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Question

Difficulty: MediumAnimal Nutrition and Digestive System

Bile salts are synthesized in the liver and stored in the gall bladder before being secreted into the duodenum. Although bile salts do not contain any digestive enzymes, they are essential for the digestion of lipids. What is the primary physiological role of bile salts during fat digestion?

  1. Emulsifying large fat droplets into tiny droplets to increase the surface area for pancreatic lipase activityAnswer
  2. B
    Hydrolyzing triglycerides directly into free fatty acids and glycerol molecules
  3. C
    Providing an acidic pH in the small intestine to activate pepsinogen into pepsin
  4. D
    Converting excess glucose into glycogen for storage within intestinal epithelial cells

Answer

Emulsifying large fat droplets into tiny droplets to increase the surface area for pancreatic lipase activity
The correct answer highlights that bile salts perform emulsification, a mechanical process that disperses large fat globules into minute droplets. Because lipase is a water-soluble enzyme acting on water-insoluble fats, emulsification greatly expands the surface area available for pancreatic lipase to digest triglycerides into fatty acids and glycerol.

Step-by-Step Solution

1
Identify the nature of bile salts
Bile salts are non-enzymatic amphipathic molecules secreted by the liver into the duodenum.
Because they lack catalytic activity, they cannot break chemical bonds in nutrients directly.
2
Determine the physical action of bile salts on hydrophobic lipids
Lipids aggregate into large droplets in aqueous chyme. Bile salts lower surface tension, dispersing fats into microscopic droplets (emulsification).
Emulsification expands the lipid-water interface area.
3
Relate emulsification to enzyme action
Pancreatic lipase operates at the aqueous interface to hydrolyze fats into fatty acids and glycerol efficiently.
Increasing surface area accelerates the rate of enzymatic lipid digestion.

Key Concept

Role of bile in emulsification and physical breakdown of lipids
Estimated Time:1m 0s
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Topics

Animal Nutrition and Digestive System

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