If you place human red blood cells in a solution of salts, the concentration of which. The state of red blood cells in NaCl solutions of various concentrations. What happens to red blood cells in a physiological solution
According to the program I.N. Ponomareva.
Textbook: Biology Human. A.G. Dragomilov, R.D. Mash.
Lesson type:
1. for the main didactic purpose - learning new material;
2. according to the method of conduct and stages of the educational process - combined.
Lesson methods:
1. by the nature of cognitive activity: explanatory-illustrated, problem-searching.
2. by type of knowledge source: verbal-visual.
3. according to the form of joint activity between teacher and students: story, conversation
Goal: To deepen the meaning of the internal environment of the body and homeostasis; explain the mechanism of blood clotting; continue to develop microscopy skills.
Didactic tasks:
1) Composition of the internal environment of the body
2) Blood composition and its functions
3) Blood clotting mechanism
1) Name the components of the internal environment of the human body
2) Determine blood cells under a microscope, drawings: red blood cells, leukocytes, platelets
3) Indicate the functions of blood cells
4) Characterize the constituent components of blood plasma
5) Establish the relationship between the structure and functions of blood cells
6) Explain the importance of blood tests as a means of diagnosing diseases. Justify your opinion.
Developmental tasks:
1) The ability to carry out tasks, guided by methodological instructions.
2) Extract the necessary information from knowledge sources.
3) The ability to draw conclusions after viewing slides on the topic “Blood”
4) Ability to fill out diagrams
5) Analyze and evaluate information
6) Develop creative abilities in students
Educational tasks:
1) Patriotism on the life activity of I.I. Mechnikov
2) Formation of a healthy lifestyle: a person must monitor the composition of his blood, eat foods rich in protein and iron, avoid blood loss and dehydration.
3) Create conditions for the formation of personal self-esteem.
Requirements for the level of training of students:
Learn:
- blood cells under a microscope, drawings
Describe:
- blood cell functions;
- blood clotting mechanism;
- function of the constituent components of blood plasma;
- signs of anemia, hemophilia
Compare:
- young and mature human erythrocyte;
- human and frog erythrocytes;
- the number of red blood cells in newborns and adults.
Blood plasma, erythrocytes, leukocytes, platelets, homeostasis, phagocytes, fibrinogens, blood coagulation, thromboplastin, neutrophils, eosinophils, basophils, monocytes, lymphocytes, isotonic, hypertonic, hypotonic solutions, saline.
Equipment:
1) Table “Blood”
2) Electronic disk “Cyril and Methodius”, theme “Blood”
3) Whole human blood (centrifuged and plain).
4) Microscopes
5) Microspecimens: human and frog blood.
6) Raw potatoes in distilled water and salt
7) Saline solution
8) 2 red robes, white robe, balloons
9) Portraits of I.I. Mechnikov and A. Levenguk
10) Plasticine red and white
11) Presentations by students.
Lesson steps
1. Updating basic knowledge.
Claude Bernard: “I was the first to insist on the idea that for animals there are actually 2 environments: one environment is external, in which the organism is located, and the other environment is internal, in which tissue elements live.
Fill the table.
“Components of the internal environment and their location in the body.” See Appendix No. 1.
2.Learning new material
Mephistopheles, inviting Faust to sign an alliance with “evil spirits,” said: “Blood, you need to know, is a very special juice.” These words reflect the mystical belief in blood as something mysterious.
Blood was recognized as a powerful and exceptional force: blood was sealed with sacred oaths; the priests made their wooden idols “cry blood”; The ancient Greeks sacrificed blood to their gods.
Some philosophers of Ancient Greece considered blood to be the carrier of the soul. The ancient Greek physician Hippocrates prescribed the blood of healthy people to the mentally ill. He thought that in the blood of healthy people there is a healthy soul.
Indeed, blood is the most amazing tissue of our body. Blood mobility is the most important condition for the life of the body. Just as it is impossible to imagine a state without transport communication lines, it is impossible to understand the existence of a person or animal without the movement of blood through the vessels, when oxygen, water, proteins and other substances are distributed to all organs and tissues. With the development of science, the human mind penetrates deeper and deeper into the many secrets of blood.
So, the total amount of blood in the human body is equal to 7% of its weight, in volume it is about 5-6 liters in an adult and about 3 liters in adolescents.
What functions does blood perform?
Student: Demonstrates basic notes and explains the functions of blood. See Appendix No. 2
At this time, the teacher makes additions to the “Blood” electronic disk.
Teacher: What does blood consist of? Shows centrifuged blood, where two clearly distinct layers are visible.
The top layer is a slightly yellowish translucent liquid - blood plasma and the bottom layer is a dark red sediment, which is formed by formed elements - blood cells: leukocytes, platelets and erythrocytes.
The peculiarity of blood lies in the fact that it is a connective tissue, the cells of which are suspended in a liquid intermediate substance - plasma. In addition, cell proliferation does not occur in it. The replacement of old, dying blood cells with new ones is carried out thanks to hematopoiesis that occurs in the red bone marrow, which fills the space between the bone crossbars with the spongy substance of all bones. For example, the destruction of aged and damaged red blood cells occurs in the liver and spleen. Its total volume in an adult is 1500 cm 3 .
Blood plasma contains many simple and complex substances. 90% of plasma is water, and only 10% of it is dry residue. But how diverse its composition is! Here are the most complex proteins (albumin, globulins and fibrinogen), fats and carbohydrates, metals and halogens - all elements of the periodic table, salts, alkalis and acids, various gases, vitamins, enzymes, hormones, etc.
Each of these substances has a certain important meaning.
Student with a crown “Squirrels” are the “building material” of our body. They participate in blood clotting processes, maintain a constant blood reaction (weakly alkaline), and form immunoglobulins and antibodies that participate in the body’s defense reactions. High molecular weight proteins that do not penetrate the walls of blood capillaries retain a certain amount of water in the plasma, which is important for a balanced distribution of fluid between the blood and tissues. The presence of proteins in plasma ensures the viscosity of the blood, the constancy of its vascular pressure, and prevents the sedimentation of red blood cells.
Student with a crown “fats and carbohydrates” are sources of energy. Salts, alkalis and acids maintain the constancy of the internal environment, changes in which are life-threatening. Enzymes, vitamins and hormones ensure proper metabolism in the body, its growth, development and mutual influence of organs and systems.
Teacher: The total concentration of mineral salts, proteins, glucose, urea and other substances dissolved in plasma creates osmotic pressure.
The phenomenon of osmosis occurs wherever there are 2 solutions of different concentrations, separated by a semi-permeable membrane through which the solvent (water) easily passes, but the molecules of the dissolved substance do not pass through. Under these conditions, the solvent moves towards a solution with a high concentration of solute.
Due to somatic pressure, fluid penetrates through cell membranes, which ensures the exchange of water between blood and tissues. The constancy of the osmotic pressure of the blood is important for the life of the body's cells. The membranes of many cells, including blood cells, are also semi-permeable. Therefore, when erythrocytes are placed in solutions with different salt concentrations, and, consequently, with different osmotic pressure, serious changes occur in them.
A saline solution that has the same osmotic pressure as blood plasma is called an isotonic solution. For humans, a 0.9% solution of table salt is isotonic.
A saline solution whose osmotic pressure is higher than the osmotic pressure of blood plasma is called hypertonic; if the osmotic pressure is lower than in blood plasma, then such a solution is called hypotonic.
Hypertonic solution (10% NaCl) - used in the treatment of purulent wounds. If a bandage with a hypertonic solution is applied to the wound, the liquid from the wound will come out onto the bandage, since the concentration of salts in it is higher than inside the wound. In this case, the liquid will carry along pus, microbes, and dead tissue particles, and as a result the wound will cleanse and heal.
Since the solvent always moves towards a solution with a higher osmotic pressure, when erythrocytes are immersed in a hypotonic solution, water, according to the law of osmosis, intensively begins to penetrate into the cells. Red blood cells swell, their membranes rupture, and the contents enter the solution.
