Fat Metabolism

Question 1

What are the 3 main important fatty acids we absorb?

Answer 1

Palmitic (most abundant)
Stearic
Oleic acid

Question 2

Where does triglyceride digestion occur?

Answer 2

Mouth and stomach (limited)
Small intestine (predominantly)

Question 3

What is the major fat digesting enzyme and where is it synthesized?

Answer 3

Lipase

Pancreas

Question 4

What does lipase break triglycerides into?

Answer 4

Monoglyceride and 2 fatty acids

Question 5

Where does lipid digestion start?

Answer 5

In the mouth

Question 6

The lipids in ingested food are ….. in water so…..in the upper portion of the …..

Answer 6

Insoluble

Aggregate into large lipid droplets in the upper portion of the stomach

Question 7

These aggregated lipids are converted into very small droplets by…

Answer 7

Emulsification

Question 8

What are the 2 things required for emulsification?

Answer 8

Mechanical disruption - motility

Emulsifying agent - bile (or phospholipids in food)

Question 9

What happens in emulsification?

Answer 9

Make fat droplets smaller, bile salts emulsify drop,ets further making them even smaller
BS coat the outside of the droplets to ensure they don’t reaggregate & form bigger droplets (join together)

Question 10

What are bile salts formed from?

Answer 10

Cholesterol in the liver and are amphiphatic

Question 11

What does amphiphatic mean?

Answer 11

Both hydrophilic and phobic

Question 12

The coating of the lipid droplets with these emulsifying agents however, …..

Answer 12

Impairs the accessibility of the droplet for lipase

Lipase can’t bind

Question 13

To overcome this issue, what is secreted and where is it secreted from and what does it do?

Answer 13

Colipase
Protein (coenzyme) from pancreas
Helps lipase bind, binds to droplet and lipase

Question 14

These droplets are further converted into smaller droplets called……
These consist of…

Answer 14

micelles

Bile salts, fat soluble vitamins (ADEK) & cholesterol, FA, monoglycerides & phospholipids

Question 15

Where are the contents of the micelles released at?

Answer 15

Contents released at intestinal brush border
(Low solubility in water so diffuse across lipid portion of luminal plasma membrane of epithelial cells of Small, intestine)

Question 16

What happens in the small intestine cells?

Answer 16

Triglycerides reform in SI smooth endoplasmic reticulum

Question 17

What happens after the triglycerides reforms in SI?

Answer 17

Packaged into vesicles with cholesterol and vesicles modifies by Golgi apparatus

Question 18

At the Golgi, what are the vesicles modified into?

Answer 18

Chylomicrons

Question 19

What happens to the chylomicrons? How do they get into the blood capillaries?

Answer 19

Fuse with plasma membrane, exocytose into IF then lacteals (lymphatic vessels in the intestinal villi) then lymphatic circulation and then into systemic veins

Question 20

Where does fat absorption occur?

Answer 20

Jejunum & ileum