Chyme: Definition & Function

Lesson Transcript
Instructor: Sarah Phenix
Chyme is a semi-fluid material consisting of partially digested food and digestive secretions that are expelled by the stomach. Learn about the definition and function of chyme, and explore the role of the stomach in mechanical and chemical digestion. Updated: 11/30/2021

What Is Chyme?

If you've ever gotten sick and thrown up, then you are intimately familiar with what chyme is and the varied ways it can appear. Chyme (pronounced KIME) is that thick, highly acidic, semifluid material formed by the digestive juices of your stomach interacting with the food you've consumed. It's the product of two forms of digestion - mechanical digestion and chemical digestion - and you can't get the nutrients you need without it.

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  • 0:30 Mechanical Digestion
  • 1:19 Chemical Digestion
  • 1:53 The Stomach &…
  • 2:57 The Stomach & Chemical…
  • 3:36 Where Does It Go?
  • 4:18 Lesson Summary
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Mechanical Digestion

Did you know that from the very second you take a bite of food, your digestive process has begun? Your teeth are responsible for mechanical digestion, or physically breaking up food. Their purpose is to take that original food item, like an apple, and break it into smaller pieces. This speeds up digestion and make the entire process easier for your body.

Why are smaller pieces easier to digest? Well, imagine the difference between trying to dissolve an entire piece of rock candy in a glass of water versus granulated sugar. Now, they're both made out of the same thing, but it would take the rock candy a lot longer to dissolve. That's because the granulated sugar crystals have a higher surface area, meaning that more of each crystal is able to interact with the water surrounding it than the larger piece of rock candy.

Chemical Digestion

As you chew and mechanically break down that bite of food into smaller pieces, you're also mixing in your saliva. This is chemical digestion, the breaking down of food using enzymes or acids. Your saliva actually has digestive enzymes in it that specifically break down things like carbohydrates and fats. What about proteins, you ask? Well, that's actually one job of the stomach, and we'll get to that in just a moment. So, once you've chewed your food enough, you swallow it down your esophagus and send it on it's way to chyme production in your stomach.

The Stomach & Mechanical Digestion

Organs of the Abdomen
Organs of the Abdomen

Your stomach is a kidney bean-shaped organ that sits right below your liver. Now, digestion is the sole purpose of this organ and it takes its job very seriously, employing both mechanical and chemical digestion. The walls of your stomach actually have three layers of muscle tissue so that, when they contract they form a rhythmic, wave-like action down the length of your stomach, called peristalsis. This peristaltic action mechanically churns the contents of your stomach, mixing the food you just swallowed with the digestive juices secreted by the lining of your stomach.

Layers of the Stomach
Layers of the Stomach

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