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Knowledge points of biological environment steady state in senior high school
Senior high school biology learning skills
How to learn high school biology well
Knowledge points of biological environment steady state in senior high school
First, the internal environment is stable.
The chemical composition (moisture, inorganic salts, organic matter) and physical and chemical characteristics (osmotic pressure, pH, temperature) of the internal environment remain relatively stable.
Steady-state refers to a relatively stable state of the internal environment under the regulation of nervous system, body fluid and immune system through the coordinated activities of various organs and systems.
Second, the system involved in the internal environment homeostasis.
Systems directly involved in material exchange: respiratory system, digestive system, circulatory system and urinary system.
Regulation system: nervous system (neuromodulation), endocrine system (humoral regulation) and immune system (immunomodulation)
Third, the understanding of steady-state regulation mechanism.
1, French physiologist Bernard: Neuroregulation
2. American physiologist Cannon: Neurohumoral regulation
3. Modern viewpoint: Neurohumoral-immune regulation (as the main regulation mechanism of internal environment homeostasis)
In the process of metabolism, the human body will produce many acidic substances, such as lactic acid and carbonic acid. People's food (such as vegetables and fruits) often contains some alkaline substances (such as sodium carbonate). When these acidic and alkaline substances enter the blood, the pH of the blood will change.
Blood contains many substances that buffer pH value-buffer substances, and each pair of buffer substances is composed of a weak acid and a corresponding strong base salt, such as H2CO3/NaHCO3, NaH2PO4/Na2HPO4, etc. When the body is in strenuous exercise, a large amount of lactic acid, carbonic acid and other substances are produced in the muscles and enter the blood. After lactic acid enters the blood, it reacts with sodium bicarbonate in the blood to produce sodium lactate and carbonic acid. Carbonic acid is a weak acid, which can be decomposed into carbon dioxide and water, so it has little effect on the pH of blood. The increase of carbon dioxide in the blood will stimulate the nerve center that controls respiratory activities, promote respiratory movement, increase ventilation, and thus discharge carbon dioxide. After sodium carbonate enters the blood, it reacts with carbonic acid in the blood to generate bicarbonate, and excess bicarbonate can be excreted by the kidney. In this way, due to the regulating effect of buffering substances in blood, the pH of blood will not change greatly, thus maintaining a relatively stable state.
Principle: Acidic substances enter the blood, h++ HCO 3-= = = h2co 3.
H2CO3 = = = H2O+CO2 = (excreted from the lungs)
For example, after lactic acid enters the blood, it reacts with NaHCO3 in the blood to generate sodium lactate and H2CO3.
When alkaline substances enter the blood, OH-+H2CO3 = = = HCO3-+H2O.
For example, when Na2CO3 enters the blood. It reacts with H2CO3 in blood to generate bicarbonate, and excess bicarbonate can be excreted by the kidney.
3, the body temperature is constant
Both humans and higher animals have a certain body temperature, which is an important condition for metabolism (biochemical reaction) and normal life activities. The heat production of human body is the result of energy metabolism. When quiet, it mainly comes from internal organs (liver, kidney, etc. ), and it mainly comes from skeletal muscle during exercise, which is more than 10 times higher than that at rest. People often fight "chills" in cold environment, and the heat production increases obviously. The heat dissipation of the human body mainly passes through the skin. When the temperature reaches above 35℃, the heat dissipation of human body is mainly through sweat evaporation. The relatively constant body temperature is due to the dynamic balance between heat production and heat dissipation, and the main regulation center is in the hypothalamus.
4. Water balance, salt balance, blood sugar balance and body temperature balance
5. Feedback adjustment: positive feedback and negative feedback.
Feedback is the phenomenon that the result of a process returns to affect the process.
Positive feedback: positive feedback refers to the process of promoting results, that is, the products of the reaction in turn promote the reaction. Feedback information is not to limit the activities of the control part, but to promote and strengthen the activities of the control part. Similar to the relationship between elevated blood glucose concentration and elevated insulin concentration. The significance of positive feedback is to strengthen the physiological process until the physiological function is finally completed. In the case of positive feedback, the feedback control system is in a regenerative state. Common positive feedback in life activities includes defecation, urination, ejaculation, childbirth and coagulation.
Negative feedback: negative feedback refers to the process of result inhibition, that is, the products of the reaction in turn inhibit the progress of the reaction. The feedback information acts in the opposite direction to the control information, so the influence of the control information can be corrected. Similar to the relationship between the increase of blood glucose concentration and the decrease of glucagon concentration. The main significance of negative feedback regulation is to maintain the steady state of the internal environment of the body. In the case of negative feedback, the feedback control system is usually in a stable state. The regulation of water balance, salt balance, blood sugar balance and body temperature balance belongs to negative feedback regulation.
