"Digestion and Absorption" Human Nutrition PPT Courseware 4

Description

"Digestion and Absorption" Human Nutrition PPT Courseware 4

Digestion: After entering the digestive system, organic matter with large molecules and complex structures, such as starch, fat, and protein, is gradually broken down into simple substances before they can be absorbed by the human body. This process is called digestion.

(Textbook page 26)

Nutrients in food are digested and absorbed in the digestive system.

learning target

1. Describe the composition of the human digestive system and the morphology, structure and physiological functions of each organ.

2. Learn to explore the digestion effect of oral cavity on starch. (difficulty)

3. Summarize the digestion process of food in the small intestine and the characteristics of the small intestine that are suitable for its functions. (emphasis)

4. Outline the process of nutrient absorption.

Task one

1. Carefully observe Figure 4-22 on page 29, and refer to the text on pages 26-29 of the textbook to quickly memorize the composition of the digestive system and the functions of each structure.

2. Read the 27 pages of controlled trials, understand the test steps, and analyze: How many groups of controlled trials are there in the trial? How to set variables? What were the results of the experiment? What was the conclusion?

3. Describe the digestion process of carbohydrates, fats, and proteins.

Explore the changes of steamed buns in the mouth

1.Ask a question

Is the sweetness of steamed buns related to chewing of teeth, stirring of tongue and secretion of saliva? If relevant, what role do they play? Does the starch change when steamed buns become sweet?

2. Make assumptions

The sweetness of steamed buns is related to chewing with teeth and stirring with tongue

The sweetness of steamed buns is related to the secretion of saliva

The sweetness of steamed buns is related to chewing of teeth, stirring of tongue and secretion of saliva.

3. Make a plan and complete the experiment

① Take fresh steamed buns and cut them into 3 pieces of the same size. Chop 2 of them into fine pieces with a knife; do not do any processing to the other piece.

②Take saliva

Analysis and discussion

1. What are the differences and connections between the functions of teeth, tongue and saliva?

Difference: Teeth can chop and grind food, tongue can fully mix food and saliva, saliva can break down starch into maltose

Connection: Chewing with teeth and stirring with tongue can fully mix food and saliva to better promote starch digestion.

2. What substances in the mouth cause starch to change?

Salivary amylase in saliva can convert part of the starch into maltose

3. Why should the test tube be placed in warm water around 37°C?

The temperature of the mouth is about 37℃

4. Why do steamed buns feel a little sweet when chewed?

Salivary amylase converts starch into maltose

(1) Where did it encounter a monster like a steel rolling mill?

(2) Where does it encounter "acid rain"

(3) What is the long and narrow "maze"? Why do so many substances mysteriously disappear here?

(4) What is the "dead end"?

(5) Where does it get mixed up with something very smelly?

practise

Analyze the data to indicate which part of the digestive tract contains the most digestive juices.

With a daily intake of 800 grams of food and 1200 ml of water,

The digestive glands secrete roughly the following amounts of digestive juices.

1500 ml saliva 2000 ml gastric juice 1500 ml intestinal juice 500 ml bile 1500 ml pancreatic juice

Oral cavity: 1500 ml saliva; Stomach: 2000 ml gastric juice;

Small intestine: intestinal juice + bile + pancreatic juice, a total of 3500 ml

Therefore, the small intestine has the most digestive juices.

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Update Time: 2024-11-24

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