For the normal functioning of the body, not only the quantitative content of salts in the blood plasma is important. The qualitative composition of these salts is also extremely important. The heart, for example, will stop if calcium salts are completely excluded from the fluid flowing through it, the same will happen if there is an excess of potassium salts. Solutions that correspond to the composition of plasma in their qualitative composition and salt concentration are called physiological solutions. They are different for different animals. Such fluids are used to maintain the vital functions of organs isolated from the body, and also as blood substitutes for blood loss.
Assignment: Prove that violation of the constancy of the salt composition of blood plasma by diluting it with distilled water leads to the death of red blood cells.
The experiment can be performed as a demonstration. The same amount of blood is poured into 2 test tubes. Distilled water is added to one sample, and physiological solution (0.9% NaCl solution) is added to the other. Students should notice that the test tube containing the saline solution remains opaque. Consequently, the formed elements of blood were preserved and remained in suspension. In a test tube where distilled water was added to the blood, the liquid became transparent. The contents of the test tube are no longer a suspension, but have become a solution. This means that the formed elements here, primarily red blood cells, were destroyed, and hemoglobin went into solution.
The experience can be recorded in the form of a table. See Appendix No. 3.
The importance of the constancy of the salt composition of blood plasma.
The reasons for the destruction of red blood cells due to water pressure in the blood can be explained as follows. Red blood cells have a semi-permeable membrane; it allows water molecules to pass through, but poorly allows salt ions and other substances to pass through. In erythrocytes and blood plasma, the percentage of water is approximately equal, therefore, in a certain unit of time, approximately the same number of water molecules enter the erythrocyte from the plasma as leave the erythrocyte into the plasma. When blood is diluted with water, the water molecules outside the red blood cells become larger than those inside. As a result, the number of water molecules penetrating the erythrocyte also increases. It swells, its membrane stretches, and the cell loses hemoglobin. It turns into plasma. The destruction of red blood cells in the human body can occur under the influence of various substances, for example, viper venom. Once in the plasma, hemoglobin is quickly lost: it easily passes through the walls of blood vessels, is excreted from the body by the kidneys, and is destroyed by liver tissue.
Violation of the composition of the plasma, like any other violation of the constancy of the composition of the internal environment, is possible only within relatively small limits. Thanks to nervous and humoral self-regulation, deviation from the norm causes changes in the body that restore the norm. Significant changes in the constancy of the composition of the internal environment lead to illness and sometimes even cause death.
A student in a red robe and a “red blood cell” crown with balloons in his hands:
Everything that is contained in the blood, everything that it carries through the vessels, is intended for the cells of our body. They take everything they need from it and use it for their own needs. Only the oxygen-containing substance should remain intact. After all, if it settles in the tissues, breaks down there and is used for the needs of the body, it will become difficult to transport oxygen.
At first, nature went to create very large molecules, the molecular weight of which was two or even ten million times that of hydrogen, the lightest substance. Such proteins are not able to pass through cell membranes, “getting stuck” even in fairly large pores; that is why they remained in the blood for a long time and could be used repeatedly. For higher animals, a more original solution was found. Nature provided them with hemoglobin, the molecular weight of which is only 16 thousand times greater than that of a hydrogen atom, but to prevent the hemoglobin from reaching the surrounding tissues, it placed it, as in containers, inside special cells that circulate with the blood - erythrocytes.
The red blood cells of most animals are round, although sometimes their shape for some reason changes and becomes oval. Among mammals, such freaks are camels and llamas. Why it was necessary to introduce such significant changes into the design of the red blood cells of these animals is still unknown.
At first, the red blood cells were large and bulky. In Proteus, a relict cave amphibian, their diameter is 35-58 microns. In most amphibians they are much smaller, but their volume reaches 1100 cubic microns. This turned out to be inconvenient. After all, the larger the cell, the relatively smaller its surface, in both directions of which oxygen must pass. There is too much hemoglobin per unit surface area, which prevents its full use. Convinced of this, nature took the path of reducing the size of red blood cells to 150 cubic microns for birds and to 70 for mammals. In humans, their diameter is 8 microns and their volume is 8 cubic microns.
The red blood cells of many mammals are even smaller; in goats they barely reach 4, and in musk deer 2.5 microns. Why goats have such small red blood cells is not difficult to understand. The ancestors of domestic goats were mountain animals and lived in a highly rarefied atmosphere. It is not for nothing that their number of red blood cells is huge, 14.5 million in every cubic millimeter of blood, while animals such as amphibians, whose metabolic rate is low, have only 40-170 thousand red blood cells.
In pursuit of volume reduction, the red blood cells of vertebrates turned into flat discs. In this way, the path of oxygen molecules diffusing into the depths of the erythrocyte was shortened as much as possible. In humans, in addition, there are depressions in the center of the disk on both sides, which made it possible to further reduce the volume of the cell, increasing the size of its surface.
Transporting hemoglobin in a special container inside an erythrocyte is very convenient, but there is no good without a silver lining. An erythrocyte is a living cell and itself consumes a lot of oxygen for its respiration. Nature does not tolerate waste. She had to rack her brain a lot to figure out how to cut unnecessary expenses.
The most important part of any cell is the nucleus. If it is quietly removed, and scientists know how to perform such ultramicroscopic operations, then the nuclear-free cell, although it does not die, still becomes unviable, stops its main functions, and sharply reduces metabolism. This is what nature decided to use; it deprived adult red blood cells of mammals of their nuclei. The main function of red blood cells was as containers for hemoglobin - a passive function, and it could not be harmed, and the reduction in metabolism was only beneficial, since this greatly reduced oxygen consumption.
Teacher: Make a red blood cell from red plasticine.
A student in a white coat and a “leukocyte” crown:
Blood is not only a vehicle. It also performs other important functions. Moving through the vessels of the body, the blood in the lungs and intestines almost directly comes into contact with the external environment. The lungs, and especially the intestines, are undoubtedly the dirty places of the body. It is not surprising that it is very easy for microbes to penetrate into the blood here. And why shouldn’t they penetrate? Blood is a wonderful nutrient medium, and rich in oxygen. If vigilant and implacable guards were not placed immediately at the entrance, the path of life of the organism would become the path of its death.
The guards were found without difficulty. Even at the dawn of life, all cells of the body were able to capture and digest particles of organic substances. Almost at the same time, organisms acquired motile cells very reminiscent of modern amoebas. They did not sit idly by, waiting for the flow of liquid to bring them something tasty, but spent their lives in constant search for their daily bread. These wandering hunter cells, which from the very beginning became involved in the fight against microbes that entered the body, were called leukocytes.
Leukocytes are the largest cells in human blood. Their size ranges from 8 to 20 microns. These orderlies of our body, dressed in white coats, took part in the digestive processes for a long time. They perform this function even in modern amphibians. It is not surprising that the lower animals have a lot of them. In fish, there are up to 80 thousand of them in 1 cubic millimeter of blood, ten times more than in a healthy person.
To successfully fight pathogenic microbes, you need a lot of leukocytes. The body produces them in huge quantities. Scientists have not yet been able to figure out their life expectancy. Yes, it is unlikely that it can be accurately established. After all, leukocytes are soldiers and, apparently, never live to old age, but die in war, in battles for our health. This is probably why different animals and different experimental conditions yielded very varied figures - from 23 minutes to 15 days. More accurately, it was only possible to establish the lifespan of lymphocytes, one of the varieties of tiny orderlies. It is equal to 10-12 hours, that is, per day the body completely renews the composition of lymphocytes at least twice.
Leukocytes are capable of not only wandering inside the bloodstream, but if necessary, they easily leave it, going deeper into the tissues, towards the microorganisms that have entered there. Devouring microbes dangerous to the body, leukocytes are poisoned by their potent toxins and die, but do not give up. Wave after wave of a solid wall they attack the pathogenic focus until the enemy’s resistance is broken. Each leukocyte can ingest up to 20 microorganisms.
Leukocytes crawl out in masses onto the surface of the mucous membranes, where there are always a lot of microorganisms. Only in the human oral cavity - 250 thousand every minute. Within a day, 1/80 of all our leukocytes die here.
Leukocytes fight not only germs. They are entrusted with another important function: to destroy all damaged, worn-out cells. In the tissues of the body, they constantly carry out dismantling, clearing places for the construction of new body cells, and young leukocytes also take part in the construction itself, at least in the construction of bones, connective tissue and muscles.
