Biology 8 Lesson 24: Digestion and digestive organs
1. Summary of theory
1.1. Food and Digestion
– Every day, in our body, oxidation processes of organic substances such as proteins, lipids, and carbohydrates take place to generate vital energy needed for cellular activities. The role of food is to make up for this loss. In addition, food is also a material to build new cells to replace dead cells and help the body grow.
+ Food after eating will be converted into nutrients for absorption.
- Food consists of organic and inorganic matter
- Organic substances: proteins, lipids, carbohydrates…. : chemically changed during digestion.
+ Inorganic substances: Water, mineral salts: not chemically changed during digestion
– Digestive process includes the following activities: Eating and drinking → pushing food into the digestive tract → digesting food → absorbing nutrients → excreting feces.
The role of digestion: converts food into nutrients that the body can absorb and eliminates waste products out.
1.2. Digestive organs
Oral cavity includes teeth and tongue.
The pharynx is the passage between the oral cavity and the esophagus.
The esophagus is the passage that carries food from the pharynx to the stomach.
The stomach is the widest part of the digestive tract, located in the middle of the abdomen slightly to the left.
+ The small intestine is 2.8 – 3m long, located in the middle of the abdominal cavity.
The large intestine is inverted U-shaped.
The straight intestine is where feces are stored.
+ The appendix is on the lower right side, which is a remnant of an organ in the animal body.
- The appendix no longer functions, which can be frustrating.
2. Illustrated exercise
How can substances in food be grouped? What are the characteristics of each group?
– Substances in feed can be grouped according to the following characteristics:
Based on the chemical structure:
- Organic substances include: Glucose, lipids, proteins, vitamins.
- Inorganic substances include: Mineral salts, water.
+ Based on the characteristics of changes through digestive activity:
- Substances that are changed through digestion: Glucose, lipids, proteins, nucleic acids.
- Substances that are not changed through digestion: Vitamins, mineral salts, water.
3.1. Essay exercises
Question 1: What is the role of digestion in the human body?
Verse 2: The substances needed for the body such as water, mineral salts, vitamins, when entering the body through the digestive tract, what activities of the digestive system need to go through? Can the human body receive these substances in any other way?
Question 3: What is the difference between digestion and digestive activity?
3.2. Multiple choice exercises
Question 1: The activities that occur during digestion are:
A. Absorption of nutrients
B. Eat and Drink
C. Discharge of feces
D. All of the above answers
Verse 2: Arrange the following processes according to the process of digestion occurring in the body.
A. Eating and drinking => transporting food in the digestive tract => digesting food => absorbing nutrients => excreting feces.
B. Eating and drinking => digesting food => transporting food in the digestive tract => absorbing nutrients => excreting feces.
C. Eating and drinking => transporting food in the digestive tract => absorbing nutrients => digesting food => excreting feces.
D. Eating and drinking => absorbing nutrients => transporting food in the digestive tract => digesting food => excreting feces.
Question 3: Substances that cannot be absorbed by the body are:
A. Single track
B. Amino Acids
C. Mineral salts
Verse 4: The digestive glands are:
A. Salivary glands
B. Thyroid gland
C. Intestinal glands
D. All of the above answers
Question 5: Digestion is carried out by the action of:
A. Digestive glands
B. Organs in the gastrointestinal tract
C. Enzyme activity
D. Organs in the alimentary canal and digestive glands.
After completing this lesson, you should:
- Describe the stages of the digestive process.
- Describe the role of digestion.
- Identified on imaging the digestive organs in humans.