The role of the skin in thermoregulation of the body abstract. Summary of the lesson on the topic “The role of the skin in the thermoregulation of the body Damage to the skin
Lesson topic: The role of the skin in thermoregulation.
Target: to form the concept of "thermoregulation".
Tasks: 1. To reveal the role of the skin in the regulation of body temperature.
2. Learn the rules of first aid in violation of thermoregulation.
3. Be able to use personal experience in establishing the dependence of heat transfer on environmental conditions.
4. Develop the skills of independent work with the text of the textbook to obtain the necessary information.
Lesson plan: 1. Organizational moment.
2. Statement of the problem situation.
3. "Opening" the topic of the lesson, setting the goal and objectives of the lesson.
4. Experiment.
5. Test survey.
6. Learning new material.
7. Fixing.
During the classes.
Slide number 1. Questions: 1) By what principle are these animals divided into two groups?
2) Which of these groups does the person belong to?
Slide number 2. Now imagine that we are in 15th century Italy. In the magnificent castle of the Milanese Duke Moro, a magnificent holiday is taking place, the idea of which was invented by the great Leonardo da Vinci. The "golden age" of the Renaissance personifies a little boy, whose body was completely covered with golden paint. After the holiday, everyone forgot about him. And only the next day, Leonardo da Vinci found the baby in a dark corner of a cold room. He was crying and shivering from the cold. A few days later the boy died.
Question: What is the reason for the death of the "golden boy"?
The versions that the guys offer can be written on the board.
Teacher: You see that so far you do not have enough knowledge to give the correct answer to the question.
Together with the students, the topic of the lesson, the goal, and the tasks are formulated.
Slide number 3.
Experiment. The guys are invited to measure the temperature of different parts of the body (palm, hand, face, armpit), the data is recorded on the board. While 3-4 people are doing the experiment, the rest are doing a test on the topic "The structure and functions of the skin."
Analysis of the results of the experiment, formulation of conclusions. 1) Different parts of the body have different temperatures. 2) 36.6°C - the average temperature of the human body. 3) 25°С>lethal>43°С.
Learning new material.
In the human body in 1 hour, as much heat is generated as needed to boil 1 liter of ice water. During heavy physical work, heat generation increases several times. And yet the body temperature does not change. Why? (Discussion of the problem by students).
The constancy of body temperature is maintained by regulating the release of heat from the body. And this role belongs to our skin, since this organ is in direct contact with the external environment and, therefore, registers changes in its temperature.
Slide number 4. Working with the scheme.
A message about the methods of heat transfer by the body can be given in advance or you can offer strong students to work with the article while the rest are doing the test and experiment. The death of the "golden boy" is discussed again, the reason is established. More than 200 years ago, the English doctor Ch. Blegden conducted an experiment: together with several friends, he spent 35 minutes in a dry chamber at a temperature of + 126 ° C without health consequences. At the same time, a piece of meat taken into the chamber turned out to be cooked, and cold water boiled under a layer of oil.
Application: analyze the data and determine the dependence of heat transfer on environmental conditions. Fill the table.
Slide number 5. The correctness of the task is checked.
Independent work with the textbook. Task: fill in the table "First aid in violation of thermoregulation".
Consolidation.
Questions to test knowledge at the mandatory level:
What is the role of the skin in thermoregulation?
How to prevent heat and sunstroke?
What is the danger of a significant burn of the body?
Questions to test knowledge at an advanced level:
Why is heat easier to bear in a dry desert than in a tropical rainforest?
What should be summer and winter clothes?
Why is it unacceptable to use alcoholic beverages to "warm up" with hypothermia?
Homework.