Of course, leukocytes alone would not be able to defend the body from microbes penetrating into it. There are many different substances in the blood of any animal that can glue, kill and dissolve microbes that have entered the circulatory system, convert them into insoluble substances and neutralize the toxin they secrete. We inherit some of these protective substances from our parents, while others we learn to produce ourselves in the fight against the countless enemies around us.
Teacher: Assignment: make a leukocyte from white plasticine.
A student in a pink robe and a “platelet” crown:
No matter how closely the control devices - baroreceptors - monitor the state of blood pressure, an accident is always possible. Even more often, trouble comes from outside. Any, even the most insignificant, wound will destroy hundreds, thousands of vessels, and through these holes the waters of the internal ocean will immediately pour out.
By creating an individual ocean for each animal, nature had to worry about organizing an emergency rescue service in case of destruction of its shores. At first this service was not very reliable. Therefore, for lower creatures, nature has provided for the possibility of significant shallowing of inland reservoirs. A loss of 30 percent of blood is fatal for humans; the Japanese beetle easily tolerates a loss of 50 percent of hemolymph.
If a ship gets a hole at sea, the crew tries to plug the resulting hole with any auxiliary material. Nature has abundantly supplied the blood with its own patches. These are special spindle-shaped cells - platelets. They are negligible in size, only 2-4 microns. It would be impossible to plug any significant hole with such a tiny plug if platelets did not have the ability to stick together under the influence of thrombokinase. Nature has richly supplied this enzyme to the tissues surrounding the vessels and other places most susceptible to injury. At the slightest damage to tissue, thrombokinase is released out, comes into contact with the blood, and platelets immediately begin to stick together, forming a lump, and the blood brings it more and more building material, because every cubic millimeter of blood contains 150-400 thousand of them.
Platelets by themselves cannot form a large plug. The plug is obtained by the loss of threads of a special protein - fibrin, which in the form of fibrinogen is constantly present in the blood. In the formed network of fibrin fibers, lumps of sticky platelets, erythrocytes, and leukocytes freeze. A few minutes pass and a significant traffic jam forms. If the damaged vessel is not very large and the blood pressure in it is not high enough to push the plug out, the leak will be eliminated.
It is hardly cost-effective for the emergency service on duty to consume a lot of energy, and therefore oxygen. The only task platelets have is to stick together in a moment of danger. The function is passive, does not require significant energy expenditure, which means there is no need to consume oxygen while everything in the body is calm, and nature is with them the same way as with red blood cells. She deprived them of their nuclei and thereby, reducing the level of metabolism, greatly reduced oxygen consumption.
It is obvious that a well-established emergency blood service is necessary, but, unfortunately, it poses a terrible danger to the body. What if, for one reason or another, the emergency service starts working at the wrong time? Such inappropriate actions will result in a serious accident. The blood in the vessels will clot and clog them. Therefore, the blood has a second emergency service - the anti-clotting system. She makes sure that there is no thrombin in the blood, the interaction of which with fibrinogen leads to the loss of fibrin threads. As soon as fibrin appears, the anticoagulation system immediately inactivates it.
The second emergency service is very active. If a significant dose of thrombin is introduced into the blood of a frog, nothing terrible will happen; it will be immediately neutralized. But if you now take blood from this frog, it turns out that it has lost the ability to clot.
The first emergency system works automatically, the second is commanded by the brain. Without his instructions, the system will not work. If you first destroy the command post in the frog, located in the medulla oblongata, and then inject thrombin, the blood will instantly clot. Emergency services are ready, but there is no one to sound the alarm.
In addition to the emergency services listed above, the blood also has a major repair team. When the circulatory system is damaged, not only is the rapid formation of a blood clot important, its timely removal is also necessary. While the torn vessel is plugged with a plug, it interferes with the healing of the wound. The repair team, restoring the integrity of the tissues, little by little dissolves and resolves the blood clot.
Numerous watchdog, control and emergency services reliably protect the waters of our internal ocean from any surprises, ensuring very high reliability of the movement of its waves and the invariability of their composition.
Teacher: Explanation of the mechanism of blood clotting.
Blood clotting
Thromboplastin + Ca 2+ + prothrombin = thrombin
Thrombin + fibrinogen = fibrin
Thromboplastin is an enzyme protein formed during the destruction of platelets.
Ca 2+ are calcium ions present in blood plasma.
Prothrombin is an inactive protein enzyme in blood plasma.
Thrombin is an active enzyme protein.
Fibrinogen is a protein dissolved in blood plasma.
Fibrin – protein fibers insoluble in blood plasma (thrombus)
Throughout the lesson, students fill out the “Blood Cells” table and then compare it with the standard table. They check with each other and give a grade based on the criteria proposed by the teacher. See Appendix No. 4.
Practical part of the lesson.
Teacher: Task No. 1
Examine blood under a microscope. Describe red blood cells. Determine whether this blood can belong to a person.
Students are offered frog blood for analysis.
During the conversation, students answer the questions:
1.What color are the red blood cells?
Answer: The cytoplasm is pink, the nucleus is colored blue with nuclear dyes. Staining makes it possible not only to better distinguish cellular structures, but also to find out their chemical properties.
2. What size are red blood cells?
Answer: Quite large, however, there are not many of them in sight.
3. Could this blood belong to a person?
Answer: It can't. Humans are mammals, and mammalian red blood cells do not have a nucleus.
Teacher: Task No. 2
Compare human and frog red blood cells.
When comparing, note the following. Human red blood cells are much smaller than frog red blood cells. In the field of view of a microscope, there are significantly more human red blood cells than frog red blood cells. The absence of a nucleus increases the useful capacity of the red blood cell. From these comparisons it is concluded that human blood is capable of binding more oxygen than frog blood.
Enter the information into the table. See Appendix No. 5.
3. Consolidation of the studied material:
1. Using the medical form “Blood Test”, see Appendix No. 6, describe the composition of the blood:
a) Amount of hemoglobin
b) Number of red blood cells
c) Leukocyte count
d) ROE and ESR
d) Leukocyte formula
f) Diagnose a person’s health condition
2. Work according to options:
1.Option: test work on 5 questions with a choice of one to several questions.
2.Option: select sentences that contain errors and correct these errors.
Option 1
1.Where are red blood cells produced?
a) liver
b) red bone marrow
c) spleen
2.Where are red blood cells destroyed?
a) liver
b) red bone marrow
c) spleen
3.Where are leukocytes formed?
a) liver
b) red bone marrow
c) spleen
d) lymph nodes
4.What blood cells have a nucleus?
a) red blood cells
b) leukocytes
c) platelets
5. What formed elements of blood are involved in its coagulation?
a) red blood cells
b) platelets
c) leukocytes
Option 2
Find sentences with errors and correct them:
1. The internal environment of the body is blood, lymph, tissue fluid.
2. Erythrocytes are red blood cells that have a nucleus.
3. Leukocytes participate in the body’s defense reactions and have an amoeboid shape and a nucleus.
4. Platelets have a nucleus.
5. Red blood cells are destroyed in the red bone marrow.
Tasks for logical thinking:
1. The concentration of salts of physiological solution, which sometimes replaces blood in experiments, is different for cold-blooded animals (0.65%) and warm-blooded animals (0.95%). How can you explain this difference?
2. If you add clean water to the blood, the blood cells burst; If you place them in a concentrated salt solution, they shrink. Why doesn't this happen if a person drinks a lot of water and eats a lot of salt?
3. When keeping tissues alive in the body, they are placed not in water, but in a physiological solution containing 0.9% table salt. Explain why it is necessary to do this?
4. Human red blood cells are 3 times smaller than frog red blood cells, but there are 13 times more of them per 1 mm3 in humans than in frogs. How can you explain this fact?
5. Pathogenic microbes that enter any organ can penetrate the lymph. If microbes got from it into the blood, this would lead to a general infection of the body. However, this does not happen. Why?
6. In 1 mm 3 of goat blood there are 10 million red blood cells measuring 0.007; in the blood of a frog 1 mm 3 – 400,000 red blood cells measuring 0.02. Whose blood - human, frog or goat - will carry more oxygen per unit time? Why?
