The Human Digestive System, What Is Its Role
The Digestive -System: – The human digestive system consists of a long and convoluted tube, in which food is broken down physically and chemically so that the nutritional eleniients it contains can be absorbed. The digestive system begins with the lips, teeth, mouth, and tongue, which form a chamber in which food is moistened and crushed before it starts its passage through to the stomach and intestine. Most absorption occurs in the long, narrow, small intestine.
The digestion of starch begins in the mouth in the presence of saliva. The crushing and softening of food in the mouth is called mastication. Sali a ;s rich in ptylin (salivary amylase), an enzyme that starts the conversion of starches into simple sugars. The esophagus is a short tube between the lower pharynx (throat) and the stomach.
The stomach secretes gastric juice which contains hydrochloric acid, salts, pepsin (enzyme) and water. Stomach digests proteins.
The rest of the digestion and absorption takes place in the small intestine. Absorption of water and salts takes place in the large intestine.
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