Digestive System PDF

## 2.2. Aparato digestivo ### 2.2.1. La digestión During this process, food is broken down and the enzymes in the digestive juices break down the molecules, converting them into smaller molecules that enter the body and can be used by the cells. ### Ahora te toca a ti 1. Fill in the text using the...

## 2.2. Aparato digestivo ### 2.2.1. La digestión During this process, food is broken down and the enzymes in the digestive juices break down the molecules, converting them into smaller molecules that enter the body and can be used by the cells. ### Ahora te toca a ti 1. Fill in the text using the diagram with the main stages of digestion. The process mentioned above (digestion) takes place in the digestive system, which is made up of: * the Mouth * the intestines * the stomach 2. Where does food intake take place? * In the mouth. 3. Where is the absorption of food into the blood? * In the intestines. 4. Where is the egestion of food? * In the large intestines ### 2.2.2. Structure of the digestive system #### a. Digestion in the mouth In humans, the permanent dentition is made up of 32 teeth: * 8 incisors with a cutting crown * 4 canines with a pointed crown * 8 premolars with two chewing points * 12 molars with four or five chewing points The first dentition or milk dentition is made up of 20 teeth: * 8 incisors * 4 canines * 8 molars Externally, you can distinguish three regions in a tooth: * the crown, which is the protruding part * the neck * the root, which is embedded in the tooth socket. In the teeth, the following layers can be distinguished: * Enamel, which is stronger than steel, covers the part of the tooth that protrudes and is made up of 97% calcium salts. * Dentin or ivory, which is less hard than the previous one, is composed of 75% calcium salts. Inside the cavity that exists in its interior, is the tooth pulp, a connective tissue in which nerves and blood vessels are located. * Cement, a thin layer of bone tissue that covers the root. ### Ahora te toca a ti 1. Using the text, write the types of teeth in the permanent dentition. * Incisors, canines, premolars and molars. 2. Write the main parts of the tooth. * The crown * The pulp * The root * Enamel * Dentin * Gums * Blood vessels * Cement 3. The organs involved in digestion in the mouth are the tongue, pharynx and salivary glands. What is their main function? * They facilitate the breakdown, chewing and salivation of food. 4. What is the function of saliva in digestion? * Saliva helps with digestion by facilitating the breakdown of the food bolus. ### b. Digestion Process There are two types of processes in digestion: mechanical and chemical. Food intake and chewing take place in the mouth. Then the food bolus passes through the salivary glands where the digestion of complex carbohydrates begins under the action of the enzyme amylase. The food bolus passes through the pharynx and esophagus and reaches the stomach where it mixes with the gastric juice secreted from its walls, forming chyme. Digestion of proteins begins in the stomach under the action of the enzyme pepsin and HCl (hydrochloric acid). Bile, produced in the liver, disperses fats into small droplets, facilitating the action of the enzyme lipase. Bile salts facilitate the digestion of fats. In the pancreas, enzymes are released that complete the digestion of carbohydrates (amylase), proteins (trypsin) and fats (lipase). Pancreatic juice neutralizes the action of HCl and creates a slightly alkaline environment. Chyme is attacked in the small intestine by enzymes in the pancreatic juice and the intestinal wall. Absorption of digested nutrients takes place here. In the large intestines, water and minerals are absorbed, so the waste products of digestion become more solid. Feces are made up of undigested materials and bacteria that are expelled through the anus. Water, minerals and vitamins are not transformed. ### Ahora te toca a ti | Nutrients | Mouth (saliva) enzymes | Stomach (gastric juice) enzymes | Small intestine (intestinal and pancreatic juice) enzymes | Result of chemical digestion enzymes | |---|---|---|---|---| | Water | - | - | - | Water | | Mineral salts | - | - | - | Mineral salts | | Vitamins | - | - | - | Vitamins | | Carbohydrates | Amylase | - | Trypsin | Glucose | | Proteins | - | Pepsin, HCl | Lipasa, trypsin | Amino acids | | Lipids | - | - | Glycerol + fatty acids | - |