7. When climbing a mountain quickly, healthy tourists develop “mountain sickness” - shortness of breath, palpitations, dizziness, weakness. These signs disappear over time with frequent training. Can you imagine what changes occur in human blood?
4. Homework
clauses 13,14. Know the notes in the notebook, work No. 50,51 p. 35 – workbook No. 1, authors: R.D. Mash and A.G. Dragomilov
Creative task for students:
"Immune memory"
“The work of E. Jenner and L. Pasteur in the study of immunity.”
“Human viral diseases.”
Reflection: Guys, raise your hands for those who felt comfortable and cozy in class today.
- Do you think we achieved the goal of the lesson?
- What did you like most about the lesson?
- What would you like to change during the lesson?
Classes
Exercise 1. The task includes 60 questions, each of them has 4 possible answers. For each question, select only one answer that you consider the most complete and correct. Place a “+” sign next to the index of the selected answer. In case of correction, the “+” sign must be duplicated.
- Muscle tissue is formed:
a) only mononuclear cells;
b) only multinuclear muscle fibers;
c) binuclear fibers tightly adjacent to each other;
d) mononuclear cells or multinucleated muscle fibers. + - Muscle tissue is formed by striated cells that make up the fibers and interact with each other at the points of contact:
a) smooth;
b) cardiac; +
c) skeletal;
d) smooth and skeletal. - Tendons, through which muscles are connected to bones, are formed by connective tissue:
a) bone;
b) cartilaginous;
c) loose fibrous;
d) dense fibrous. + - The anterior horns of the gray matter of the spinal cord (“butterfly wings”) are formed by:
a) interneurons;
b) bodies of sensory neurons;
c) axons of sensory neurons;
d) bodies of motor neurons. + - The anterior roots of the spinal cord are formed by the axons of neurons:
a) motor; +
b) sensitive;
c) only intercalary ones;
d) intercalary and sensitive. - The centers of protective reflexes - coughing, sneezing, vomiting are located in:
a) cerebellum;
c) spinal cord;
c) intermediate part of the brain;
d) medulla oblongata of the brain. + - Red blood cells placed in a physiological solution of table salt:
a) wrinkle;
b) swell and burst;
c) stick to each other;
d) remain without external changes. + - Blood flows faster in vessels whose total lumen is:
a) the largest;
b) the smallest; +
c) average;
d) slightly above average. - The significance of the pleural cavity is that it:
a) protects the lungs from mechanical damage;
b) prevents overheating of the lungs;
c) participates in the removal of a number of metabolic products from the lungs;
d) reduces friction of the lungs against the walls of the chest cavity, participates in the mechanism of stretching of the lungs. + - The significance of bile produced by the liver and entering the duodenum is that it:
a) breaks down difficult-to-digest proteins;
b) breaks down hard-to-digest carbohydrates;
c) breaks down proteins, carbohydrates and fats;
d) increases the activity of enzymes secreted by the pancreas and intestinal glands, facilitating the breakdown of fats. + - Photosensitivity of rods:
a) not developed;
b) the same as for cones;
c) higher than that of cones; +
d) lower than that of cones. - Jellyfish reproduce:
a) only through sexual intercourse;
b) only asexually;
c) sexually and asexually;
d) some species are only sexual, others are sexual and asexual. + - Why do children develop new signs that are not characteristic of their parents:
a) since all the gametes of the parents are of different types;
b) since during fertilization the gametes fuse randomly;
c) in children, parental genes are combined in new combinations; +
d) since the child receives one half of the genes from the father, and the other from the mother. - The flowering of some plants only in daylight conditions is an example:
a) apical dominance;
b) positive phototropism; +
c) negative phototropism;
d) photoperiodism. - Filtration of blood in the kidneys occurs in:
a) pyramids;
b) pelvis;
c) capsules; +
d) medulla. - When secondary urine is formed, the following are returned to the bloodstream:
a) water and glucose; +
b) water and salts;
c) water and proteins;
d) all of the above products. - For the first time among vertebrates, amphibians have glands:
a) salivary; +
b) sweat;
c) ovaries;
d) greasy. - The lactose molecule consists of residues:
a) glucose;
b) galactose;
c) fructose and galactose;
d) galactose and glucose.
- The following statement is incorrect:
a) felines - a family of the carnivorous order;
b) hedgehogs - a family of insectivores;
c) hare - a genus of rodent order; +
d) tiger - a species of the panther genus.
45. Protein synthesis does NOT require:
a) ribosomes;
b) t-RNA;
c) endoplasmic reticulum; +
d) amino acids.
46. The following statement is true for enzymes:
a) enzymes lose some or all of their normal activity if their tertiary structure is destroyed; +
b) enzymes provide the energy necessary to stimulate the reaction;
c) enzyme activity does not depend on temperature and pH;
d) enzymes act only once and then are destroyed.
47. The greatest release of energy occurs in the process:
a) photolysis;
b) glycolysis;
c) Krebs cycle; +
d) fermentation.
48. The most characteristic features of the Golgi complex, as a cell organelle:
a) increasing the concentration and compaction of intracellular secretion products intended for release from the cell; +
b) participation in cellular respiration;
c) carrying out photosynthesis;
d) participation in protein synthesis.
49. Cellular organelles that transform energy:
a) chromoplasts and leucoplasts;
b) mitochondria and leukoplasts;
c) mitochondria and chloroplasts; +
d) mitochondria and chromoplasts.
50. The number of chromosomes in tomato cells is 24. Meiosis occurs in a tomato cell. Three of the resulting cells degenerate. The last cell immediately divides by mitosis three times. As a result, in the resulting cells you can find:
a) 4 nuclei with 12 chromosomes each;
b) 4 nuclei with 24 chromosomes each;
c) 8 nuclei with 12 chromosomes each; +
d) 8 nuclei with 24 chromosomes each.
51. Eyes in arthropods:
a) everyone has complex ones;
b) complex only in insects;
c) complex only in crustaceans and insects; +
d) complex in many crustaceans and arachnids.
52. The male gametophyte in the pine reproduction cycle is formed after:
a) 2 divisions;
b) 4 divisions; +
c) 8 divisions;
d) 16 divisions.
53. The final linden bud on the shoot is:
a) apical;
b) lateral; +
c) can be a subordinate clause;
d) sleeping.
54. The signal sequence of amino acids required for the transport of proteins into chloroplasts is located:
a) at the N-terminus; +
b) at the C-terminus;
c) in the middle of the chain;
d) different for different proteins.
55. Centrioles double into:
a) G 1 phase;
b) S-phase; +
c) G 2 phase;
d) mitosis.
56. Of the following connections, the least rich in energy:
a) the bond of the first phosphate with ribose in ATP; +
b) the connection of an amino acid with tRNA in aminoacyl-tRNA;
c) the connection of phosphate with creatine in creatine phosphate;
d) the bond of acetyl to CoA in acetyl-CoA.
57. The phenomenon of heterosis is usually observed when:
a) inbreeding;
b) distant hybridization; +
c) creating genetically pure lines;
d) self-pollination.
Task 2. The task includes 25 questions, with several answer options (from 0 to 5). Place "+" signs next to the indices of the selected answers. In case of corrections, the “+” sign must be duplicated.
- Furrows and convolutions are characteristic of:
a) diencephalon;
b) medulla oblongata;
c) cerebral hemispheres; +
d) cerebellum; +
e) midbrain. - In the human body, proteins can be directly converted into:
a) nucleic acids;
b) starch;
c) fats; +
d) carbohydrates; +
e) carbon dioxide and water. - The middle ear contains:
a) hammer; +
b) auditory (Eustachian) tube; +
c) semicircular canals;
d) external auditory canal;
d) stirrup. + - Conditioned reflexes are:
a) species;
b) individual; +
c) permanent;
d) both permanent and temporary; +
d) hereditary.
