Study GuideBiology–Nutrition and Digestion1. Introduction to Nutrition and DigestionNutritionincludes all the activities by which living organisms obtain materials from their environmentand move them into their cells. Once inside the cells, these materials aremetabolized, meaning theyare chemically processed to build important substances such as:•structural components of the body•enzymes•energy-rich compounds•other materials needed for lifeAll of the elements and compounds taken into an organism for these purposes are callednutrients.1.1 Nutrition in AnimalsAnimals, including humans, areheterotrophs. This means theycannot make their own foodandmust obtain nutrients by eating other organisms. The nutrients animals consume are already formedorganic molecules.However, these molecules usually cannot beused right away. They are often too large or complex tobe absorbed directly by the body.1.2 DigestionTo make nutrients usable, animals must break food down intosimpler formsthat can be absorbedinto the bloodstream and transported to cells. This process is calleddigestion.Digestion allows the body to:•absorb nutrients efficiently•deliver them to cells•use them for energy, growth, repair, and maintenancePreview Mode
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