Chapter 3. Digestion, Absorption, and Elimination
Introduction
Learning Objectives
By the end of this chapter, you will be able to:
- Describe the difference between hunger and appetite.
- Describe the anatomy and physiology of the gastrointestinal tract.
- Describe how the accessory organs and each section of the gastrointestinal tract play a role in digestion, absorption and elimination.
- Identify key hormones and enzymes involved in digestion and absorption.
- Describe common gastrointestinal issues.
Have you ever sat on the couch and felt like eating “those” chips, even when you weren’t hungry? Have you ever swallowed food down your windpipe? Have you ever felt bloated after eating something that didn’t agree with you? Have you ever wondered why the acid in your stomach doesn’t corrode the stomach lining? Well, sit tight because you will learn all about those questions (and many more) in this chapter.
One of the first steps in understanding the importance of nutrients (and nutrition) is to understand how they are broken down, absorbed, and used by our bodies. This chapter focuses on the processes that allow us to break down the food we eat and use the nutrients it contains.
Before we learn about food being broken down, let’s take a step back and think about what drives us to eat, or to “eat those chips” even when we aren’t hungry. Let’s start by learning about the difference between appetite and hunger.
