"The Importance of Internal Environment Steady-state" is the content of section 2 of chapter 1 of biology compulsory module 3 in senior high school standard experimental textbook (PEP). It is the further extension and expansion of the first section, and it is also the basis of learning the adjustment of life activities, which has the function of connecting the preceding with the following.
Steady state is an important core concept of compulsory module 3. Handling the teaching of this concept well can lay a solid foundation for the follow-up study. Therefore, the concept and importance of steady state is the focus of this teaching content. The regulation mechanism of steady state should be gradually developed and deepened in the study of later chapters. In this section, we only make a brief overview to prepare for the following courses.
Human health is closely related to internal environment homeostasis. Almost everyone has experienced diseases caused by internal balance, such as fever and diarrhea. Therefore, students can understand the essence of life activities and establish the concept of healthy life in combination with real life by learning the steady content of internal environment.
Second, the establishment of teaching objectives
1. Knowledge target
(1) Summarize what is homeostasis and explain its physiological significance;
(2) Briefly describe the regulation mechanism of steady state.
2. Ability objectives
(1) "Mechanism of maintaining pH stability in living organisms" experimental operation;
(2) Try to explain the mechanism of maintaining pH homeostasis.
3. Emotion and values goals
(1) Pay attention to the relationship between the steady state of human internal environment and human health;
(2) It is of positive significance to identify with a positive attitude towards life and a healthy lifestyle to maintain the internal environment.
Third, the handling of teaching priorities and difficulties
1. Teaching focus
The concept of (1) environmental homeostasis.
(2) The significance of internal environment homeostasis.
2. Teaching difficulties
Experimental operation on the mechanism of maintaining pH stability in organisms
Fourth, the specific teaching plan and implementation process
Organization and guidance of teachers
Student activities
Design intent
Remind students to get ready for study.
Play the video: "About uremia".
Ask questions:
According to the video, please think about it. What is the biggest change in the composition of internal environment between uremia patients and healthy people?
Course evaluation:
Uremic patients are damaged by the accumulation of metabolic wastes and toxins, which is life-threatening. It can be seen that maintaining the relative stability of the internal environment is of great significance to the body.
Let's walk into today's class together.
Writing on the blackboard: the importance of environmental stability in the second quarter
Ask questions:
So, what is the homeostasis of the internal environment? Below we will understand the concept of internal environment homeostasis through discussion of problems.
Blackboard writing:
First, the cognitive method of the concept of steady state
The human body is engaged in life activities all the time, and the external environment is fluctuating, so will our internal environment change greatly?
PPT demonstration:
Discussion 1: Dynamic changes of internal environment
Table 1: Dynamic change of environmental component content
project
estimated value
unit
reference range
Alanine aminotransferase
Mid-tenor
17
International unit/liter
0~45
creatinine
creatinine
0.7
Mg/dl
0.5~ 1.5
urea nitrogen
Serum urea nitrogen
14.6
Mg/dl
6~23
Serum glucose
GLU
223
Mg/dl
60~ 1 10
Triglyceride
TG↑
2 17
Mg/dl
50~200
Total cholesterol
Total cholesterol
179
Mg/dl
150~220
Ask questions and arrange discussions:
1. The reference value (normal value) of each component has a range of variation. What does this mean?
2. From the inspection list, which components are beyond the normal range? What adverse effects may this have on the human body?
Brief evaluation, supplement and form * * * knowledge:
(1. The contents of various components in the internal environment are not constant, but are in dynamic change. )
(2) Too high glucose content may cause diabetes, and may also be complicated with ketoacidosis; Too much triglyceride can cause hyperlipidemia, coronary heart disease and atherosclerosis. )
PPT demonstration:
Question 2: Variation characteristics of internal environment pH.
Ask students:
After strenuous exercise, why do muscles ache?
After the lactic acid produced enters the blood, will it cause a significant decrease in the pH value of the internal environment?
It leads to the experimental question: the mechanism of maintaining pH stability in organisms.