Test on the topic "The structure and functions of the skin"
1. The skin protects the deeper organs and tissues from damage, as it ...
A) strong and resilient
B) maintains the constancy of the internal environment of the body
B) waterproof
D) contains many receptors
2. The skin protects the body from ultraviolet rays, as it ...
A) lots of fibers
B) there is subcutaneous fat
B) have receptors
D) vitamin D is produced
3. The epidermis is located ...
A) on the surface of the skin
B) under the skin
B) on the surface of the subcutaneous adipose tissue
D) subcutaneous fat
4. Actually the skin ...
A) form keratinized cells
B) gives skin elasticity
B) blocks ultraviolet rays
D) does not pass liquids and gases
5. Fat is excreted...
A) sweat glands
B) sebaceous glands
B) receptors
D) lymphatic vessels
Biology and Economics Teacher
MSOS №1
Named after M.A. Pogodin
Polyarny city
Kotelnikova Ya.A.
Topic: " The role of the skin in the body's thermoregulation Damage to the skin"
WordsLebedev-Kumach V.
temper yourself
If you want to be healthy
try hard
Forget about the doctors
Pour cold water
If you want to be healthy!
It's more useful for us
sun, air and water
From diseases
Help us always
From all diseases it is more useful for us
Sun air and water!
temper yourself
If you want to be healthy
try
Forget about the doctors
Pour cold water
If you want to be healthy!
Lesson type: learning new material (according to the didactic purpose), combined (according to the methods of organizing activities).
The purpose of the lesson:
educational- to concretize knowledge about the structure of the skin;
- to form knowledge about the skin as an organ of heat transfer;
Thermoregulation with increasing and decreasing temperatures
developing- continue to develop the ability to work independently with a textbook, drawings in a workbook for the textbook “Biology. Human." author N.I. Sonin and use their data to draw up charts, tables and answer questions;
- develop the ability to establish a relationship between non-compliance with hygiene rules and the development of skin diseases;
To develop the ability to establish the relationship between hardening and human health;
- to develop the ability to establish the relationship between physical work and thermoregulation of the body;
Develop skills to provide first aid for overheating, frostbite and skin burns.
General Skills: work with a textbook and additional literature, analyze and compare information, summarize and establish cause-and-effect relationships, make tables.
Special skills: solve biological problems, work with computer drawings and diagrams related to the structure of the human body.
Lesson objectives:
To get acquainted with the role of the skin as a heat transfer organ.
Explain the conditions for maintaining a constant body temperature.
Uncover the secrets of thermoregulation.
To get acquainted with the reasons for the increase in body temperature in diseases.
To reveal the relationship between hardening and human health.
Learn to provide first aid for overheating, frostbite and skin burns.
Preliminary preparation of the teacher:
— to develop a presentation on the topic "The structure of the skin."
Develop a presentation on the topic “The role of the skin in the thermoregulation of the body. Damage to the skin";
Create task cards for group work
Select biological tasks on this topic.
Preliminary preparation of students:
Find additional literature on the topic under study.
During the classes
Stage 1 - Organizational - absent in the class are noted, the topic of the previous lesson is recalled, goals are set for this lesson, the distribution of students into groups.
Hello, who is missing from the class. It is not for nothing that today our lesson begins with a song performed by Leonid Utyosov, because today we will talk about health in the lesson. Today we will need to find out what role the skin plays in the thermoregulation of the body and what are the damage to the skin. But at the beginning of the lesson, we will recall the material of the previous one.
2-3 MINUTES FOR THE FIRST STAGE
Stage 2 - Control of knowledge on the topic of the last lesson:
And so, who can recall the topic of our last lesson? (Skin structure) Today, at the beginning of the lesson, we will recall the material of the past, which in turn will allow us to move on to the study of new material. And without the necessary level of knowledge on the studied material, it will be difficult to study a new topic.
Testing students' knowledge of the structure of the skin and nails. To perform this work, the student sits at the teacher's table, where a computer with a multimedia system is located. A previously prepared slide with the structure of the skin is already displayed on the screen. The student only needs to choose one of several answers. At the moment when one student works with the test, another (more capable) student named by the teacher talks about the structure and functions of the skin. A little later, after checking the homework, in the oral form of the first student, the second one analyzes his answer (test), and only at this moment the test is displayed on the screen using the multimedia system.
