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Section 38-1: Food and Nutrition
The nutrients that the body needs are water, carbohydrates, fats, proteins, vitamins, and minerals.
Every cell in the human body needs water because many of the body's processes, including chemical reactions, take place in water.
Section 38-2: The Process of Digestion
The digestive system includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. Several accessory structures, including the salivary glands, the pancreas, and the liver, add secretions to the digestive system.
The function of each organ of the digestive system is to help convert foods into simpler molecules that can be absorbed and used by the cells of the body.
Section 38-3: The Excretory System
Together, the skin, lungs, and kidneys—along with their associated organs—make up the excretory system.
The kidneys play an important role in maintaining homeostasis. They regulate the water content of the blood and, therefore, blood volume; maintain blood pH; and remove waste products from the blood.