5. The centers of origin of certain cultivated plants correspond to specific land regions of the Earth. This is because these places:
a) were most optimal for their growth and development;
b) they were subject to serious natural disasters, which contributed to their preservation;
c) geochemical anomalies with the presence of certain mutagenic factors;
d) were free from specific pests and diseases;
e) were the centers of ancient civilizations, where the primary selection and reproduction of the most productive varieties of plants took place. +
6. One population of animals is characterized by:
a) free crossing of individuals; +
b) the possibility of meeting individuals of different sexes; +
c) similarity in genotype;
d) similar living conditions; +
e) balanced polymorphism. +
7. The evolution of organisms leads to:
a) natural selection;
b) diversity of species; +
c) adaptation to living conditions; +
d) mandatory promotion of the organization;
d) the occurrence of mutations.
8. The cell surface complex includes:
a) plasmalemma; +
b) glycocalyx; +
c) cortical layer of cytoplasm; +
d) matrix;
e) cytosol.
9. Lipids that make up the cell membranes of Escherichia coli:
a) cholesterol;
b) phosphatidylethanolamine; +
c) cardiolipin; +
d) phosphatidylcholine;
e) sphingomyelin.
- Adventitious buds can form during cell division:
a) pericycle; +
b) cambium; +
c) sclerenchyma;
d) parenchyma; +
e) wound meristem. + - Adventitious roots can form during cell division:
a) traffic jams;
b) crusts;
c) phellogen; +
d) phelloderms; +
e) medullary rays. + - Substances synthesized from cholesterol:
a) bile acids; +
b) hyaluronic acid;
c) hydrocortisone; +
d) cholecystokinin;
d) estrone. + - Deoxynucleotide triphosphates are necessary for the process:
a) replication; +
b) transcriptions;
c) broadcasts;
d) dark reparation; +
e) photoreactivation. - The process that results in the transfer of genetic material from one cell to another:
a) transition;
b) transversion;
c) translocation;
d) transduction; +
d) transformation. + - Organelles that absorb oxygen:
a) core;
b) mitochondria; +
c) peroxisomes; +
d) Golgi apparatus;
e) endoplasmic reticulum. + - The inorganic basis of the skeleton of various living organisms can be composed of:
a) CaCO 3; +
b) SrSO 4; +
c) SiO 2; +
d) NaCl;
e) Al 2 O 3. - They are of polysaccharide nature:
a) glucose;
b) cellulose; +
c) hemicellulose; +
d) pectin; +
e) lignin. - Proteins containing heme:
a) myoglobin; +
b) FeS – mitochondrial proteins;
c) cytochromes; +
d) DNA polymerase;
e) myeloperoxidase. + - Which of the factors of evolution were first proposed by Charles Darwin:
a) natural selection; +
b) genetic drift;
c) population waves;
d) isolation;
d) struggle for existence. + - Which of the following characteristics that arose during evolution are examples of idioadaptations:
a) warm-blooded;
b) hair of mammals; +
c) exoskeleton of invertebrates; +
d) external gills of the tadpole;
e) horny beak in birds. + - Which of the following selection methods appeared in the twentieth century:
a) interspecific hybridization;
b) artificial selection;
c) polyploidy; +
d) artificial mutagenesis; +
e) cell hybridization. +
22. Anemophilous plants include:
a) rye, oats; +
b) hazel, dandelion;
c) aspen, linden;
d) nettle, hemp; +
d) birch, alder. +
23. All cartilaginous fish have:
a) conus arteriosus; +
b) swim bladder;
c) spiral valve in the intestine; +
d) five gill slits;
e) internal fertilization. +
24. Representatives of marsupials live:
a) in Australia; +
b) in Africa;
c) in Asia;
d) in North America; +
d) in South America. +
25. The following features are characteristic of amphibians:
a) have only pulmonary breathing;
b) have a bladder;
c) larvae live in water, and adults live on land; +
d) adult individuals are characterized by molting;
d) there is no chest. +
Task 3. A task to determine the correctness of judgments (Place a “+” sign next to the numbers of correct judgments). (25 judgments)
1. Epithelial tissues are divided into two groups: integumentary and glandular. +
2. In the pancreas, some cells produce digestive enzymes, while others produce hormones that affect carbohydrate metabolism in the body.
3. Physiological, called a solution of table salt of 9% concentration. +
4. During prolonged fasting, when the level of glucose in the blood decreases, the glycogen disaccharide present in the liver is broken down.
5. Ammonia, formed during the oxidation of proteins, is converted in the liver into a less toxic substance, urea. +
6. All ferns need water for fertilization. +
7. Under the influence of bacteria, milk turns into kefir. +
8. During the dormant period, the vital processes of the seeds stop.
9. Bryophytes are a dead-end branch of evolution. +
10. Polysaccharides predominate in the main substance of the plant cytoplasm. +
11. Living organisms contain almost all the elements of the periodic table. +
12. Pea tendrils and cucumber tendrils are similar organs. +
13. The disappearance of the tail in frog tadpoles occurs due to the fact that dying cells are digested by lysosomes. +
14. Each natural population is always homogeneous in terms of the genotypes of individuals.
15. All biocenoses necessarily include autotrophic plants.
16. The first higher terrestrial plants were rhyniophytes. +
17. All flagellates are characterized by the presence of a green pigment - chlorophyll.
18. In protozoa, each cell is an independent organism. +
19. The ciliate slipper belongs to the phylum Protozoa.
20. Scallops move in a reactive manner. +
21. Chromosomes are the leading components of the cell in the regulation of all metabolic processes. +
22. Algae spores can be formed by mitosis. +
23. In all higher plants, the sexual process is oogamous. +
24. Fern spores divide meiotically to form a prothallus, the cells of which have a haploid set of chromosomes.
25. Ribosomes are formed by self-assembly. +
27. 10 – 11 grade
28. Task 1:
29. 1–d, 2–b, 3–d, 4–d, 5–a, 6–d, 7–d, 8–b, 9–d, 10–d, 11–c, 12–d, 13–c, 14–b, 15–c, 16–a, 17–a, 18–d, 19–c, 20–d, 21–a, 22–d, 23–d, 24–b, 25– d, 26–g, 27–b, 28–c, 29–g, 30–g, 31–c, 32–a, 33–b, 34–b, 35–b, 36–a, 37–c, 38–b, 39–c, 40–b, 41–b, 42–d, 43–c, 44–b, 45–c, 46–a, 47–c, 48–a, 49–c, 50– c, 51–c, 52–b, 53–b, 54–a, 55–b, 56–a, 57–b, 58–c, 59–b, 60–b.
30. Task 2:
31. 1 – c, d; 2 – c, d; 3 – a, b, d; 4 – b, d; 5 – d; 6 – a, b, d, e; 7 – b, c; 8 – a, b, c; 9 – b, c; 10 – a, b, d, e; 11 – c, d, e; 12 – a, c, d; 13 – a, d; 14 – d, d; 15 – b, c, d; 16 – a, b, c; 17 – b, c, d; 18 – a, c, d; 19 – a, d; 20 – b, c, d; 21 – c, d, e; 22 – a, d, d; 23 – a, c, d; 24 – a, d, d; 25 – v, d.
32. Task 3:
33. Correct judgments – 1, 3, 5, 6, 7, 9, 10, 11, 12, 13, 16, 18, 20, 21, 22, 23, 25.
constructor Create(ax, aY, aR, aColor, aShape_Type)
method Change_color (aColor)
method Resize(aR)
method Change_location (ax, aY)
method Change_shape_type (aShape_type)
End of description.
Parameter aShape_type will receive a value that specifies the drawing method to be attached to the object.
When using delegation, you must ensure that the method header matches the type of pointer used to store the method address.
Container classes.Containers - These are specially organized objects used to store and manage objects of other classes. To implement containers, special container classes are developed. A container class usually includes a set of methods that allow you to perform some operations on either an individual object or a group of objects.
As a rule, complex data structures (various types of lists, dynamic arrays, etc.) are implemented in the form of containers. The developer inherits from the element class a class to which he adds the information fields he needs, and receives the required structure. If necessary, it can inherit the class from the container class, adding its own methods to it (Fig. 1.30).
Rice. 1.30. Building classes based on
container class and element class
A container class typically includes methods for creating, adding, and removing elements. In addition, it must provide element-by-element processing (e.g., searching, sorting). All methods are programmed for element class objects. Methods for adding and removing elements when performing operations often refer to special fields of the element class used to create the structure (for example, for a singly linked list, a field storing the address of the next element).
