What are the main provisions of the teachings of Ch. Darwin?

1. Organisms are changeable. It is impossible to find two completely identical rabbits, wolves, lizards or other animals or plants belonging to the same species.

2. Differences between organisms are, at least in part, inherited.

3. Theoretically, under favorable conditions, any organisms can multiply so much that they are able to fill the Earth, but this does not happen, since many individuals die before they have time to produce offspring.

4. Those organisms that have beneficial properties are more likely to survive than others. Survivors pass these properties on to their offspring. Consequently, these properties are fixed in a series of subsequent generations.

Evidence for Darwin's theory

On what facts did Darwin base the evidence for his theory?

The facts on which Darwin based his evidence for his theory are:

1) island plants and animals differ sharply from closely related species on the continent;

2) related species on different islands differ in appearance, body size, and life habits against the background of diverse habitat conditions;

3) fossil remains of the giant sloth and armadillo were found, significantly larger than their relatives, still inhabiting Central and South America;

4) the preservation of marsupials and oviparous precisely in Australia, where they found themselves in isolation, and died out in other places on the globe;

5) differences between different breeds of the same kind of domesticated animals, which are sometimes even more significant than between different types of wild animals;

6) each organism is able to produce more offspring than it can survive, and only a limited number of them survive and leave their offspring.

Struggle for existence

What facts allow us to talk about the struggle for existence? How does this struggle manifest itself in nature?

Living organisms tend to multiply exponentially and theoretically any organism can fill the Earth very quickly.

In fact, this never happens, because the resources of life are limited and go to only a few - those who can win the struggle for life, or the struggle for existence.

The intraspecific struggle for existence is manifested in different species, primarily in competition for food resources and a sexual partner. As a rule, a direct collision of individuals is prevented by various adaptations, among which marks indicating an individual area should be distinguished: the singing of songbirds, the leaving of odorous secretions, etc. Violation of the boundaries of an individual area is often accompanied by fights. Less common is direct interaction, such as cannibalism.

Variability

What is variability in organisms?

Variability is the property of organisms to acquire new features that distinguish them from other organisms of the same species. Variability affects all the properties of organisms: structural features, color, physiology, behavioral features, etc.

Variability forms

What kinds of variability do you know?

There are two main forms of variability - non-hereditary and hereditary (genetic).

Population hereditary variability

What is population genetic variation? Why does the gene pool of a population change over time?

The hereditary variability of a population is the most important property of this supraorganismal system, which lies in the fact that the population as a whole is capable of acquiring traits that distinguish it from other populations of the same species.

The gene pool is the sum of all genotypes present in a population. It is the most important indicator of the genetic composition of the entire population. The gene pool of a population changes over time due to the variability of genotypes and as a result of natural selection.

Adaptive changes in the gene pool

What facts can serve as proof of the adaptive (adaptive) nature of changes in the gene pool?

One example proving the adaptive nature of changes in the gene pool of a population is the so-called industrial mechanism in the birch moth.

The color of the wings of this butterfly imitates the color of the birch bark, on which these dusky butterflies spend daylight hours.

In populations living in industrial areas, over time, the previously extremely rare dark butterflies began to dominate, while white ones, on the contrary, became rare. In the gene pools of these populations, the frequency of alleles that determine the corresponding protective coloration has changed.

Evolutionary changes in the gene pool

What changes in the gene pool allow us to draw a conclusion about the evolutionary changes taking place in the population?

The evolutionary changes taking place in a population can be judged by changes in the external structure of organisms, the characteristics of their behavior and lifestyle, and, ultimately, by the better adaptation of the population to given environmental conditions. The ongoing changes are the result of an increase in the frequencies of some genes in the gene pool and a decrease in the frequencies of others.

genetic balance

What is genetic balance? Under what conditions is it possible?

Genetic equilibrium - the state of the gene pool of a population, in which there is a constancy of allele frequencies of various genes. It is possible only under conditions of weak pressure of natural selection, when the population lives in isolation.

Factors of violation of genetic balance

What factors cause genetic imbalance in conditions when natural selection does not act?

In addition to natural selection, the following factors lead to the violation of the genetic balance in the population:

1) non-random selection of partners during mating, characteristic of some animals;

2) the loss of some rare species, for example, due to the death of their carriers (the smaller the population, the greater the impact of random factors on its gene pool);

3) division of the population into two unequal parts by some unexpected natural or artificial barriers;

4) the transfer by the population of any catastrophe that led to the death of most of it.

The struggle for existence and its forms

1. What is the essence of Mendel's laws?
2. What are the main provisions of the evolutionary teachings of Darwin.

Thinking about mechanisms and driving forces evolution, Charles Darwin came to the concept of the struggle for existence. This is one of the central concepts of the theory of evolution. Charles Darwin drew attention to the fact that all living beings have the ability of practically "limitless" reproduction. A female roundworm, for example, produces 200 thousand eggs per day, a gray rat 5 litters per year, an average of 8 rat pups reaching puberty by the age of three months, in one fruit of cuckoo tears there are at least 186,000 seeds. The ability to reproduce rapidly leads to important consequences: with the growth of the intensified competition for resources, the probability of the emergence of new ones increases. mutations and a “pressure of life” is created, as a result of which there is a struggle for existence. Ch. Darwin repeatedly emphasized that the struggle for existence is not reduced to a direct fight, it is a complex and diverse relationship of organisms within the same species, between different species and with inorganic nature. “I must warn,” Darwin wrote, “that I use this term in a broad, metaphorical sense ... About two dogs or wolves in a time of famine, one can rightfully say that they are fighting each other for and thereby for life. But about a plant growing on the "edge of the desert, we can say that it is fighting for life against drought." The reward in the struggle for existence is life and the possibility of its continuation in successive generations.

