DigSystem_nutrition - The Digestive System The human body...

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1 The Digestive System & Nutrition The human body is made up of approximately 60 trillion cells which all work together. Each cell requires energy, nutrients, and oxygen . Each cell also requires removal of waste products and carbon dioxide . The Digestive System As humans, we derive all of our energy and nutrients from the food we eat. However, our food is not suitable for direct use in the form in which we receive it. Our food is processed by the digestive system into smaller units that are usable by the body. The energy and nutrients from the digestive system are then delivered to the body cells through the circulatory system. The Digestive System Mouth --> Esophagus --> Stomach --> Small Intestine --> Large Intestine --> Anus The digestive system is essentially a long tube (~30 ft.) from the mouth to the anus. The overall path of food through the digestive system is: Pieces of food are ground into small bits by the teeth and are mixed with saliva . Saliva contains proteins called mucins which work with the teeth and tongue to form a slimy ball called a bolus which can be easily swallowed. Saliva also contains a special enzyme called amylase which breaks down starch into simple sugars. Food is then swallowed and moves to the esophagus. Mouth Esophagus The esophagus is a muscular tube from the mouth to the stomach. Food moves down the esophagus to the stomach by peristalsis , wave-like muscle contractions that move the food in one direction.
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2 Stomach -The stomach is a muscular sac with a thick, protective, mucus lining. The environment inside the stomach is highly acidic (pH ~1.5). The mucus lining of the stomach protects the rest of the body from this acidic solution. The major enzyme in the stomach is called pepsin which breaks down proteins into smaller, usable, units. Stomach acid and
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DigSystem_nutrition - The Digestive System The human body...

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