You and your friend decide to go to out to eat at a popular burger joint. Your f

Question

You and your friend decide to go to out to eat at a popular burger joint. Your friend is extremely hungry and orders the quarter pound bacon burger and cheese fries. Answer the following questions regarding the digestion of fat immediately following meal consumption. 14 points total.

(A) Explain how fats are emulsified and its purpose (3 pts)?

(B) Explain the process of fats absorption across the epithelium of the small intestine (3 pts)?

(C) After fat is absorbed across the small intestinal epithelium, it enters the __________, then _________, where it travels to the _____________(type of tissue) for storage or ___________ (type of tissue) for energy production (4 pts).
(D) When triacylglyerol reaches the tissues for storage or energy production, what happens to the glycerol backbone after the three fatty acids are hydrolyzed (2 pts)?
(E) What is the definition and main physiological purpose of apoplipoproteins (2 pts)?

Explanation / Answer

A. ANS: Fats emulsification and its purpose:

Emulsification is a process of breakdown of splits big fat globules into small ones (fat droplets). Fats are insoluble in water.

Bile contains no digestive enzymes, it helps in fat digestion and absorption it including vitamin A,D,E and K.

Breakup of fats into tiny droplets to increase surface area for lipase activity. Bile salts emulsify the fat for proper lipase activity.

B. fats absorption across the epithelium of the small intestine:

Step 1: Bile salts breaks large fat globules into small droplets.

Step 2: Small droplets are digested by pancreatic lipase enzymes and it yields free fatty acids & monoacylglycerides. then these associate with bile salts to form micelles which "ferry" them to the intestinal mucosa.

Step 3:Free fatty acids & monoacylglycerides leaves micelles and diffuse into epithelial cells of small intestine. Then they packed with other proteins and fatty acid substances to form chylomicrons.

Step 4: Chylomicrons are extruded from the epithelial cells by endocytosis.

C. ANS:

1. Blood vessels

2. Blood stream (Hepatic portal vein)

3. Liver

4. Adipose tissue

D. ANS: Glycerol Oxidation:

cAMP a secondary messenger that promote phosphorylation and activation of TAG lipase, it leads to hydrolysis of TAG's into free fatty acids and glycerol in the adipose tissue.

Complete oxidation of glycerol into 3 Co2 yields 22 ATP.

E. ANS:

Apoplipoproteins or Apoproteins:

Apoplipoproteins are the protein components of lipoproteins, these lipo protein complexes can help to transport lipids in blood.

The Apolipoproteins are apo-B 100, apoC II and apo E.

The lipoprotein particles, cofactors, enzymes and cell surface receptors are transported by apoplipoproteins.

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