"Digestion of Food and Absorption of Nutrients" PPT

"Digestion of Food and Absorption of Nutrients" PPT

Part 1: Composition of the digestive system

(1) Digestive tube

1. Oral cavity: It is the beginning of the digestive tract, which contains teeth, tongue, and salivary glands.

2. Pharynx and esophagus: passages through which food enters the body

3. Stomach: Located in the upper left abdomen, it is the most enlarged part of the digestive tract and is sac-shaped. The main function is to temporarily store food and fully mix food and gastric juice.

4. Small intestine: It is coiled in the abdominal cavity and is 5-6m long. The first section is called the duodenum. The small intestine is the longest section of the digestive tract and is the main place for digesting food and absorbing nutrients.

5. Large intestine: It is about 1.5m long. Its starting part is called the cecum, which is in the lower right part of the abdominal cavity. There is a small blind tube connected to the cecum, called the appendix.

6. Anus: It is the terminal opening of the large intestine. Food residues form feces in the large intestine and are excreted from the body through the anus.

(2) Digestive glands

1. Salivary glands: secrete saliva and enter the mouth. The saliva contains salivary amylase.

2. Gastric glands: secrete gastric juice and enter the stomach. The gastric juice can initially digest proteins.

3. Liver: Secretes bile. Bile entering the small intestine does not contain digestive enzymes and has various metabolism, detoxification, and detoxification functions.

4. Pancreas: Secretes pancreatic juice, which contains a variety of digestive enzymes when entering the small intestine.

5. Intestinal glands: secrete intestinal juice, which contains a variety of digestive enzymes when entering the small intestine.

Digestion of food and absorption of nutrients PPT, Part 2: Digestion of food

1. Definition of digestion:

Digestion is the process in which the nutrients of food are hydrolyzed into absorbable small molecular substances in the digestive tract.

2. Digestion methods: physical digestion and chemical digestion.

3. Chemical digestion of various nutrients.

Food digestion and nutrient absorption PPT, Part 3 content: Classroom activities

Activity Explore the role of saliva in starch digestion

【Activity goal】

⒈Design and implement an experimental plan to explore the changes of steamed buns in the oral cavity.

⒉Understand the meaning of food digestion.

【Event Preparation】

Steamed buns, iodine solution, distilled water, small beakers, measuring cylinders, test tubes, etc.

【Procedures and Methods】

⒈What is the question being explored?

The main component of steamed buns is starch. When chewed in the mouth, the steamed buns become sweeter. What changes occur in the starch content of the steamed buns? Is this change related to the functions of teeth chewing, tongue stirring, and saliva secretion?

⒉What assumptions are made?

⑴ After chewing, you can feel the sweetness, and the change of starch in the steamed buns is __________.

⑵The causes of starch changes are:

⒊How to design a plan?

To measure the role of starch digestion in relation to chewing with the teeth, stirring with the tongue, and secretion of saliva, your experiment was divided into ______ groups. In the experimental group that simulates tooth chewing and tongue stirring, the processing method of steamed buns is ____________________, the quality of steamed buns used in each group of experiments should be _______, and the appropriate temperature given should be ____________.

Food digestion and nutrient absorption PPT, Part 4: Absorption of nutrients

Water, inorganic salts, vitamins in food, and small molecule nutrients such as glucose, amino acids, glycerin, fatty acids, etc. formed after digestion of food enter the blood through the epithelial cells of the digestive tract.

Question: What structural features of the small intestine are compatible with its absorption function?

Observe the villi of the small intestine (from outside to inside)

1. What is the difference between the outer surface and the inner surface of the small intestine?

2. Use a magnifying glass to observe the inner surface of the small intestine. What structures can you see?

Food digestion and nutrient absorption PPT, Part 5: Summary after class

Summary: Structural characteristics of the small intestine that are compatible with absorptive function

1. Large absorption area: there are circular folds on the inner surface, small intestinal villi on the folds, and microvilli on the villous epithelial cells.

2. There are abundant capillaries and lymphatic capillaries in the villi of the small intestine to promote absorption.

3. The walls of the villi, capillaries, and lymphatic capillaries of the small intestine are very thin: they are composed of a single layer of epithelial cells, making it easy for nutrients to pass through and improving the efficiency of absorption.

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