PPT presentation: textbook P.9- 10 Experiment
Organize students to conduct experimental research in groups;
Let's discuss the influence of acid and alkali on the pH value of the internal environment through experiments.
Remind students to pay attention to the experimental procedures, including:
① Correct use of experimental materials and instruments; (2) the sequence of the experimental process; ③ Friendly cooperation among students.
Go deep into students' experimental activities and give appropriate guidance and counseling. Adjust the process of students' experimental activities.
Arrange students to report the experimental results in groups, and organize brief analysis and discussion.
Analyze and discuss with students, encourage them constantly, and arouse students' doubts.
Make a summative evaluation and draw an experimental conclusion.
Animal plasma contains buffering substances, which have a certain buffering effect on acid and alkali, so that the plasma pH is in a dynamic balance.
PPT demonstration: In normal people, the pH value of the internal environment is in dynamic balance.
PPT demonstration:
Question 3: Variation characteristics of body temperature.
Show the investigation report of "daily variation law of body temperature"
time
six o'clock
nine?o'clock
12:00
15:00
18:00
2 1:00
Before going to bed
average temperature
environment
temperature
mother
father
oneself
Arrange students to present the preliminary report of the pre-class investigation in groups.
Ask questions for discussion and arrange students to discuss in groups:
1. What are the characteristics of the temperature change of the same person within 24 hours?
2. Has the body temperature been around 37℃?
3. Compare the measured value of body temperature change with the measured value of daily temperature change of the day. What is the result?
Evaluation and summary:
The body temperature of healthy people also remains relatively stable.
PPT demonstration:
Question 4: Variation characteristics of osmotic pressure in internal environment.
Ask students:
If you need to use normal saline when you are sick, can you tell us the concentration of normal saline?
PPT Presentation: "Erythrocyte Morphology Map"
Questioner: Please predict what effect the concentration of Nacl solution is too low (hypotonic solution) or too high (hypertonic solution) will have on the morphology and structure of red blood cells during infusion.
Organize students to evaluate and affirm each other;
Under normal circumstances, the osmotic pressure of the human body's internal environment is relatively stable.
Teachers and students summed up the concept of steady state:
Through the above problems, it can be explained that every component and physical and chemical properties of the internal environment of a healthy human body are in dynamic balance. That is, the internal environment remains relatively stable.
So, why can the internal environment of a normal body remain relatively stable? What is the basis for maintaining a relatively stable internal environment?
Blackboard writing:
Second, the internal environment maintains a relatively stable material basis and regulation mechanism.
PPT animation demonstration:
Give students a brief understanding of the regulation process of plasma pH.
According to the textbook chart 1-4, help students get familiar with the related organs and systems in the human body.
Ask questions, arrange for students to read textbooks and contact the answers themselves.
1. Which organs are directly involved according to the process of plasma pH adjustment? What systems are directly involved?
2. Do these organs and systems participate in or coordinate activities at will through the pH regulation process?
3. Why can all the organ systems of the body maintain harmony?
Inspire students to think and arrange them to read the last two paragraphs of the textbook p.8.
How has human's understanding of the mechanism of maintaining relative stability in the internal environment been gradually improved?
Teachers and students * * * are clear respectively: (PPT presentation)
From Bernard's conjecture (mainly relying on the regulation of nervous system) to Cannon's explanation (in the co-regulation of nerve and body fluid), and then to the modern point of view: the main regulation mechanism is the function of "nerve-body fluid-immune regulation network"
Familiar with the concept of steady state again (integrating the concept points in the textbook);
The steady state of the human body refers to the function of the normal body through the neural-humoral-immune regulation network, which makes all organs and systems coordinate their activities and maintain a relatively stable internal environment.
Put forward the question of continuing thinking:
Since the internal balance is maintained under such a perfect regulatory mechanism as nerve-body fluid-immunity, does that mean that the internal balance of the internal environment will not be unbalanced?
Inspire students to pay attention to their own life experiences and discuss problems.
For example, during military training, the ambient temperature lasts as high as 39℃, and some students in the class suffer from heatstroke. ...