Questions for written work on the first desk - cards with test tasks are issued. For this work, two students are called, the time for their work is negotiated - while the oral test is in progress, no more.
Question for the first student:
Tell us what layers the skin consists of and about their functions in our body. When responding, skin layers must be signed using a computer program.
Question for the second student:
Tell us about the functions of the sweat and sebaceous glands and about the structure of the hair and nails. When answering, the structure of the nail must be signed using a computer program.
After checking the homework, the teacher evaluates the students.
10 MINUTES ARE ALLOWED FOR THE ENTIRE KNOWLEDGE CONTROL.
Knowledge update Teacher “In our last lesson, we studied the structure and functions of the skin. And today in the lesson we need to find out what role the skin plays in the thermoregulation of the body. And is it really necessary for our body?
Stage 3 - Problem Statement - At the end of the lesson, I want to hear the answer to the question: “What role does the skin play in the health of the body.
Stage 4 - Studying new material - studying in groups the role of the skin in the process of thermoregulation, familiarizing the class with the results of the group's work.
To study new material, you are divided into groups, each of the groups faces certain tasks that are written on your cards. To solve your problems, you can use the textbook and books lying on your tables. We'll start talking in 10 minutes.
Questions for the first group:
If all organs emit heat, then why hasn't a person burned out yet?
Why overheating of the body can occur and what first aid should be given to a person – MESSAGE.
Why is hardening so useful for the human body? What hardening methods do you know.
Questions of the second group:
How is a constant body temperature achieved?
START THE PRESENTATION AFTER CONFIRMING THE STUDENT'S ANSWER.
PRESENTATION FROM THE DISC 8kl.
PRESENTATION from disk8kl THERMAL REGULATION IN PHYSICAL WORK.
Why freezing and frostbite of the body can occur and what first aid should be given to a person - MESSAGE.
Why is hardening so useful for the human body? What hardening methods do you know
Questions of the third group:
Why does the body temperature rise in diseases and why should it be lowered?
As a result, solar, thermal and chemical burns can occur in humans and what first aid should be provided– MESSAGE.
3. Why is hardening so useful for the human body? What hardening methods do you know.
The material is shown through the multimedia system - receptors of the skin, the processes taking place in the skin with an increase and decrease in temperature are shown, schemes are shown about hardening, frostbite ..., ALL MATERIAL IS SHOWN AT THE TIME OF THE CHILDREN'S PERFORMANCE.
Topics for children's messages (the topics were given in the previous lesson):
Solar, thermal, chemical burns and first aid.
General freezing of the human body, frostbite and first aid.
Overheating of the body and first aid(Degrees of overheating of the body . Slight overheating of the body First aid for mild overheating of the body. Heat and sunstroke First aid for heat and sunstroke).
hardening .
For a more complete understanding of the role of the skin in our body, let's analyze the laboratory work that you did at home for two weeks and do one work in class.
10 MINUTES ARE ALLOWED FOR THE FOURTH STAGE.
Stage 5 - Consolidation and primary testing of knowledge - a test on the topic.
And so we solved all the necessary tasks by studying a new topic. But now, to consolidate the material, we will perform oral laboratory work using a multimedia system. As you complete your work, you can earn grades.
The test is displayed using the multimedia system on the screen. A student is called to test, but to attract the attention of the whole class, the teacher reads the test questions aloud. And this, in turn, allows children to systematize knowledge on the material covered and perhaps even better remember it. Since at this moment both visual and auditory memory are turned on in children. The test is taken from the disk 1C: School. Biology, 8th class. Man. When solving the test, if the student makes a mistake, then he does not proceed to the next question, and this, in turn, allows you to once again draw the children's attention to the material being studied.
