Biology 8 Lesson 28: Digestion in the small intestine
1. Summary of theory
1.1. Small intestine structure
– Location: Continuity of gastric pylorus
– Length: 2.8 – 3 m
– Surface area: 400 – 500 m2
– The intestinal wall has 4 layers but is thinner than the stomach:
- Outer membrane layer
- Muscle layer: longitudinal, sphincter
- The submucosa has many folds and microscopic hairs
- Mucosal layer: has a dense network of blood capillaries and lymphatic vessels, has many intestinal glands and mucus-secreting cells
- The liver secretes bile
- Pancreas secretes pancreatic juice
- Intestinal glands secrete intestinal secretions and mucus
- The duodenum is the first part of the small intestine into which bile and pancreatic juice are common.
1.2. Food conversion activities in the small intestine
2. Illustrated exercise
What is the major digestive activity in the small intestine?
The main digestive activity in the small intestine is the chemical transformation of food under the action of enzymes in digestive juices (bile, pancreatic juice, intestinal juice).
3.1. Essay exercises
Question 1: What substances in food need to be digested in the small intestine?
Verse 2: With a diet full of nutrients and effective digestion, what is the composition of nutrients after digestion in the small intestine?
Question 3: If a person has symptoms of a lack of acid in the stomach, how can digestion in the small intestine be like?
3.2. Multiple choice exercises
Question 1: Where is the duodenum located?
A. The junction between the small intestine and the large intestine
B. The first part of the small intestine
C. Last segment of small intestine
D. The last segment of the large intestine.
Verse 2: The lining of the small intestine contains:
A. Intestinal glands
C. Mucus secreting cells
D. All of the above answers
Question 3: Which of the following is not the role of the intestinal mucosa?
A. Mixing food
B. Create force to push food down the next part of the intestine
C. Increases food contact area
D. Make food pellets
Verse 4: Where is food mainly absorbed?
A. Small intestine
B. Large intestine
Question 5: Confidential translation includes
A. Bile salts and alkaline salts
B. Bile salts and HCl
C. Bile salts and neutral salts
D. Bile salts and acid salts
After completing this lesson, you should:
- Describe the structure of the small intestine.
- Describe the food conversion activities of the small intestine.