Biology 102 Chapter 23

Biology 102 Chapter 23 - Digestive System
Why do we eat?
1. Macronutrients: carbohydrates, proteins, 2. Micronutrients: compounds needed in
and lipids small amounts
●​ For energy: chemical energy stored in ●​ Vitamins: organic
macronutrients is released and used to ●​ Minerals: inorganic
fuel ATP synthesis. ●​ Assist many metabolic
●​ For raw materials: carbon, nitrogen, processes and cellular
and other elements that make up our functions.
cells, tissues, and organs.



Essential Nutrients
Many nutrients are essential
Our bodies can synthesize most of the
molecules it needs.
Essential nutrients cannot be synthesized and
must come from food.
9
●​ Amino acids: 20
are essential for
humans
●​ Fatty acids: ones produced by plants
●​ Certain vitamins & minerals

Food Processing
Food passes through a series of specialized
compartments/organs.
1.​ Ingestion: eating.
2.​ Digestion: food is broken down into
small molecules (amino acids,
monosaccharides, fatty acids).
3.​ Absorption: cells take up the small
molecules.
4.​ Elimination: undigested material is
removed.




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