Another example: the islet B cells and their self-regulation function in diabetic patients are damaged, which leads to the increase of blood sugar concentration of environmental components.
Brief summary:
Through these phenomena, it is fully explained that the disorder of steady state brings diseases and then affects human health. It can be seen that it is of great significance to maintain the stable state of the internal environment.
Blackboard writing:
Third, the significance of internal environment homeostasis
Think with the phenomenon of students' contact with life, and discuss with teachers and students;
Phenomenon 1: a preliminary study on the experience and causes of fever, thinking about related problems from the perspective of enzyme reaction: why are there symptoms such as loss of appetite and weakness? What other factors affect the activity of enzyme?
Phenomenon 2: A classmate fainted due to hypoglycemia in the fifth class in the morning and was sent to the infirmary. The doctor immediately injected Liu Xin with glucose solution intravenously, and he soon woke up. What does this fact mean?
Phenomenon 3: People living in plain areas will have symptoms such as headache, fatigue, rapid heartbeat and even elevated blood pressure when they first arrive at the Qinghai-Tibet Plateau. What caused this? (The oxygen partial pressure in the atmosphere is low, which leads to human hypoxia ...)
Teachers and students * * * come to the conclusion:
The maintenance of internal environment homeostasis is a necessary condition for normal life activities.
Classroom consolidation and practice:
Summary of knowledge points and exercises: (see PPT)
(Note: To determine the difficulty of exercises according to students' cognitive level, you can initially contact the college entrance examination questions to let students know the requirements of the college entrance examination. )
Class is over:
Just after class, the video "Uremia" was released. Patients rely on hemodialysis to maintain a stable internal environment and prolong life. But I hope we can all stay away from unstable diseases such as uremia.
Arrange the content of extended study after class: (supplemented by PPT screen encouragement)
Consult the information, collect the diseases related to homeostasis and their preventive measures, and take the tabloid 1 issue with the theme of "homeostasis and health" as a group.
Teachers can collect the works of each group, hold exhibitions on campus, publicize the knowledge about health to the teachers and students of the whole school, and enhance people's health concept-life is more exciting because of health!
Observe and think.
Thinking and Answer: Metabolic wastes such as urea and uric acid are increasing.
Enter the learning state
Start thinking
Read the data in the table,
Compare and analyze the data item by item with the research group.
Group discussion, group communication
Self-evaluation and mutual evaluation
Enter a state of thinking
Experiment in groups,
Division of labor, cooperation and mutual communication.
Grouping experiment operation
The projector is used to display experimental data and graphics in groups, and the experimental results are analyzed and summarized, so as to achieve the purpose of understanding.
Act independently and take out the prepared study materials.
Show the results of pre-class survey with projector: investigation report on daily variation law of body temperature
Study in groups and exchange discussions. Panel report:
1. The temperature of the same person does not change much within 24 hours.
No! Only when people are healthy can their body temperature be around 37℃.
3. Ambient temperature has a certain influence on body temperature, but it has little influence.
Answer: 0.9% Nacl solution.
Observe and think.
Simple analysis answer:
Low concentration leads to the bursting of red blood cells; Excessive concentration will lead to dehydration and contraction of red blood cells.
Only when the osmotic pressure of the internal environment remains relatively stable can cells maintain their normal morphology.
Read the textbook P.8 and outline the concept points.
Contact yourself to know the names of related organs and systems.
Discuss with each other and form * * * knowledge:
The harmonious and normal operation of human organs and systems is the basis for maintaining a relatively stable internal environment.
Read independently and learn about relevant historical materials.
Answer: Steady state means that the normal body can coordinate the activities of various organs and systems through adjustment, and * * * maintain a relatively stable internal environment.
Complete the written integration of the concept of steady state in textbooks
Contact with the reality of life, express their opinions, and cooperate and communicate in groups;
The environment changes little, the internal environment fluctuates little, and it can still maintain a steady state; If the external environment changes too dramatically and exceeds its self-regulation ability, the steady state of the internal environment will also be destroyed.
