"Digestion and Absorption" Human Nutrition PPT Courseware 5

Description

"Digestion and Absorption" Human Nutrition PPT Courseware 5

Every day we eat a variety of foods to ensure we get adequate nutrition. The types of food vary: rice, steamed buns, various vegetables, fruits, meat, eggs, milk, etc. Some people eat a lot but are not fat, while others eat not more than others but are fat. Why is this?

Thought warm-up

1. What changes happen to the steamed buns from chewing to swallowing?

2. What structures in the oral cavity are involved in the changes of steamed buns?

3. What is the substance that makes steamed buns sweet?

4. What changes does it mean that the steamed buns have become sweeter?

1. Changes in food in the digestive system

Explore

Ask questions: Based on the analysis, ask questions that interest you.

hint:

1. Starch is the main component of steamed buns. Starch has no sweetness. Maltose formed by starch decomposition has sweetness;

2. Starch turns blue when exposed to iodine, while maltose does not change blue when exposed to iodine.

collaborative thinking

1. What is used to simulate the functions of teeth and tongue?

2. How to obtain pure saliva?

3. What is the temperature required for the experiment? What are the test reagents? Why were this temperature and reagents chosen?

4. What are the variables when comparing three test tubes two by two? What is the purpose of comparison?

Analytical thinking

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

2. What substances in the mouth change the properties of starch?

1. Teeth can chop and grind food, tongue can fully mix food with saliva, and saliva can start to change starch.

Connection: The chopping and grinding of the teeth and the full stirring of the tongue can make the saliva more fully mixed with the food debris, and better promote the change of starch.

2. Salivary amylase in the mouth can fully convert part of the starch into maltose

2. Absorption of nutrients

Structural characteristics of the small intestine suitable for absorption

1. The small intestine is very long, about 5-6 meters long.

2. There are many folds on the inner surface of the small intestine, and there are small intestinal villi on the surface of the folds, which increases the inner surface area.

3. There are abundant capillaries in the villi of the small intestine.

ANALYSE information

When Shanshan's child was eating watermelon, she accidentally swallowed a watermelon seed. This watermelon seed experienced a day's adventure in Shanshan's digestive tract. It first encountered a monster with sharp tops and bottoms like a steel rolling mill, which almost crushed it to pieces. Just after escaping the disaster, it encountered "acid rain" again. Later, it got into a long and narrow maze. , it walked here for a long time, and many substances around it mysteriously disappeared; after exiting the maze, it almost entered a dead end, but fortunately it changed direction in time; later, it somehow got mixed up with some very smelly things; finally, it got into a dead end. , they left Shanshan together when Shanshan went to the toilet. Please analyze this watermelon seed:

(1) Where did it meet the rolling mill-like monster?

(2) Where does it encounter "acid rain"?

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

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

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Update Time: 2024-09-23

This template belongs to biology courseware People's Education Press seventh grade biology book volume 2 industry PPT template

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