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Biology LibreTexts

18.1: Case Study: Food Processing

  • Page ID
    22578
  • Case Study: Please Don’t Pass the Bread

    Angela and Mariah 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. Mariah agrees and they head to the restaurant.

    At lunch, Mariah asks Angela what is special about her diet. Angela tells her that she can’t eat gluten. Mariah says, “Oh yeah, 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 Mariah that avoiding gluten isn’t optional for her — she has celiac disease. Eating even very small amounts of gluten could damage her digestive system.

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    Figure \(\PageIndex{1}\): JMacPherson; www.flickr.com

    You have probably heard of gluten, but what is it and why is it harmful to people with celiac disease? Gluten is a protein found in wheat and some other grains such as barley, rye, and oats. Therefore, it is commonly found in foods such as bread, pasta, baked goods, and many packaged foods. In 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. 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.

    How can 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 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?