Question

Write a short note on digestion of fats in human body.

Answer 1

• Fat digestion occurs in following steps-

1) In the mouth and stomach:-

• Digestion of fats starts in the mouth.
• Mechanical digestion occurs as the teeth grinds and breaks it apart into smaller pieces.
• Chemical digestion takes place as the enzyme lipase in the saliva begins to emulsify fat and saliva moistens the food to make it easier to swallow.
  
• In the stomach, the muscles there begin to churn and move to further break it down.
• As it leaves the stomach, the food becomes a semi-liquid substance known as chyme.
  

2) In small intestine:-

• As the chyme enters the duodenum, the pancreas secretes bicarbonate ions, which neutralize the pH of the chyme entering the small intestine and lipases break down fat.

3) Creation of micelles:-

• Fats are hydrophobic (do not dissolve in water).
  
• Bile molecules have a hydrophobic as well as a hydrophilic end.
• The hydrophobic end sticks to each fat molecule and the hydrophilic protrudes to prevent the molecules from sticking together.
• The combined structures of fat molecules and bile molecules are called micelles.
  

4) Breakdown of micelles:-

• Lipases act on the micelles and break down fat molecules into fatty acids and monoglycerides that passes through the small intestine.
• After they pass through the small intestine the fatty acids get converted to triglycerides which combine with cholesterol, phospholipids and protein to form a structure called a chylomicron.
• The protein coating of the chylomicron makes it water-soluble so it can travel through the lymph vessels and eventually reach the bloodstream.