Biology 8 Lesson 25: Digestion in the oral cavity
1. Summary of theory
1.1. Digestion in the oral cavity
a. Structure of the oral cavity
The structure of the oral cavity includes:
- Salivary glands.
b. Digestive activities in the oral cavity
Digestion in the oral cavity includes:
- Physical changes: salivation, chewing, mixing food, forming food pellets.
- Effect: make food into soft, puree, saliva-soaked food and easy to swallow.
- Chemical change: Activity of amylase enzyme in saliva.
- Effect: convert a part of starch (ripe) in food into maltose sugar.
1.2. Swallowing and pushing food through the esophagus
Food is pushed down the esophagus by the main action of the tongue and is filled to the stomach by the rhythmic contractions of the esophageal muscles.
– Food passes through the esophagus very quickly (Only 2 to 4 seconds) so it can be considered that the food has not been changed chemically and physically.
When food passes through the esophagus, the epiglottis closes so that food does not enter the trachea.
2. Illustrated exercise
What is the actual physical change of food in the oral cavity?
In fact, the physical change of food in the oral cavity is the cutting, smoothing and mixing of saliva-soaked food.
3.1. Essay exercises
Question 1: Please explain the biological meaning of the idiom “Chewing well and full for a long time”.
Verse 2: With a diet full of nutrients, after digestion in the oral cavity and esophagus, what types of substances are left in the food that need to be further digested?
Question 3: When we eat porridge or drink milk, how can these foods change in the oral cavity?
3.2. Multiple choice exercises
Question 1: The physical transformations that occur in the oral cavity are:
A. Saliva secretion
B. Chewing and mixing food
C. Feed pellets
D. All of the above answers
Verse 2: Feed mixing is performed by the following agencies:
A. Teeth, tongue, cheek muscles.
B. Teeth and tongue
C. Teeth, tongue, lip muscles, cheek muscles
D. Teeth, tongue, lip muscles.
Question 3: The role of feed pelleting activity:
A. Wet and soften food
B. Chopping, softening food
C. Absorb saliva
D. Create the right size, easy to swallow
Verse 4: Food is pushed through the esophagus to the stomach by the action of:
A. The muscles of the esophagus
B. Stomach contractions
C. Epiglottis cartilage
D. Saliva secretion
Question 5: The transformation of food in the oral cavity includes processes.
A. There is only physical change
B. Only chemical change
C. Includes physical and chemical changes
D. Only mechanical transformation
After completing this lesson, you should:
- Describe the activities of digestion in the oral cavity.
- Describe the process of swallowing and pushing food through the esophagus.