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Pharmacology · chapter 29 · Introduction to the Digestive System

Introduction to the Small and Large Intestines

The 13 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.

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Key points

  1. Main jobs of the small intestine

    The primary functions of the small intestine are absorption and digestion; the small intestine is responsible for 90%–95% of nutrient absorption.

  2. Bile breaks down fat

    Bile acids from the liver and gallbladder enter the small intestine and break down fat for absorption in the small intestine.

  3. Lipase and fat-soluble vitamins

    Lipase, together with bile salts, breaks down fats and aids absorption of fat-soluble vitamins (A, D, E, K). Poor fat absorption may result in steatorrhea (fatty bowel movements).

  4. Protease and amylase

    Protease breaks down protein for absorption. Amylase is released from the pancreas into the proximal small intestine to break down and absorb carbohydrates.

  5. Villi absorb water and nutrients

    Unique to the small intestine are tiny fingerlike projections called villi that line the walls of the small intestine. The villi protrude into the lumen to absorb water and nutrients into the circulatory system.

  6. Blood capillaries and lacteals

    The blood capillaries absorb carbohydrates and proteins. The lymph capillaries, also called lacteals, absorb fats.

  7. Damaged villi cause malabsorption

    Disorders affecting the intestinal villi of the small intestine may result in malabsorption or nutritional disorders.

  8. The colon forms stool

    The large intestine, also known as the colon, receives waste products from the small intestine. Water is further absorbed from the waste products in the large intestine and forms stool.

  9. By the rectum, most water is gone

    Under expected conditions, when waste products reach the rectum, most of the water has been reabsorbed into the body, leaving solid stool for evacuation from the body.

  10. Colon bacteria and vitamins

    The bacteria in the large intestine are responsible for absorbing vitamin K and B vitamins, including biotin (Thursby Juge, 2017).

  11. Symptoms of IBS

    Symptoms may include bloating, gas, abdominal pain or discomfort, abdominal spasms, cramping, and constipation or diarrhea (or both).

  12. IBS subtypes

    Because people experience varying types of symptoms, IBS is further categorized as IBS-C (constipation), IBS-D (diarrhea), IBS-M (mixed symptoms of diarrhea and constipation), and IBS-U (unsubtyped, with varying inconsistent symptoms).

  13. Managing IBS with lifestyle

    Although IBS is a chronic condition, most people with IBS can manage their disease with lifestyle changes such as consistently eating healthy, balanced meals; staying hydrated; and reducing stress.

Terms to know

villi
Unique to the small intestine are tiny fingerlike projections called villi that line the walls of the small intestine.
lacteals
The lymph capillaries, also called lacteals, absorb fats.
steatorrhea
Poor fat absorption may result in steatorrhea (fatty bowel movements).
Irritable bowel syndrome (IBS)
Irritable bowel syndrome (IBS) is a common disorder affecting the intestine.

Practice questions

Stuck on select-all-that-apply? How to take them one option at a time.

The graded version needs JavaScript. Every question is below anyway, with the answer and why.

Every question here, with the answer

  1. A client with poor fat absorption reports pale, greasy, foul-smelling stools. Which term should the nurse use to document this?

    1. Dysphagia
    2. Melena
    3. Gastroparesis
    4. Steatorrhea

    Answer: Steatorrhea

    Poor fat absorption may result in steatorrhea, which means fatty bowel movements. Gastroparesis is delayed gastric emptying, and dysphagia is difficulty swallowing; none of the others describe fatty stool.

  2. A client has a disorder that damages the intestinal villi. Which problem should the nurse anticipate?

    1. Increased saliva production
    2. Malabsorption
    3. Faster stomach emptying
    4. Excess vitamin absorption

    Answer: Malabsorption

    The villi absorb water and nutrients, so disorders affecting them may cause malabsorption or nutritional disorders. The other options are not linked to damaged villi.

  3. A client with poor fat absorption is at risk of low levels of which vitamins? Select all that apply.

    1. Vitamin A
    2. Vitamin K
    3. Vitamin E
    4. Vitamin C
    5. Vitamin D

    Answer: Vitamin A, Vitamin K, Vitamin E, Vitamin D

    Lipase and bile salts break down fats and aid absorption of the fat-soluble vitamins A, D, E and K, so poor fat absorption puts these at risk. Vitamin C is not among the fat-soluble vitamins listed.

  4. A client newly diagnosed with irritable bowel syndrome asks how to manage it. Which lifestyle changes should the nurse recommend? Select all that apply.

    1. Stay hydrated.
    2. Eat healthy, balanced meals consistently.
    3. Reduce stress.
    4. Limit fluids to reduce diarrhea.
    5. Skip meals when symptoms start.

    Answer: Stay hydrated., Eat healthy, balanced meals consistently., Reduce stress.

    Most people with IBS can manage it by consistently eating healthy, balanced meals, staying hydrated and reducing stress. Skipping meals and limiting fluids work against those recommendations.

  5. A client's IBS is labelled IBS-M. What does the nurse understand this to mean?

    1. Mixed diarrhea and constipation
    2. Mainly diarrhea
    3. Mild symptoms only
    4. Mainly constipation

    Answer: Mixed diarrhea and constipation

    IBS-M means mixed symptoms of diarrhea and constipation. IBS-C is constipation, IBS-D is diarrhea, and the subtype letter does not describe severity.

  6. A student asks what the bacteria of the large intestine do. What is the correct answer?

    1. They absorb most dietary protein.
    2. They absorb vitamin K and B vitamins.
    3. They secrete hydrochloric acid.
    4. They produce bile.

    Answer: They absorb vitamin K and B vitamins.

    Bacteria in the large intestine absorb vitamin K and B vitamins, including biotin, and promote fermentation of indigestible material. Bile comes from the liver, protein is absorbed in the small intestine, and acid is made in the stomach.

Where every quote comes from

Section 29.3 Introduction to the Small and Large Intestines of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.

The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.