The Role Of Bile In Digestion: Emulsifying Fat

By — John Wiley & Sons, Inc.
Updated on Dec 14, 2010

Food does not physically pass through every organ involved in the digestive process. Some body parts are described as accessory organs because they produce materials that aid digestion. One of these accessory organs is the liver, which secretes and sends bile to the small intestine to help with the breakdown of fats. Bile's main role is to emulsify fats, separating them into small droplets so the body can use them as nutrients. In this activity you will see how bile breaks up fats.


Two small clear cups, each filled with 50ml of water

Two medicine droppers or pipettes

Small container of cooking oil

Small container of dishwashing detergent

Plastic spoon


  1. Add two medicine droppers full of cooking oil to each cup of water.
  2. Observe the appearance of the oil in the water.
  3. Add a dropper full of dishwashing detergent to one of the cups, stirring with the spoon as you release the detergent. Do not add anything to the other cup.
  4. Compare the appearance of the oil in both cups.

Follow-Up Questions

  1. What did the oil look like when you first added it to the water?
  2. What happened to the oil after you added dishwashing detergent to one cup?
  3. In the process of digestion, what nutrient do you think the cooking oil represents? What chemical do you think the dishwashing detergent represents?


  1. The oil spread out and floated on top of the water.
  2. The oil broke up into little droplets.
  3. The cooking oil represents fats or lipids. The detergent represents bile.


Bile is stored in a small sac, the gall bladder, until needed. How do you think the surgical removal of the gall bladder and the subsequent loss of bile might affect a person's digestion? The liver is a multifunctional organ. Research some of the other roles of the liver aside from fat emulsification.

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