10 MINUTES ARE ALLOWED FOR THE FIFTH STAGE.
Stage 6 - Summing up.
Estimates are given and commented on by all children speaking at the lesson. With good preparation of children for the lesson and the correct distribution of time, the teacher will be able to grade more than 60% of the class in the lesson. At the end of the lesson, for verification, children's workbooks with completed laboratory work are also collected.
And so today at the lesson we studied the topic: "The role of the skin in the body's thermoregulation. Damage to the skin."
And I would like to hear the answer to the question posed at the beginning of the lesson: “What role does the skin play in the thermoregulation of the body (in the health of the body)?” ...
The skin is the thermoregulatory organ of our body. And thermoregulation itself is carried out due to a change in the lumen of blood vessels and sweating. And if we carry out the processes of hardening our body correctly, we will get sick less and live longer.
Stage 8 - Homework.
For the next lesson, I ask you to learn the material from pp. 178-179.
Orally answer the questions p.180.
In the next lesson we will talk about skin care. Hygiene of clothes and shoes. As well as skin diseases. All of you who are interested can prepare reports on skin diseases. I ask you to pay special attention to ringworm and scabies.
Lesson summary
:
Today we got acquainted with the role of the skin in the thermoregulation of the body. You, I hope, have concluded that external beauty does not guarantee health. Health is the most important thing. And remember that a healthy mind in a healthy body .
Thank you, you all did a great job today and deserved a high score.
Skin layers Structure
2) the inner layer of the fabric;
The stratum corneum is the least developed
Hair roots are surrounded by:
IV. Write the correct word.
V. The dermis of the skin originates from:
VI. The skin performs a protective function, as it contains:
VII. The dermis is made up of cells:
D) capable of division;
Test for the lesson "Skin as an organ of thermoregulation"
I. The stratum corneum is the least developed
A) feet B) centuries; B) palms D) knees.
Hair roots are surrounded by:
A) adipose tissue B) epidermis;
B) capillaries; D) a special bag.
Specify the correspondence between the layers of the skin and their structure.
Skin layers Structure
1) the outer layer A) is represented by bundles of connective
(cuticle) tissue fibers and fatty
cells of the loose connective tissue
2) the inner layer of the fabric;
The skin itself (dermis) B) is represented by connective tissue and elastic fibers, smooth muscle tissue;
3) subcutaneous fat B) is represented by stratified epithelial cells;
D) represented by cells of a single-layer epithelium;
IV. Write the correct word.
The skin itself is made up of _____________ tissue rich in intertwining elastic fibers.
V. The skin performs a protective function, as it contains:
A) receptors; B) pigment melanin; B) sebaceous glands D) epidermis;
VI. The dermis is made up of cells:
A) orgovevshie and constantly sloughing off;
B) forming a pigment on which the color of the skin depends;
D) capable of division;
VII. The dermis of the skin originates from:
A) ectodermal; B) endodermal;
B) mesodermal; D) mixed;
Tasks: Generalize knowledge about the protection of the body from overheating and hypothermia, introduce the conditions for maintaining a constant temperature of the human body, methods of thermoregulation, with its reflex mechanisms, achieve the assimilation of knowledge about the symptoms of overheating, burns, frostbite, first aid measures when they appear.
Equipment: Presentation for the lesson on Microsoft PowerPoint “Thermoregulation of the human body”, multimedia projector, screen, computer, didactic table “Heat generation and loss”
During the classes
1. Updating knowledge about the structure and functions of the skin.
Biological dictation by options.
Option 1.
- deepest layer of skin subcutaneous tissue.
- 95% of germs on the hand are under the nails .
- The sweat glands perform excretory function.
- The subcutaneous tissue is formed fatty cloth.
- The hair is in the hair bag.
Option 2.
- The outer layer of the skin epidermis.
- Vitamin is produced in the skin D.
- The sensitivity of the skin is carried out with the help of receptors.
- skin glands: sweat and sebaceous.
