Outline of a lesson in biology on the topic “Basics of rational nutrition”

Lesson summary “Digestive organs” lesson plan in biology (8th grade) on the topic

Biology lesson notes (8th grade)

Teacher: Alfimova Ksenia Vladimirovna

DIGESTIVE ORGANS

The purpose of the lesson: to introduce students to the meaning of digestion, to study the organs of the digestive system and digestive glands, to develop the ability to analyze, draw logical conclusions, and cultivate the right attitude towards nutrition and one’s health.

Textbook: “Biology. Man" 8th grade, A.G. Dragomilov, R.D. Mash, publishing house "Ventana-Graf".

The lesson uses technology for developing critical thinking through reading and writing.

During the classes

1. Organizing time
2. Checking homework

Frontal conversation on the following issues:

1. What is the meaning of food?
2. From the list provided, select products of animal and plant origin: cottage cheese, meat, eggs, carrots, beets, bread, butter, sugar, chocolate, potatoes, cheese, nuts.
3. How is food different from nutrients?
4. What nutrients do you know?
5. What is the importance of proteins and fats in the human body?
6. What foods are richest in proteins? Fats?
7. What is the importance of carbohydrates in the human body?
8. What foods are richest in carbohydrates?
9. What is the role of mineral salts in the human body?
10. Why should food contain vitamins?

1. Learning new material

Any food product that enters the body consists of nutrients. Why do substances suitable for food, for example, milk or chicken broth, introduced directly into the blood, cause the death of a person?

Student answers.

In order for food to provide the body with substances and energy, it must be converted into a form accessible for absorption. What organ system digests proteins, fats and carbohydrates?

Formulate the topic of the lesson. Write down the topic in your notebooks and draw a labeling table.

"Challenge" stage

The human digestive system performs three main functions: secretory, motor and absorption. Who can describe them by these names?

Attention to the board: there is a table in front of you, you need to correlate the name of the function with its essence.

We have figured out the meaning of the digestive system, and now let's remember what sections are present in the digestive system of mammals?

Are the digestive systems of mammals and humans similar? Why?

Let's depict the digestive system on the board in the form of a structural and logical diagram.

Do you think this is sufficient information? Then let's try to supplement it.

Stage of “Comprehension of content”

Here is the text of §30. Start working with the text by making notes in the margins:

“v” – familiar information, “+” – new information, “? ” – unclear information

Don't forget to work with the labeling chart. After reading the text, fill out the 3rd column “Learned something new.” (This is not a simple rewriting of the text, but the ability to formulate a thought in 2-3 words, translate it into your language, and, therefore, understand it). Entries should be succinct but concise.

Digestive system

Digestive system: alimentary canal (oral cavity, pharynx, esophagus, stomach, intestines) and digestive glands.

Oral cavity. First the food goes into the mouth. In the oral cavity, it is crushed by the teeth and rubbed with the tongue. Receptors located in the tongue allow us to determine the taste of food and its suitability for eating. The ducts of numerous small and three pairs of large salivary glands flow into the oral cavity. Saliva contains substances that kill germs.

Pharynx and esophagus. Food enters the stomach through the pharynx and esophagus. If you open your mouth wide and examine the entrance to the pharynx, you can see the hard palate in the upper part of the oral cavity, and then the soft palate. The uvula hangs from above, at the very entrance to the pharynx. Along the edges, to the left and right of it, are the tonsils. They consist of lymphoid tissue that performs a protective function. Normally they are pale pink in color. The tonsils are filled with leukocytes, which are ready to fully meet microbes that enter with food and air. With chronic inflammation of the tonsils - tonsillitis - their function is impaired. Diseased tonsils become a reservoir of infection. Tonsillitis requires mandatory treatment.

Place your hand on your throat and make a swallowing motion. You will feel your larynx rise. The entrance to it was blocked by the epiglottis. The uvula (part of the soft palate) rose at this time, blocking the path of food into the nasal cavity. A slippery lump of food moistened with saliva (or saliva, if there was no food) from the oral cavity and pharynx went through the esophagus into the stomach. Recall that the esophagus passes from the chest cavity into the abdominal cavity, where the stomach is located, through an opening in the diaphragm.

Stomach. In the stomach, food is digested under the action of gastric juice, and then enters the intestines in a semi-digested form.

The stomach is located under the diaphragm on the left side. At the top it is filled with air. The airlock prevents food from escaping back into the esophagus. The same function is performed by special circular muscles located at the entrance of the esophagus to the stomach.

When food is digested, numerous gases are formed. When a lot of them accumulate, they break into the esophagus - belching occurs. This can happen, for example, if you drink too many carbonated drinks.

Intestines. From the stomach, food enters the small intestine. Its initial section is called the duodenum. The pancreatic ducts and the common bile duct flow into it, through which bile from the liver and gallbladder enters the intestines.

The small intestine forms several loops. The final digestion of food and absorption of nutrients into the blood and lymph occurs in the small intestines. Where the small intestine flows into the large intestine, the initial section of the latter is located - the cecum with the appendix.

The large intestine goes up, then at the diaphragm it moves to the left side, goes down, forming its last section - the rectum. Through it, undigested food remains are removed. In this part of the intestine, food debris accumulates and must be removed from the body. In the colon, water and mineral salts used in digestion are absorbed back into the blood.

Digestive glands. They secrete digestive juices that digest food, convert complex nutrients into simpler and water-soluble ones. The digestive glands include the salivary glands, microscopic glands of the stomach and intestines, the pancreas and the liver, which secretes bile. Part of the secreted bile goes directly into the duodenum, part - into the gallbladder. There it accumulates and is then used up as needed.

“Reflection” stage

What new did you learn from this text? What were you already familiar with? What surprised or impressed you?

To reinforce this, you can play several games.

"What it is?" Two people are participating, the rest are fans. One person receives a list of terms and in 1 minute he must explain the meaning to the other so that he can guess what term he is talking about.

“Find out the organ from the table” One receives a list of organs that he needs to show on the table, and the second names these organs. Time – 1 minute. (list of organs - pharynx, liver, appendix, small intestine, pancreas, esophagus, rectum, stomach, gall bladder, oral cavity, colon).

“Yes-no” In 1 minute, one of the participants reads out the statement, the second says “yes” if it is true, “no” if it is false.

1. The pharynx is part of the digestive tract.
2. The gastric mucosa contains a large number of glands that secrete intestinal juice.
3. In the pharynx, the digestive tract intersects with the respiratory tract.
4. In the oral cavity, food is subjected to mechanical processing, wetting and disinfection.
5. The initial section of the intestine is called the duodenum.
6. The appendix is ​​a vermiform appendix of the rectum, when inflamed, the disease appendicitis develops.
7. In the oral cavity there are tonsils that perform a protective function.
8. Bile is produced in the pancreas.
9. The epiglottis closes the entrance to the larynx during swallowing.

4. Homework

1. Draw up a more complete structural and logical diagram, prepare an oral detailed answer.

2. Complete the practical work “Location of the salivary glands” (page 125 of the textbook).

1. Prepare reports on dental diseases or electronic presentation.