Methods that implement element-by-element processing must work with data fields defined in descendant classes of the element class.
Element-by-element processing of the implemented structure can be carried out in two ways. The first method - universal - is to use iterators, the second is in the definition of a special method, which contains the address of the processing procedure in the list of parameters.
Theoretically, the iterator should provide the ability to implement cyclic actions of the following type:
<очередной элемент>:=<первый элемент>
cycle-bye<очередной элемент>defined
<выполнить обработку>
<очередной элемент>:=<следующий элемент>
Therefore, it usually consists of three parts: a method that allows you to organize data processing from the first element (obtaining the address of the first element of the structure); a method that organizes the transition to the next element, and a method that allows you to check the end of the data. Access to the next portion of data is carried out through a special pointer to the current portion of data (pointer to an element class object).
Example 1.12 Container class with iterator (List class). Let's develop a container class List that implements a linear singly linked list of objects of the Element class, described as follows:
Class Element:
field Pointer_to_next
End of description.
The List class must include three methods that make up the iterator: method Define_first, which should return a pointer to the first element, method Define_next, which should return a pointer to the next element, and a method End_of_list, which should return "yes" if the list is exhausted.
Class List
implementation
fields Pointer_to_first, Pointer_to_current
interface
method Add_before_first(aElement)
method Delete_last
method Define_first
method Define_next
method End_of_list
End of description.
Then element-by-element processing of the list will be programmed as follows:
Element:= Define_first
cycle-bye not End_of_list
Process an element, possibly overriding its type
Item: = Define _next
When using the second method of element-by-element processing of the implemented structure, the procedure for processing the element is passed in the list of parameters. Such a procedure can be determined if the type of processing is known, for example, the procedure for displaying the values of the object's information fields. The procedure must be called from a method for each data element. In strongly typed languages, the type of a procedure must be specified in advance, and it is often impossible to predict what additional parameters should be passed to the procedure. In such cases, the first method may be preferable.
Example 1.13 Container class with a procedure for processing all objects (List class). In this case, the List class will be described as follows:
Class List
implementation
fields Pointer_to_first, Pointer_to_current
interface
method Add_before_first(aElement)
method Delete_last
method Execute_for_all (aProcessing_procedure)
End of description.
Accordingly, the type of processing procedure must be described in advance, taking into account the fact that it must receive the address of the element being processed through parameters, for example:
Process_procedure (aElement)
Using polymorphic objects when creating containers allows you to create fairly universal classes.
Parameterized classes.Parameterized class(or sample) is a class definition in which some of the used types of class components are defined through parameters. So everyone template defines a group of classes, which, despite the difference in types, are characterized by the same behavior. It is impossible to redefine a type during program execution: all type specification operations are performed by the compiler (more precisely, by the preprocessor).
100 ml of blood plasma from a healthy person contains about 93 g of water. The rest of the plasma consists of organic and inorganic substances. Plasma contains minerals, proteins (including enzymes), carbohydrates, fats, metabolic products, hormones, and vitamins.
Plasma minerals are represented by salts: chlorides, phosphates, carbonates and sulfates of sodium, potassium, calcium, magnesium. They can be in the form of ions or in a non-ionized state.
Osmotic pressure of blood plasma
Even minor disturbances in the salt composition of plasma can be detrimental to many tissues, and above all to the cells of the blood itself. The total concentration of mineral salts, proteins, glucose, urea and other substances dissolved in plasma creates osmotic pressure.
The phenomena of osmosis occur wherever there are two solutions of different concentrations, separated by a semi-permeable membrane through which the solvent (water) easily passes, but the molecules of the dissolved substance do not pass through. Under these conditions, the solvent moves towards the solution with a higher solute concentration. One-way diffusion of liquid through a semi-permeable partition is called osmosis (Fig. 4). The force that causes solvent to move across a semipermeable membrane is osmotic pressure. Using special methods, it was possible to establish that the osmotic pressure of human blood plasma is maintained at a constant level and amounts to 7.6 atm (1 atm ≈ 105 N/m2).
Rice. 4. Osmotic pressure: 1 - pure solvent; 2 - saline solution; 3 - semi-permeable membrane dividing the vessel into two parts; the length of the arrows shows the speed of water movement through the membrane; A - osmosis, which began after filling both parts of the vessel with liquid; B - establishing balance; H-pressure balancing osmosis
The osmotic pressure of plasma is mainly created by inorganic salts, since the concentration of sugar, proteins, urea and other organic substances dissolved in plasma is low.
Thanks to osmotic pressure, fluid penetrates through cell membranes, which ensures the exchange of water between blood and tissues.
The constancy of the osmotic pressure of the blood is important for the life of the body's cells. The membranes of many cells, including blood cells, are also semi-permeable. Therefore, when blood cells are placed in solutions with different salt concentrations, and therefore with different osmotic pressure, serious changes occur in the blood cells due to osmotic forces.
A saline solution that has the same osmotic pressure as blood plasma is called an isotonic solution. For humans, a 0.9 percent solution of table salt (NaCl) is isotonic, and for a frog, a 0.6 percent solution of the same salt is isotonic.
A saline solution whose osmotic pressure is higher than the osmotic pressure of blood plasma is called hypertonic; if the osmotic pressure of a solution is lower than that in blood plasma, then such a solution is called hypotonic.
A hypertonic solution (usually a 10% sodium chloride solution) is used in the treatment of purulent wounds. If a bandage with a hypertonic solution is applied to the wound, the liquid from the wound will come out onto the bandage, since the concentration of salts in it is higher than inside the wound. In this case, the liquid will carry along pus, microbes, and dead tissue particles, and as a result, the wound will quickly cleanse and heal.
Since the solvent always moves towards a solution with a higher osmotic pressure, when erythrocytes are immersed in a hypotonic solution, water, according to the laws of osmosis, intensively begins to penetrate into the cells. Red blood cells swell, their membranes rupture, and the contents enter the solution. Hemolysis is observed. Blood, the red blood cells of which have undergone hemolysis, becomes transparent, or, as they sometimes say, lacquered.
In human blood, hemolysis begins when red blood cells are placed in a 0.44-0.48 percent NaCl solution, and in 0.28-0.32 percent NaCl solutions almost all red blood cells are destroyed. If red blood cells enter a hypertonic solution, they shrink. Make sure of this by doing experiments 4 and 5.
Note. Before carrying out laboratory work on blood testing, it is necessary to master the technique of taking blood from a finger for analysis.
First, both the subject and the researcher wash their hands thoroughly with soap. Then the subject’s ring (IV) finger of the left hand is wiped with alcohol. The skin of the flesh of this finger is pierced with a sharp and pre-sterilized special needle-feather. When you press on your finger, blood appears near the injection site.
The first drop of blood is removed with dry cotton wool, and the next one is used for research. It is necessary to ensure that the drop does not spread on the skin of the finger. Blood is drawn into a glass capillary by immersing its end into the base of the drop and giving the capillary a horizontal position.
After taking blood, the finger is wiped again with a cotton swab moistened with alcohol and then lubricated with iodine.
Experience 4
Place a drop of isotonic (0.9 percent) NaCl solution on one edge of the slide, and a drop of hypotonic (0.3 percent) NaCl solution on the other. Pierce the skin of your finger with a needle in the usual way and use a glass rod to transfer a drop of blood to each drop of solution. Mix the liquids, cover with coverslips and examine under a microscope (preferably at high magnification). Swelling of most red blood cells in a hypotonic solution is visible. Some of the red blood cells are destroyed. (Compare with red blood cells in isotonic solution.)
Experience 5
Take another slide. Place a drop of 0.9% NaCl solution on one edge, and a drop of hypertonic (10%) NaCl solution on the other. Add a drop of blood to each drop of solutions and, after mixing, examine them under a microscope. In a hypertonic solution, the size of red blood cells decreases and shrinks, which is easily detected by their characteristic scalloped edge. In an isotonic solution, the edge of red blood cells is smooth.
