15.1 Case Study: Food Processing

Created by CK-12 Foundation/Adapted by Christine Miller


15.1.1 Bread
Figure 15.1.1 Bread — Are you a glutton for gluten?

Case Study: Please Don’t Pass the Bread

Angela and Saloni are college students who met in physics class. They decide to study together for their upcoming midterm, but first, they want to grab some lunch. Angela says there is a particular restaurant she would like to go to, because they are able to accommodate her dietary restrictions. Saloni agrees and they head to the restaurant.

At lunch, Saloni asks Angela what is special about her diet. Angela tells her that she can’t eat gluten. Saloni says, “My cousin did that for a while because she heard that gluten is bad for you. But it was too hard for her to not eat bread and pasta, so she gave it up.” Angela tells Saloni that avoiding gluten isn’t optional for her — she has celiac disease. Eating even very small amounts of gluten could damage her digestive system.  It can be difficult for people living with celiac disease to find foods when eating out.

You have probably heard of gluten, but what is it, and why is it harmful to people with celiac disease? Gluten is a protein present in wheat and some other grains (such as barley, rye, and oats), so it is commonly found in foods like bread, pasta, baked goods, and many packaged foods, like the ones pictured in Figure 15.1.2.

Figure 15.1.2 Gluten is a protein present in foods like bread, pasta, and baked goods.

For people with celiac disease, eating gluten causes an autoimmune reaction that results in damage to the small, finger-like villi lining the small intestine, causing them to become inflamed and flattened (see Figure 15.1.3). This damage interferes with the digestive process, which can result in a wide variety of symptoms including diarrhea, anemia, skin rash, bone pain, depression, and anxiety, among others. The degree of damage to the villi can vary from mild to severe, with more severe damage generally resulting in more significant symptoms and complications. Celiac disease can have serious long-term consequences, such as osteoporosis, problems in the nervous and reproductive systems, and the development of certain types of cancers.


Figure 15.1.3 How celiac disease can affect the villi of the small intestine. Here, the villi on the right represent the expected structure of healthy villi. The villi on the bottom right are celiac-affected villi; inflammation has caused them to deform, reducing their ability to function efficiently, if at all.

Why does celiac disease cause so many different types of symptoms and have such significant negative health consequences? As you read this chapter and learn about how the digestive system works, you will see just how important the villi of the small intestine are to the body as a whole. At the end of the chapter, you will learn more about celiac disease, why it can be so serious, and whether it is worth avoiding gluten for people who do not have a diagnosed medical issue with it.

Chapter Overview: Digestive System

In this chapter, you will learn about the digestive system, which processes food so that our bodies can obtain nutrients. Specifically, you will learn about:

  • The structures and organs of the gastrointestinal (GI) tract through which food directly passes. This includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
  • The functions of the GI tract, including mechanical and chemical digestion, absorption of nutrients, and the elimination of solid waste.
  • The accessory organs of digestion — the liver, gallbladder, and pancreas — which secrete substances needed for digestion into the GI tract, in addition to performing other important functions.
  • Specializations of the tissues of the digestive system that allow it to carry out its functions.
  • How different types of nutrients (such as carbohydrates, proteins, and fats) are digested and absorbed by the body.
  • Beneficial bacteria that live in the GI tract and help us digest food, produce vitamins, and protect us from harmful pathogens and toxic substances.
  • Disorders of the digestive system, including inflammatory bowel diseases, ulcers, diverticulitis, and gastroenteritis (commonly known as “stomach flu”).

As you read this chapter, think about the following questions related to celiac disease:

  1. What are the general functions of the small intestine? What do the villi in the small intestine do?
  2. Why do you think celiac disease causes so many different types of symptoms and potentially serious complications?
  3. What are some other autoimmune diseases that involve the body attacking its own digestive system?



Figure 15.1.1

Bread [photo] by Sergio Arze on Unsplash is used under the Unsplash License (https://unsplash.com/license).

Figure 15.1.2

Figure 15.1.3

Inflammed_mucous_layer_of_the_intestinal_villi_depicting_Celiac_disease by www.scientificanimations.com (image 140/191) on Wikimedia Commons is used under a CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0) license.




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Human Biology Copyright © 2020 by Christine Miller is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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