Group communication forms * * * knowledge: the human body's ability to maintain steady state is limited.
Through cooperation and communication, it is concluded that normal body temperature and suitable pH are the basic conditions for the normal catalytic effect of enzymes in human body.
Sugar is the main energy substance of human body. Low blood sugar will lead to insufficient energy supply, resulting in hypoglycemia and other symptoms.
Complete the classroom test questions.
You can prepare in groups after class.
Create situations and introduce new lessons.
Motivate students
Advocate and guide students' autonomous learning.
Cultivate students' ability to obtain information and analyze data.
Demonstration and learning cooperative learning.
Strengthen the training of experimental operation skills
Cultivate students' ability to analyze experimental phenomena and draw experimental conclusions.
Guide students to pay attention to the compilation of investigation reports and learn to analyze data preliminarily.
Experience the joy of cooperative learning and success.
Think calmly, pay attention to observation and analysis
Teacher-student cooperation
Know yourself and learn to care for yourself.
Cultivate students' reading comprehension ability, so that students can further understand the core concepts in thinking and learn how to integrate knowledge initially.
Through the brief analysis of problems and cases, the understanding of concepts is sublimated.
Learn how to internalize knowledge again.
Timely feedback, and strive to improve the achievement of knowledge goals.
Cultivate students' ability of unity and cooperation and enhance the sense of collective honor.
Reflection on the Teaching of verb (abbreviation of verb)
This lesson is one of the topics of "201KLOC-0/Exhibition and Evaluation of Excellent Biology Courses in Senior High Schools in Sichuan Province". In order to embody the concept of the new curriculum, so that students at different levels can learn things in a relaxed and pleasant atmosphere, with the guidance and help of all the teachers in the teaching and research group, through the study and analysis of the teaching content of this topic and the brief investigation of the learning situation before class (for example, arranging students to complete the "temperature test" before class, and then I had a simple face-to-face conversation with the students in Nanxi No.1 Middle School, and adjusted the original teaching objectives and learning objectives moderately again.
Because one of the main features of this class is that it is very close to life, I choose to start with examples closely related to life and set up four questions to encourage and motivate students to study independently and participate in discussions and exchanges. Judging from the classroom learning atmosphere, students' thinking is quite active, and they actively participate in the learning process, especially the analysis and discussion of the body temperature survey report before each class is fierce and orderly.
Because the experiment-"the mechanism of biological maintaining pH stability" was inserted into the classroom teaching, and it was conducted in groups, the whole class could basically operate the experiment in an orderly manner according to the experimental requirements and get basically correct experimental results. In the process of analyzing the experimental results, I pay attention to fully mobilize students' active participation, report in groups, evaluate each other and enjoy the results, so that the learning atmosphere in the classroom has reached a climax.
Because this class not only pays more attention to the basic knowledge transfer exercises, but also consciously selects several extended exercises with certain depth, which obviously embodies the two aspects of teachers' "guidance" and students' "learning".
As it is the first time to try the teaching of new curriculum content, I pay special attention to consulting some teachers with practical teaching experience in different ways. When dealing with the difficulties in teaching, the implementation of teaching plans should give students some space and time to think, and the methods to break through the difficulties should be adjusted according to the situation and have various forms. For example, arrange students to complete the investigation report on the daily variation law of body temperature before class, and organize students to analyze the investigation results in class; Simple experiments are interspersed in the classroom to guide students to read and think about important sentences in textbooks, and to list some life experiences that students have experienced personally, so as to help students complete the complete understanding of the concept of "steady state" and the understanding of its meaning.
In the process of implementing the teaching plan, although there are sufficient preparations, there are also some obvious shortcomings. For example, in the design of teaching plans, we can also boldly deal with teaching materials and make full use of them as the most basic curriculum resources; There is also an overestimation of students' experimental operation ability, and individual students in the classroom have not got the expected experimental results. Therefore, it is more necessary to increase the preparation of pre-experiment before class, advocate mutual learning and teaching among students, and strengthen cooperation and communication.