Despite the fact that different amounts of water and mineral salts may enter the blood, the osmotic pressure of the blood is maintained at a constant level. This is achieved thanks to the activity of the kidneys and sweat glands, through which water, salts and other metabolic products are removed from the body.
Saline
For the normal functioning of the body, it is important not only the quantitative content of salts in the blood plasma, which provides a certain osmotic pressure. The qualitative composition of these salts is also extremely important. An isotonic solution of sodium chloride is not capable of maintaining the functioning of the organ it washes for a long time. The heart, for example, will stop if calcium salts are completely excluded from the fluid flowing through it, the same will happen if there is an excess of potassium salts.
Solutions that correspond to the composition of plasma in their qualitative composition and salt concentration are called physiological solutions. They are different for different animals. In physiology, Ringer's and Tyrode's fluids are often used (Table 1).
Table 1. Composition of Ringer's and Tyrode's liquids (in g per 100 ml of water)
In liquids for warm-blooded animals, in addition to salts, glucose is often added and the solution is saturated with oxygen. Such fluids are used to maintain the vital functions of organs isolated from the body, and also as blood substitutes for blood loss.
Blood reaction
Blood plasma not only has a constant osmotic pressure and a certain qualitative composition of salts, it maintains a constant reaction. In practice, the reaction of the medium is determined by the concentration of hydrogen ions. To characterize the reaction of a medium, a hydrogen index, denoted pH, is used. (The hydrogen index is the logarithm of the concentration of hydrogen ions with the opposite sign.) For distilled water, the pH value is 7.07, an acidic environment is characterized by a pH of less than 7.07, and an alkaline environment is characterized by a pH of more than 7.07. The hydrogen index of human blood at a body temperature of 37°C is 7.36. The active blood reaction is slightly alkaline. Even minor changes in the pH value of the blood disrupt the functioning of the body and threaten its life. At the same time, in the process of life, as a result of metabolism in tissues, significant amounts of acidic products are formed, for example, lactic acid during physical work. With increased breathing, when a significant amount of carbonic acid is removed from the blood, the blood can become alkaline. The body usually quickly copes with such pH deviations. This function is performed by buffer substances found in the blood. These include hemoglobin, acid salts of carbonic acid (bicarbonates), salts of phosphoric acid (phosphates) and blood proteins.
The constancy of the blood reaction is maintained by the activity of the lungs, through which carbon dioxide is removed from the body; excess substances that have an acidic or alkaline reaction are excreted through the kidneys and sweat glands.
Blood plasma proteins
Of the organic substances in plasma, proteins are of greatest importance. They ensure the distribution of water between the blood and tissue fluid, maintaining water-salt balance in the body. Proteins participate in the formation of protective immune bodies, bind and neutralize toxic substances that have entered the body. Plasma protein fibrinogen is the main blood clotting factor. Proteins give the blood the necessary viscosity, which is important for maintaining a constant level of blood pressure.
sohmet.ru
Practical work No. 3 Human red blood cells in isotonic, hypotonic and hypertonic solutions
You need to take three numbered slides. Apply a drop of blood to each glass, then add a drop of physiological solution to the drop on the first glass, distilled water on the second, and 20% solution on the third. Cover all drops with coverslips. Let the preparations stand for 10–15 minutes, then examine them under high magnification with a microscope. In saline solution, red blood cells have the usual oval shape. In a hypotonic environment, red blood cells swell and then burst. This phenomenon is called hemolysis. In a hypertonic environment, red blood cells begin to shrink, wrinkle, losing water.
Draw red blood cells in isotonic, hypertonic and hypotonic solutions.
Performing test tasks.
Samples of test tasks and situational tasks
chemical compounds that are part of the plasma membrane and, being hydrophobic, serve as the main barrier to the penetration of water and hydrophilic compounds into the cell
polysaccharides
IF HUMAN ERYTHROCYTES ARE PLACED IN A 0.5% NaCl SOLUTION, THEN WATER MOLECULES
will move predominantly into the cell
will move primarily out of the cell
will not move.
will move in equal numbers in both directions: into and out of the cell.
In medicine, gauze dressings moistened with a NaCl solution of a certain concentration are used to cleanse wounds of pus. FOR THIS PURPOSE THE SOLUTION IS USED
isotonic
hypertensive
hypotonic
neutral
a type of transport of substances across the outer plasma membrane of a cell that requires ATP energy
pinocytosis
diffusion through the channel
facilitated diffusion
simple diffusion
Situational task
In medicine, gauze dressings moistened with a NaCl solution of a certain concentration are used to cleanse wounds of pus. What NaCl solution is used for this purpose and why?
Practical lesson No. 3
The structure of eukaryotic cells. Cytoplasm and its components
The eukaryotic type of cellular organization with its high orderliness of vital processes both in the cells of unicellular and multicellular organisms is due to the compartmentalization of the cell itself, i.e. dividing it into structures (components - nucleus, plasmalemma and cytoplasm, with its inherent organelles and inclusions), differing in details of structure, chemical composition and division of functions between them. However, at the same time, various structures interact with each other.
Thus, the cell is characterized by integrity and discreteness as one of the properties of living matter; in addition, it has the properties of specialization and integration in a multicellular organism.
The cell is the structural and functional unit of all life on our planet. Knowledge of the structure and functioning of cells is necessary for the study of anatomy, histology, physiology, microbiology and other disciplines.
continue the formation of general biological concepts about the unity of all life on Earth and the specific characteristics of representatives of various kingdoms, manifested at the cellular level;
study the features of the organization of eukaryotic cells;
study the structure and function of cytoplasmic organelles;
be able to identify the main components of a cell under a light microscope.
To develop professional competencies, a student must be able to:
distinguish eukaryotic cells and give their morphophysiological characteristics;
distinguish prokaryotic cells from eukaryotic cells; animal cells from plant cells;
find the main components of a cell (nucleus, cytoplasm, membrane) under a light microscope and on an electronogram;
differentiate various organelles and cell inclusions on electron diffraction patterns.
To develop professional competencies, a student must know:
features of the organization of eukaryotic cells;
structure and function of cytoplasmic organelles.
studfiles.net
Blood osmotic pressure
Osmotic pressure is the force that forces a solvent (for blood, water) to pass through a semi-permeable membrane from a solution with a lower concentration to a more concentrated solution. Osmotic pressure determines the transport of water from the extracellular environment of the body into cells and vice versa. It is caused by osmotically active substances soluble in the liquid part of the blood, which include ions, proteins, glucose, urea, etc.
Osmotic pressure is determined by the cryoscopic method, using the determination of the freezing point of blood. It is expressed in atmospheres (atm.) and millimeters of mercury (mmHg). The osmotic pressure is calculated to be 7.6 atm. or 7.6 x 760 = mmHg. Art.
To characterize plasma as the internal environment of the body, the total concentration of all ions and molecules contained in it, or its osmotic concentration, is of particular importance. The physiological significance of the constancy of the osmotic concentration of the internal environment is to maintain the integrity of the cell membrane and ensure the transport of water and solutes.
Osmotic concentration in modern biology is measured in osmoles (osm) or milliosmoles (mosm) - a thousandth of an osmole.
Osmol is the concentration of one mole of a non-electrolyte (for example, glucose, urea, etc.) dissolved in a liter of water.
The osmotic concentration of a non-electrolyte is less than the osmotic concentration of an electrolyte, since electrolyte molecules dissociate into ions, as a result of which the concentration of kinetically active particles increases, which determine the value of the osmotic concentration.
The osmotic pressure that a solution containing 1 osmol can develop is 22.4 atm. Therefore, osmotic pressure can be expressed in atmospheres or millimeters of mercury.
The osmotic concentration of plasma is 285 - 310 mOsm (on average 300 mOsm or 0.3 osm), this is one of the most stringent parameters of the internal environment, its constancy is maintained by the osmoregulation system with the participation of hormones and changes in behavior - the emergence of a feeling of thirst and the search for water.
The part of the total osmotic pressure due to proteins is called colloid osmotic (oncotic) pressure of blood plasma. Oncotic pressure is 25 - 30 mm Hg. Art. The main physiological role of oncotic pressure is to retain water in the internal environment.