- Skin pollution makes work difficult sweat glands.
2. Learning new material
2.1. Introduction to the topic, tasks and lesson plan. Write the topic in a notebook. (Presentation.) (Slide 1)
Teacher: The regulation of body temperature is extremely important in conditions of rest and a variety of human activities. As a result of the continuous decomposition of substances in the body, thermal energy is released. Blood vessels permeate the body, reaching the muscles, liver, and other organs where heat is generated. The blood in these organs heats up and then gives off some of its heat. The average body temperature of a person is about 37 C. The average body temperature fluctuates throughout the day.
2.2.
Teacher: The slides show examples of human activities. How does the amount of released energy and body temperature fluctuate? (Slides 2-3)
The dependence of body temperature on the type of activity.
Students' conclusions: The amount of thermal energy depends on the intensity of metabolism. In a calm state, heat is generated in small quantities. Heat generation is enhanced by muscular work.
2.2. Physiology of thermoregulation. (Conversation on questions using the didactic table “Heat generation and loss”.)
Student: Muscles and liver.
Teacher: What process releases energy?
Student: Due to the breakdown of proteins, fats, carbohydrates.
Teacher: Hence, the formation of energy can be called the chemical side of thermoregulation. What organs are involved in heat loss? (Slide 4)
Student: Skin, lungs, excretory system, digestive tract
Teacher: Is heat loss also a chemical process?
Student: No, physical.
Teacher: (Slides 5-6) Which of these conditions:
Answer options:
- Dry air.
- Skin pollution.
- Moist air (above body temperature)
- High air temperature.
- Low air temperature (below body temperature).
- Clear skin.
Teacher: Based on thermal phenomena, we conclude that there are only three ways of heat transfer: evaporation, heat conduction, radiation. Try to solve more difficult problems.
Why do people drink more in hot weather?
Student: To enhance evaporation, since during evaporation a person loses a lot of thermal energy.
Teacher: Why is it suggested to throw a damp sheet over the body in hot weather?
Student: To enhance heat conduction.
Teacher: Why is it hard to endure both heat and cold in wet weather?
Student: In hot weather, evaporation becomes more difficult; in cold weather, heat conduction and radiation increase.
Teacher: Why is it that in a Finnish bath-sauna, where 100 degree dry air, a person endures painlessly, and bathing in 100 degree water is life-threatening?
Student: In dry heat, evaporation and getting rid of heat easily occur, and in 100-degree water, the body's heat transfer stops, overheating begins due to heat conduction.
2.3 Violations of thermoregulation and first aid for them. The teacher's story about violations of heat transfer: heat and sunstroke, burns and frostbite and first aid to victims. (Slides 7-13).
Independent work of students in notebooks to fill out the table. (Slide 14)
The work goes in groups, with a discussion of the material and filling in the table.
3. Consolidation of the material covered. Conversation on:
- How is heat transfer regulated by the body?
- What disruption hinders heat transfer?
4. Homework.
Page 178–179 of the textbook to study, answer the questions on page 180.
Target:
1. to form students' knowledge about the functions of the skin associated with the regulation of the constancy of the internal environment of the body, using knowledge of biology and physics for this.
2. consolidate knowledge about the structure of the skin, with its basic properties; to form the need to protect one's health;
3. to draw the attention of the child to himself, to his own structure through experience, to come to scientific knowledge, to lead to an understanding of himself as a person.
Lesson objectives:
educational:
1) specify knowledge about the structure of the skin;
2) to form knowledge about the skin as a heat transfer organ;
3) To reveal the conditions for maintaining a constant body temperature with an increase and decrease in temperature.
developing:
1) develop the ability to draw conclusions from the results of practical work;
2) to develop the ability to establish the relationship between physical work and thermoregulation of the body;
3) develop the ability to analyze and compare information, summarize and establish cause-and-effect relationships.
educational:
1) to continue the hygienic education of students, respect for their health,
2) develop communication skills.
