MCQ Detailed View

Fat digestion in the human body is a complex biochemical process that primarily occurs in the small intestine. While the digestive process begins in the mouth through chewing and mechanical breakdown of food, the mouth plays almost no role in the chemical digestion of fats. Unlike carbohydrates, which are partially digested by salivary amylase, fats remain largely undigested until they reach the small intestine.

When food enters the small intestine, the liver secretes bile, which is stored in the gallbladder and released into the small intestine. Bile contains bile salts, which play a crucial role in emulsifying fats. Emulsification breaks down large fat globules into much smaller droplets, greatly increasing their surface area for enzyme action. This step is essential because fats are hydrophobic and do not mix well with water-based digestive fluids.

Following emulsification, the pancreas secretes pancreatic lipase, the primary enzyme responsible for breaking down triglycerides (the main form of dietary fat) into glycerol and free fatty acids. These smaller molecules can then be absorbed through the lining of the small intestine into the bloodstream.

In contrast, the large intestine is responsible for water and electrolyte absorption, not fat digestion. The spleen, on the other hand, is part of the lymphatic system and is involved in filtering blood and immune functions, not digestion.

Thus, the small intestine is the key site where the majority of fat digestion and absorption occurs, making it essential for human nutrition and energy storage.

✅ Key Facts Recap

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  Fat digestion occurs mainly in the small intestine

  
  


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  Bile salts (from liver) emulsify fats

  
  


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  Pancreatic lipase breaks down triglycerides into glycerol + fatty acids

  
  


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  Mouth → no chemical fat digestion

  
  


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  Large intestine → water absorption only

  
  


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  Spleen → not part of digestion

  
  

👉 Correct Answer: Small intestine