An increase in the osmotic concentration of the internal environment leads to the transition of water from the cells into the intercellular fluid and blood, the cells shrink and their functions are impaired. A decrease in osmotic concentration leads to the fact that water passes into the cells, the cells swell, their membrane is destroyed, and plasmolysis occurs. Destruction due to swelling of blood cells is called hemolysis. Hemolysis is the destruction of the membrane of the most numerous blood cells - red blood cells with the release of hemoglobin into the plasma, which turns red and becomes transparent (lacquered blood). Hemolysis can be caused not only by a decrease in the osmotic concentration of the blood. The following types of hemolysis are distinguished:
1. Osmotic hemolysis develops with a decrease in osmotic pressure. Swelling occurs, then destruction of red blood cells.
2. Chemical hemolysis - occurs under the influence of substances that destroy the protein-lipid membrane of red blood cells (ether, chloroform, alcohol, benzene, bile acids, saponin, etc.).
3. Mechanical hemolysis - occurs with strong mechanical effects on the blood, for example, strong shaking of an ampoule with blood.
4. Thermal hemolysis - caused by freezing and thawing of blood.
5. Biological hemolysis - develops from transfusion of incompatible blood, from the bites of some snakes, under the influence of immune hemolysins, etc.
In this section we will dwell in more detail on the mechanism of osmotic hemolysis. To do this, let us clarify such concepts as isotonic, hypotonic and hypertonic solutions. Isotonic solutions have a total ion concentration not exceeding 285-310 mmol. This may be 0.85% sodium chloride solution (often called "saline" solution, although this does not completely reflect the situation), 1.1% potassium chloride solution, 1.3% sodium bicarbonate solution, 5.5% glucose solution and etc. Hypotonic solutions have a lower ion concentration - less than 285 mmol. Hypertensive, on the contrary, is large - above 310 mmol. Red blood cells, as is known, do not change their volume in an isotonic solution. In a hypertonic solution, they reduce it, and in a hypotonic solution, they increase their volume in proportion to the degree of hypotension, up to the rupture of the red blood cell (hemolysis) (Fig. 2).
Rice. 2. The state of erythrocytes in NaCl solutions of various concentrations: in a hypotonic solution - osmotic hemolysis, in a hypertonic solution - plasmolysis.
The phenomenon of osmotic hemolysis of erythrocytes is used in clinical and scientific practice to determine the qualitative characteristics of erythrocytes (method for determining the osmotic resistance of erythrocytes), the resistance of their membranes to destruction in a studded solution.
Oncotic pressure
The part of the total osmotic pressure due to proteins is called colloid osmotic (oncotic) pressure of blood plasma. Oncotic pressure is 25 - 30 mm Hg. Art. This represents 2% of the total osmotic pressure.
Oncotic pressure is largely dependent on albumins (80% of oncotic pressure is created by albumins), which is due to their relatively low molecular weight and large number of molecules in plasma.
Oncotic pressure plays an important role in the regulation of water metabolism. The greater its value, the more water is retained in the vascular bed and the less it passes into the tissues and vice versa. When the concentration of protein in the plasma decreases, water is no longer retained in the vascular bed and passes into the tissues, and edema develops.
Regulation of blood pH
pH is the concentration of hydrogen ions, expressed as the negative logarithm of the molar concentration of hydrogen ions. For example, pH=1 means that the concentration is 101 mol/l; pH=7 - concentration is 107 mol/l, or 100 nmol. The concentration of hydrogen ions significantly affects enzymatic activity and the physicochemical properties of biomolecules and supramolecular structures. Normally, the pH of the blood corresponds to 7.36 (in arterial blood - 7.4; in venous blood - 7.34). The extreme limits of blood pH fluctuations compatible with life are 7.0-7.7, or from 16 to 100 nmol/l.
During the metabolic process, a huge amount of “acidic products” are formed in the body, which should lead to a shift in pH to the acidic side. To a lesser extent, alkalis accumulate in the body during metabolism, which can reduce the hydrogen content and shift the pH of the environment to the alkaline side - alkalosis. However, the blood reaction under these conditions practically does not change, which is explained by the presence of blood buffer systems and neuro-reflex regulatory mechanisms.
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Tonicity is... What is Tonicity?
Tonicity (from τόνος - “tension”) is a measure of the osmotic pressure gradient, that is, the difference in the water potential of two solutions separated by a semi-permeable membrane. This concept is usually applied to solutions surrounding cells. Osmotic pressure and tonicity can only be affected by solutions of substances that do not penetrate the membrane (electrolytes, proteins, etc.). Solutions penetrating through the membrane have the same concentration on both sides and, therefore, do not change tonicity.
Classification
There are three options for tonicity: one solution in relation to another can be isotonic, hypertonic and hypotonic.
Isotonic solutions
Schematic representation of a red blood cell in an isotonic solutionIsotonia is the equality of osmotic pressure in liquid media and tissues of the body, which is ensured by maintaining osmotically equivalent concentrations of the substances contained in them. Isotonia is one of the most important physiological constants of the body, provided by self-regulation mechanisms. An isotonic solution is a solution having an osmotic pressure equal to the intracellular one. A cell immersed in an isotonic solution is in an equilibrium state - water molecules diffuse through the cell membrane in equal quantities in and out, without accumulating or being lost by the cell. Deviation of osmotic pressure from the normal physiological level entails a disruption of metabolic processes between blood, tissue fluid and body cells. Severe deviation can disrupt the structure and integrity of cell membranes.
Hypertonic solutions
Hypertonic solution is a solution that has a higher concentration of a substance relative to the intracellular one. When a cell is immersed in a hypertonic solution, it dehydrates - intracellular water comes out, which leads to the cell drying out and shrinking. Hypertonic solutions are used in osmotherapy to treat intracerebral hemorrhage.
Hypotonic solutions
A hypotonic solution is a solution that has lower osmotic pressure relative to another, that is, it has a lower concentration of a substance that does not penetrate the membrane. When a cell is immersed in a hypotonic solution, osmotic penetration of water into the cell occurs with the development of its hyperhydration - swelling followed by cytolysis. Plant cells are not always damaged in this situation; when immersed in a hypotonic solution, the cell will increase turgor pressure, resuming its normal functioning.
Effect on cells
Epidermal cells of Tradescantia are normal and with plasmolysis.
In animal cells, a hypertonic environment causes water to leave the cell, causing cellular shrinkage (crenation). In plant cells, the effects of hypertonic solutions are more dramatic. The flexible cell membrane extends from the cell wall, but remains attached to it in the plasmodesmata region. Plasmolysis develops - the cells acquire a “needle-like” appearance, plasmodesmata practically cease to function due to contraction.
Some organisms have specific mechanisms to overcome environmental hypertonicity. For example, fish living in a hypertonic saline solution maintain intracellular osmotic pressure by actively excreting excess salt they drink. This process is called osmoregulation.
In a hypotonic environment, animal cells swell to the point of rupture (cytolysis). To remove excess water, freshwater fish constantly urinate. Plant cells resist hypotonic solutions well due to their strong cell wall, which provides effective osmolarity or osmolality.
Some drugs for intramuscular use are preferably administered in the form of a slightly hypotonic solution, which allows for better tissue absorption.
see also
- Osmosis
- Isotonic solutions
Osmosis is the movement of water through a membrane towards a higher concentration of substances.
Fresh water
The concentration of substances in the cytoplasm of any cell is higher than in fresh water, so water constantly enters cells in contact with fresh water.
- Erythrocyte in hypotonic solution fills with water to capacity and bursts.
- Freshwater protozoa have a way to remove excess water. contractile vacuole.
- The plant cell is prevented from bursting by its cell wall. The pressure of a water-filled cell on the cell wall is called turgor.
Over-salted water
IN hypertonic solution water leaves the red blood cell and it shrinks. If a person drinks sea water, the salt will enter his blood plasma, and water will leave the cells into the blood (all cells will shrink). This salt will need to be excreted in urine, the amount of which will exceed the amount of seawater drunk.
In plants it occurs plasmolysis(departure of protoplast from the cell wall).
Isotonic solution
Saline solution is a 0.9% sodium chloride solution. Our blood plasma has the same concentration; osmosis does not occur. In hospitals, a solution for drip is made from saline solution.
