Chapter 3 – Digestion
3.1 Introduction and Learning Objectives
Life is extraordinarily complex. That’s true whether you’re considering something as seemingly simple as a blade of grass or as complicated as the human body. However, when we feel the makeup of living things—from atoms to molecules to macromolecules to cells—we can see similarities and patterns that help us make sense of this complexity.
In this unit, you’ll learn about the scientific method, which forms the foundation for what we know about nutrition. You’ll learn about the different types of research studies and their advantages and limitations. We’ll discuss various sources of information, such as scholarly and popular sources, how each can be useful in different ways, and how to evaluate them. We’ll also discuss careers in nutrition and the different types of skills that you’ll find among nutrition experts.
Because understanding nutrition requires a bit of chemistry and biology, we quickly review atoms and molecules, the simplest substances in food and our bodies, then move to cells. Understanding these is required to appreciate how the human body uses nutrients. The last sections of this unit focus on the digestive system, the site of food processing and nutrient extraction. And while it usually functions as an efficient, coordinated system, we’ll also consider some common ways it can go awry, leading to digestive tract disorders and discomfort or adverse reactions to certain foods.
Chapter 3 Learning Objectives
After completing this chapter, you will be able to:
-
3.1 Describe the levels of structural organization of the human body, from atoms and molecules to cells, tissues, organs, organ systems, and the whole organism, and identify the essential characteristics of cells.
-
3.2 Identify the major organs of the gastrointestinal (GI) tract and explain their primary functions in digestion and absorption, including the five fundamental activities of digestion, with examples of each.
-
3.3 Describe common gastrointestinal disorders and discomforts, including their typical causes, symptoms, and general approaches to prevention and treatment.
Attributions
This section is an adaptation of “Introduction to Molecules of Life” in Nutrition: Science and Everyday Application, V. 1.0 by Alice Callahan, PhD; Heather Leonard, MEd, RDN; and Tamberly Powell, MS, RDN under a Creative Commons Attribution-NonCommercial 4.0 International License.
