteal of vessels to blood via thoracic

duct

• They contain mainly Triglycirides , Cholestrol,

Phospholipids and Apolipoprotien B-48

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MATURE CHYLOMICRONS

• HDL donates apolipoprotein C2 and

apolipoprotein E to the nascent chylomicron,

and convert it to into mature chylomicron.

• Apolipoprotien C2 is the co-factor for

lipoprotien lipase activity.

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REMNANT CHYLOMICRONS

• Once the store of triglycerides become low,the

chylomicron donates it’s Apolipoprotienc2

back to the HDL know it is called remnant

chylomicron

• much smaller in size

• Apolipoprotien B-48 and Apolipoprotien E

• break down via endocytosis

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TRANSPORTATION OF

INGESTED FAT FROM GUT

TO ADIPOSE TISSUE / LIVER

BY CHYLOMICRONS

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TRANSPORTATION OF FATS

• CCK will travel into the blood stream reach

the galblader

• Galblader contraction cause the fat to enter

into the bile.

• The bile will the travel down through bile duct

into the duedenum .

• The bile is going to emulsify the fat turn into

small droplets so that it could be absorb.

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CONTINUED…..

• Enter into the enterocytes

• The fat and the cholestrol will be packed into

chylomicron.

• Released from the basal lateral site of

enterocyte.

• Chylomicron will go into the lacteal

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CONTINUED…..

• From lacteal it will travel into the thoracic

duct.

• The chylomicrom will enter into the

circulatory system .

• In blood stream they going to contain two

new Apo Protien :

• Apo C and Apo E

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Fats

Duedenum

Absorption by Enterocytes

Enter into blood stream

Liver Adipose tissue11/20/2014 19

• When chylomicron

enter into the liver

• APO-E will bind

with the LDL-R

• Chylomicron will

take up by the liver

• And triglycirides

are use by the liver

TRANSPORT OF FATS TO LIVER

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TRANSPORT OF FATS TO ADIPOSE

TISSUE

• Adipose is made up of lipocytes.

• They express the emzye called lipoprotien

lipase.

• Chylomicron will bind to the lipoprotien of

lipase through apo-c

• enzyme is going to cleave the triglycirides into

indidvidual fatty acid and glycerols.

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CONTINUED…..

• Then they absorb into the fats cells.

• The amount of the triglycerides is low

• Chylomicron will lose the APO-C

because of the less amount of

triglycerides.

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ADEPOCYTESOR

FAT CELL

TRANSPORT OF FATS TO ADIPOSE

TISSUE

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CHYLOMICRON

REMNANT TO

LIVER

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IMPORTANCE OF CHYLOMICRONS

• Lipid metabolism

• Fatty nutrients circulation and absorption in

the intestinal cells

• Gather proteins and cholesterols from the

lymphatic system.

• Supply triglycerides and cholesterols to

tissues

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CHYLOMICRON RETENTION

DISEASE

• Chylomicron retention disease is a rare

disease.

• It's an inherited disorder that affects the

absorption of dietary fats, cholesterol, and

certain fat-soluble vitamins.

• A lack of chylomicron transport causes

severely decreased absorption (malabsorption)

of dietary fats and fat-soluble vitamins.

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SYMPTOMS

• The signs and symptoms of chylomicron

retention disease appear in the first few

months of life.

• They can include failure to gain weight

• Failure to grow at the expected rate

• Diarrhea

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ANY QUESTION?

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