Ch 32: Holt McDougal Biology Chapter 32: Digestive & Excretory Systems

About This Chapter

The Digestive & Excretory Systems chapter of this Holt McDougal Biology Companion Course helps students learn the essential lessons associated with the digestive and excretory systems. Each of these simple and fun video lessons is about five minutes long and is sequenced to align with the Digestive & Excretory Systems textbook chapter.

How It Works:

  • Identify the lessons in the Holt McDougal Digestive & Excretory Systems chapter with which you need help.
  • Find the corresponding video lessons with this companion course chapter.
  • Watch fun videos that cover the digestive and excretory systems topics you need to learn or review.
  • Complete the quizzes to test your understanding.
  • If you need additional help, rewatch the videos until you've mastered the material or submit a question for one of our instructors.

Students will learn:

  • Which nutrients support physical activity
  • How to determine nutritional needs
  • Functions of the upper and lower gastrointestinal tracts
  • The small intestine's digestive roles
  • Kidney function and the effects of metabolic disease

Holt McDougal is a registered trademark of Houghton Mifflin Harcourt, which is not affiliated with

7 Lessons in Chapter 32: Holt McDougal Biology Chapter 32: Digestive & Excretory Systems
Test your knowledge with a 30-question chapter practice test
Nutrients to Support Physical Activity

1. Nutrients to Support Physical Activity

It is important to stay well-nourished with carbohydrates, protein, fats and various vitamins and minerals during physical activity. Learn about these nutrients that support physical activity as well as the benefits of water during active times.

Determining Your Nutritional Needs

2. Determining Your Nutritional Needs

This lesson will teach you about important terms involved in determining your nutritional needs, as well as about a tool that can help you use the latest nutritional science to figure these things out.

Digestive System I: The Upper Gastrointestinal Tract

3. Digestive System I: The Upper Gastrointestinal Tract

Did you know that there are digestive enzymes in your saliva? It's true. As soon as you put a piece of food in your mouth, the digestive process begins. Join us with this first of two lessons about the human digestive system, where we'll follow food through the upper gastrointestinal tract from the mouth through the stomach.

Digestive System II: The Lower Gastrointestinal Tract

4. Digestive System II: The Lower Gastrointestinal Tract

The lower gastrointestinal tract is the part of the digestive system that is responsible for the last part of food digestion and the expulsion of waste from the body. In this lesson, we'll look at each part of the system and what functions each serves in the process of digestion.

Small Intestine: Nutrient Absorption and Role In Digestion

5. Small Intestine: Nutrient Absorption and Role In Digestion

The majority of digestion and absorption of nutrients takes place in the small intestine. In this lesson, you will learn about unique modifications within the walls of the small intestine, such as microvilli, villi, and circular folds. These structures increase absorption of nutrients.

Excretory System

6. Excretory System

Each year in the U.S., close to 400,000 people with kidney failure undergo dialysis treatment in order to remove waste, remove excess fluid and restore electrolyte balance. Kidneys, the workhorses of the excretory system, perform these same functions more effectively than any machine. In this lesson, we'll talk about how the excretory system removes toxic substances from the body.

How Kidney and Metabolic Disease Affect Kidney Function

7. How Kidney and Metabolic Disease Affect Kidney Function

This lesson explores chronic kidney disease and the metabolic disorders that affect kidney function. We'll delve into diabetes mellitus, hypertension, and glomerulonephritis and learn what your urine can tell you about your health.

Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
Not Taken
Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
Not Taken

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Other Chapters

Other chapters within the Holt McDougal Biology: Online Textbook Help course