Equipment:
1. projector
2. presentation
3. laptop Nova 5000
4. temperature sensors
5. humidity sensor
6. thick thread
7. plastic bag
8. rubber ring
During the classes
1. organizational moment
2. Actualization of basic knowledge: Very often, letters from readers are published in youth newspapers and magazines, listen to an excerpt from such a “letter”. Does it contain biological errors and inaccuracies? What are they?
Finally, the long-awaited time has begun - the holidays! My friend and I woke up at noon and immediately ran to the beach. Get into the water! Having bathed to the point of exhaustion, they stretched out on the sand and sunbathed for three hours. I taught in a biology lesson that ultraviolet rays increase the stratum corneum of the skin, a pigment gradually accumulates in its cells, giving it a brown color - a tan. This is beauty and health.
3. Learning new material:
look at the slide and determine which two groups the animals depicted here can be divided into. What is the basis for the division into groups? (slide 1)
Which of these groups does the person belong to?
What property of an organism is called warm-bloodedness? (Warm-bloodedness is the property of the body to maintain body temperature at a certain level.) (slide 2)
“And now guys, I want to tell you one legend (pleasant music sounds). (slide 3)
Almost five centuries ago, in the last days of 1496, in the luxurious castle of the Milanese Duke Moreau, they were preparing for the New Year's holiday. The duke was going to show his guests such wonderful performances as the world had never seen before. Still would! The organization of the holiday was led by the great artist and unsurpassed mechanic Leonardo da Vinci. He planned to glorify the golden age of the world, which came after many years of the Iron Age of devastating wars.
To depict the Iron Age, the blacksmiths, under the supervision of Leonardo da Vinci, made a huge figure of a lying knight, clad in armor. And the golden age was supposed to depict a naked boy, covered from head to toe with golden paint. It was the son of a poor baker. His father, for money, provided him for the amusement of the duke.
In the midst of the festive fun, a defeated knight was brought into the hall. From his womb emerged a "golden boy" with wings and a laurel branch in his hand. Frightened, he looked at those around him, uttering a learned greeting to the duke. The holiday could not be completed, because the duke's wife suddenly fell ill. The guests have departed. The lights went out. Of course, they forgot about the boy ... He was left alone, in a huge, cold, dimly lit room. Only the next day Leonardo da Vinci saw him in a dark corner. The child was trembling and crying piteously. Leonardo wrapped him in a cloak, took him to his home and looked after him for three days, trying to save him. But on the fourth day the boy died. Centuries have passed. The history of the "golden boy", associated with the name of the great artist, was not forgotten. And the cause of his death for a long time remained incomprehensible and caused different interpretations.
Can you answer me and name the main reasons for the death of the boy? (students formulate an answer and say that this boy died of hypothermia. The function of thermoregulation was impaired.)
Today we will talk about thermoregulation. Write down the topic of the lesson "Thermoregulation of the body" (slide 4)
From the point of view of physics, a person is just a physical body, and it would seem that processes should take place with him, the same as with any physical bodies. The human body temperature is 36.60C, and in the classroom - 240C. A person must give part of the internal energy to the surrounding air until the temperature becomes the same. But is it so?
What new things should we learn about this topic? Let's formulate the goals of our lesson (students formulate goals, and the teacher specifies them) (slide 5) Explain why our body temperature remains constant. To answer this question, we must remember the structure of the skin. (slide 6)
Do you know how much heat is generated in the human body in one hour? So much that is enough to boil 1 liter of ice water. And if the body, instead of the skin, was covered with a case impervious to heat, then in an hour the body temperature would rise by about 1.5 degrees, and in forty hours it would reach the boiling point of water. During hard physical work, heat generation increases several times more. (slide 7)
And yet the body temperature does not change. When talking about body temperature, they mean the temperature of the internal regions of the body, i.e. tissues lying deeper than 2.5 cm under the surface of the skin. In humans, the surface temperature of the skin is not the same in different areas. The lowest temperature is near the skin of the hands and feet (28.50C), and the highest is in the neck area. Inside the liver, where oxidative processes take place, the temperature reaches 390C. (slide 8)
In a healthy person, it is usually equal to 36.5-37 degrees. Its rise above 430 and fall below 250C are fatal. This constancy of body temperature is maintained almost exclusively by the regulation of heat transfer through the skin. After all, it is in direct contact with the external environment, therefore, it registers all changes in temperature.