The significance of internal environment homeostasis
Steady state is a state in which the internal environment is relatively stable (dynamic balance), which means that the concentration of various substances and the physical and chemical factors of the internal environment are relatively constant, and it is realized under the adjustment of factors such as nerves, body fluids and immunity. Steady state is a relatively stable state of internal environment, not absolute stability.
The metabolism of the body is composed of many complex enzymatic reactions in cells, and the enzymatic reactions need mild external conditions, such as temperature and pH, to make the enzymatic reactions run normally. It can be seen that the steady state of the internal environment is a necessary condition for the body to carry out normal life activities.
When the homeostasis of the internal environment is destroyed, it will cause cell metabolism disorder and lead to diseases. For example, the decrease of calcium and phosphorus content in blood will affect the calcification of bone tissue, which is manifested as osteomalacia in adults and rickets in children with bone growth disorder and incomplete ossification. Too high blood calcium can cause muscle weakness, and too low blood calcium can cause muscle twitching and other diseases.
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Senior high school biology learning skills
(1) Simplified mnemonic method
That is, by analyzing the teaching materials, find out the main points and simplify the knowledge into regular words to help remember. For example, the molecular structure of DNA can be simplified as "5432 1", that is, five basic elements and four basic units, each unit has three basic substances, and many units form two deoxynucleotide chains, which become a regular double helix structure.
(2) Associative memory method
That is, according to the content of the textbook, skillfully use association to help memory. For example, remember trace elements: iron, manganese, boron, zinc, molybdenum and copper. You can use homophonic memory to remember that iron hit a new bucket, so that you can remember it and not forget it easily.
(3) Comparative memory method
In biology learning, there are many similar nouns that are easily confused and difficult to remember. For such content, you can remember it by comparison. Comparative method is to list related nouns separately, and then compare them from the aspects of scope, connotation, extension and even words, and find out the differences by retaining similarities. This contrast is obvious and easy to remember. For example, assimilation and alienation, aerobic respiration and anaerobic respiration, hormone regulation and nerve regulation, material circulation and energy flow.
(4) diffraction memory method
This method takes an important knowledge point as the core, and establishes as many connections as possible with other related knowledge through the divergent process of thinking. This method is mostly used to summarize or review chapter knowledge, and can also be used to link related knowledge scattered in various chapters. For example, the concept, development, theory, type, composition, structure, function and division of cells should be diffracted.
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How to learn high school biology well
First, master the learning rules of biology in senior high school
Law is the inevitable connection of the intrinsic essence of things themselves. Biology learning has its own rules, and mastering the learning rules of these creatures will help to understand and apply biological knowledge. Learning biology, like other subjects, should also follow the cognitive law. We need to understand that people's understanding is from shallow to deep, from less to more, gradually accumulating and deepening. Therefore, learning can't be done in a hurry, it needs constant efforts, and we will be able to accurately master biological knowledge and form learning ability. Learning biology also requires a strong interest in learning. With interest, students will find high school biology really interesting.
Second, break through the difficulties of biology learning in senior high school
Some biological knowledge is complicated, but because it is too abstract, students find it a bit difficult to learn. At this time, it is necessary to turn the difficult into the easy and strive to break through the difficulties. Because experiments can deepen students' understanding and memory of biological knowledge points. Therefore, students can do more biological experiments according to the contents in books.
There are many knowledge difficulties in biology learning in the complicated life movement process, which requires us to grasp the main contradictions and make our knowledge clear at a glance. The farther away from concrete things, the more abstract thinking. Some biological knowledge has little connection with reality, so it is difficult for students to understand. Therefore, learning biology often needs the help of graphics, specimens, videos and other visual means to help understand some abstract knowledge and improve the understanding effect of knowledge. When learning biology, it is a good way to break through the difficulties by organizing scattered knowledge, concretizing theoretical knowledge and specializing general problems.
Third, be good at summing up the knowledge of biology in senior high school.
In the process of learning the new biology curriculum, we can learn knowledge in blocks. After learning, the knowledge of each block is linked and summarized into systematic biological knowledge. This can not only form a complete knowledge structure in the brain, but also facilitate understanding and memory, and can be used comprehensively. All knowledge points should be connected in series according to their own logical relationship. It is necessary to master the internal relationship between knowledge points, clarify the vertical and horizontal relationship between points and lines, and expand from line to surface into a knowledge network. We should focus on the key points, mainstream and summary, rather than covering everything.
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