The set of physiological reactions of the body that ensure the constancy of body temperature is called thermoregulation (slide 9)
When is heat produced in the body? (meal, muscle work) (slide 10)
What are the sources of heat in the human body? (Nutrients (proteins, fats, carbohydrates), which, when decomposed (hydrolysis with the participation of enzymes - biological catalysts), release heat (exothermic reactions occur), in addition, there are active tissues - the liver, muscles.)
In order for a body to give off heat to the environment, the heat generated by it must “have access” to the external environment. Heat from the depths of the body (core) is transported by blood to the skin, from where it can pass into the environment due to one of the following mechanisms: (slide 11)
1. Loss of heat through the skin by radiation
2. By convection
3. By conduction.
All of them depend on the amount of blood flowing through the skin.
But how it depends, we will check by conducting a laboratory work "Impaired blood circulation when applying a tourniquet." To carry it out, we will use the digital laboratory. You have all the necessary materials for its implementation and instructions on your tables (Appendix 1)
Why does the temperature of fingers insulated with a constriction decrease?
Why, after the restoration of normal blood supply, the temperature of the fingers slightly increases compared to the initial one?
Human skin is abundantly supplied with blood vessels. Many capillaries form loops and anastomoses to change the amount of blood flowing through the skin capillaries. When these vessels narrow, heat transfer decreases. As they expand, heat generation increases. In addition, a large amount of blood flows through the sweat glands. (slide 12)
Now try to explain Dr. C. Blagden's experience in England over 200 years ago. Together with several friends and a dog, I spent 45 minutes in a dry chamber at a temperature of +126 without health consequences. At the same time, a piece of meat taken into the chamber turned out to be cooked, and cold water, the evaporation of which was prevented by a layer of oil, was heated to a boil. (slide 13)
During evaporation, heat is lost from the surface of the body in the process of turning water into water vapor. The evaporation of 1g of water takes 2.45 kJ of heat. Heat transfer by evaporation of sweat occurs continuously in the form of sweat imperceptible to us.
Sweat is a watery liquid containing 0.1-0.4% sodium chloride, sodium lactate and urea. It is formed from tissue fluid. (slide 14)
In humans, sweating begins when the temperature rises above 36.70C. Under normal conditions, 900 ml is released per day, but with very strong heat and a sufficient supply of water and salts, this value can reach 12 liters.
Now you will conduct another laboratory work "Excretory and thermoregulatory function of the skin" after which you will answer the following questions:
1. Why does the temperature in the bag rise during the experiment?
2. Why does the moisture in the bag increase?
3. Why in the second experiment, the humidity increased faster and reached a higher value than in the first experiment?
4. Why are summer clothes made from natural and not synthetic fabrics? (slide 15)
And now let's try to formulate the main conclusions of this lesson.
1) The skin is the main organ of thermoregulation
2) Depending on the nature of the implementation of thermoregulatory mechanisms, warm-blooded and cold-blooded animals are distinguished
3) Thermoregulation is the process of balancing heat generation and heat transfer in accordance with the conditions of the external and internal environment
4) Violation of thermoregulation processes can lead to overheating or hypothermia of the body. (slide 16)
The formation and release of heat is regulated reflexively and humorally. There is a thermoregulatory center located in the hypothalamus (midbrain). It is believed that in its anterior part there are centers that regulate heat transfer, and in the area of \u200b\u200bthe posterior hypothalamus there are centers that control the processes of production and preservation of heat. (slide 17)
The ambient temperature and its fluctuations act on the thermoreceptors of the skin. It is estimated that there are 12 cold, 1-2 heat receptors per 1 cm2. And the entire skin surface of the human body contains 250 thousand cold receptors and only 30 thousand thermal ones.
4. Consolidation of the studied material:. (slide 18 - 21)
Solve biological problems:
- The effect of alcohol on the body causes vasodilation. What kind of person, sober or drunk, will freeze faster in the cold?
- Feet in tight shoes freeze in winter and get very hot in summer. Explain why?
- Why is it harmful to tighten the belt tight and wear tight shoes?
- A person in a temperate climate wears clothing appropriate to the weather. However, the inhabitants of Central Asia in the hottest weather wear warm wadded robes. Give an explanation for this phenomenon.
§42
Compose a cinquain on the theme "Skin"
Let's try to figure out how a constant temperature of 36.6 C is maintained in the human body?
And yet the body temperature does not change. Why do you think? And, here, I wonder why our body temperature remains constant? Some processes take place in the human body.
Now we will try to explain the mechanism of generation and release of heat. Let's work with the diagram.
Task number 1. Analyze and explain the diagram.
Diagram conversation. There is a table in front of you. When you eat hot food, your body becomes warm. And when?
To do this, I suggest you complete the table.
Task number 2. Fill in the table "Regulation of heat transfer by blood vessels." Valeological pause (music)
Task number 3 . BUT Also, what conditions favor heat regulation? Properly selected clothes for the seasons of the year, depending on the ambient temperature and quality.
Let's do a simple experiment: take glass rods, dip them in water and touch them to the skin of your hand, what did you feel?
Task №4 Problem situation from everyday life.
On a sunny summer day, Masha played with her friends on the beach for a long time. When she returned home, she had a fever, felt a headache and was very thirsty. Grandmother thought that her granddaughter had caught a cold, gave her tea, wrapped her in a blanket. But Masha did not get better. The doctor who arrived on call for some reason scolded the grandmother for her actions. Why do you think?
What happened to the girl? (got sunstroke)
What was wrong with grandma? (wrong first aid)
What measures should be taken in case of heat and sunstroke?
Conclusion: The increase in body temperature depends on the ambient temperature, and we must know the rules for first aid for heat and sunstroke.
And now, guys, let's work in groups and solve biological problems. 1 group: The effect of alcohol on the body causes vasodilation. Which person, sober or drunk, will freeze faster in the cold? Warm blood warms the skin. Thermal receptors produce a feeling of warmth. The vessels of the deep layers of the skin are enlarged and the person loses the last heat. Expansion or constriction of blood vessels creates a feeling of warmth. The release of excess heat occurs in the vessels of the skin, which can accommodate 30% of the entire blood of the body.
2 group:
The development of a feverish state is often accompanied by trembling and a feeling of coldness (chills). Explain these symptoms based on the idea of the thermoregulation mechanism (water evaporates, the body cools down). Chills are muscle contractions. When the muscles contract, the blood vessels constrict, the temperature builds up. It is the body's defense to fight infection.
Conclusion: Thus, thermoregulation occurs due to the vessels of the skin, sweat glands, and the nervous system.
And now we solve the test individually, consisting of 6 questions. Evaluation criteria: 6 points - "5",
5 points - "4", 4 - 3 points - "3", 1-0 points - "2".
Let's take a look at the issue with you:
Task number 6. Why do some people, being outside at low temperatures, quickly freeze and catch a cold, and others are in the cold for a long time and do not get sick?
Yes, indeed, hardening is one of the ways to strengthen and maintain health. .
What is the motto of hardening? Motto: "The sun, air and water are our best friends!"
Optional comment on homework.
Page 168-170 textbook, answer questions 1-4 orally
- Draw up a memo "Tempering rules of 5 points"