Forms of the struggle for existence.

Darwin distinguished three forms of the struggle for existence: intraspecific, interspecific, and the struggle against adverse conditions of inorganic nature. The most intense of them is intraspecific struggle. A vivid example of intraspecific struggle is the competition between coniferous forest trees of the same age. The tallest trees, with their widely spread crowns, intercept the bulk of the sun's rays, and their powerful root system absorbs dissolved minerals from the soil to the detriment of weaker neighbors. Intraspecific struggle is especially aggravated with increasing density populations for example, with an abundance of chicks in some species of birds (many species of gulls, petrels), the stronger ones push the weaker ones out of the nests, dooming them to death from predators or starvation.

Interspecific struggle can manifest itself in various forms, for example, in the form of competition (competition) for food or other resources, or in the form of the unilateral use of one species by another. An illustrative example of competition for food is provided by the predators of the African savannas (cheetahs, lions, hyenas, hyena dogs, etc.), which often take away caught and killed prey from each other. Often, attractive habitats are the object of competition. For example, in the struggle for a place in human settlements, the gray rat, stronger and more aggressive, eventually replaced the black rat, which is currently found only in forest areas or in deserts. The American mink brought to Europe replaces the native European species. The muskrat (a native of North America) has intercepted some of the resources previously used by native species, such as the Russian muskrat. In Australia, the common bee brought from Europe has supplanted the small, stingless native bee.

The third form of the struggle for existence is the struggle against unfavorable external conditions. Factors of inanimate nature have a direct and indirect influence on the evolution of living things. Plants in the desert are said to be "drought-fighting", referring to the development of numerous adaptations that help them extract water and nutrients from the soil (special root system) or reduce transpiration rate (special leaf structure). The conditions of the inorganic world have a significant influence on the evolution of organisms, not only in themselves, their influence can strengthen or weaken intra- and interspecies relationships. With a lack of territory, heat or light, intraspecific struggle intensifies, and vice versa, with an excess of resources necessary for life, it weakens.

Struggle for existence. Forms of struggle for existence: intraspecific, interspecific, with unfavorable conditions.

1. List the main forms of the struggle for existence.
2. What facts allow us to talk about the "pressure of life"?
3. Why is intraspecific struggle the most intense form of struggle for existence?

Based on your own observations, prepare examples that describe the struggle for existence between organisms: a) of the same species; b) different types.

Kamensky A. A., Kriksunov E. V., Pasechnik V. V. Biology Grade 10
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High blood pressure is a symptom of various diseases. It does not always give painful sensations, and a person may not be aware of the presence of hypertension. At the same time, prolonged pressure often forms serious complications. They don't call him the "silent killer" for nothing. Preservation of increased blood pressure inside the vessels forms deadly pathologies, causes strokes and heart attacks.

In this article, we will look at how high pressure is formed and why is it dangerous? Which of the complications have the most unfortunate consequences? And why is it necessary to pay attention to pressure and periodically measure its value?

High pressure readings

Normal pressure is considered to be the figure 120/80 mm Hg. Art. This is an average rate that is valid for most average healthy people. Normal indicators are also considered, the numbers of which exceed the average or do not reach them by 10-20 units. Therefore, the norm is blood pressure from 100/70 mm (for a person of small stature or thin build) and up to 140/90 mm (for a tall large person).

High pressure is called, the indicators of which exceed 140/90 mm Hg. Art. It is with these numbers that the countdown of pathology and the formation of complications begin.

High blood pressure can be slightly or very high. According to its indicators, three degrees of hypertension are distinguished - the so-called mild, moderate and severe. They differ not only in the magnitude of blood pressure, but also in the consequences of the disease (complications) and the speed of their formation.

Conventionally, hypertension is divided into the following stages:

• The first 140-160 / 90-100 mm - mild hypertension;
• The second 160-180 / 100-110 mm - medium or moderate hypertension;
• The third more than 180 / 110 mm - severe hypertension, the most dangerous increase in pressure.

And now let's turn to what changes occur in the body with an increase in pressure. Why is high blood pressure dangerous, and why are the highest numbers the most undesirable for a person?

What high blood pressure is considered dangerous?

A slight increase in pressure (up to 160 mm) forms a pathology for a very long time. Therefore, hypertension of the first degree is not considered dangerous. It is not accompanied by pathological changes in the heart, blood vessels, brain, kidneys, and therefore doctors say that first-degree hypertension has no risks and is not accompanied by pathological changes in organs.

A moderate increase in pressure (up to 180 mm) forms internal pathologies for several years. So, due to stable blood pressure above 160 mm, hypertrophy of the left ventricle of the heart and narrowing of the retinal arteries (which causes visual impairment) are formed. Complications of moderately high pressure - on the face.

The third severe degree of hypertension, pressure above 180 mm Hg. Art. accompanied by a strong narrowing of the arteries and blood vessels, loss of their elasticity and rupture. Therefore, the main danger of the third stage is hemorrhage. Pressure above 180 is the most dangerous. It often leads to rupture of blood vessels. What forms a heart attack in the heart muscle, and a stroke in the brain cells.

Doctors insist on the need to reduce pressure, which exceeds even 140/90. It must be understood that short-term jumps above 140 (for systolic) and 90 (for diastolic) do not bring tangible harm, except for unpleasant sensations.

Such jumps are possible with physical exertion, slight stress, atmospheric pressure drops. But a long stay of the body in a state of hypertension is harmful. It forms a number of pathological processes and destructive changes in organs and tissues.

How pressure rises

Blood pressure controls the movement of blood through the vessels. It is created by contractions of the heart muscle and the tone of the vascular walls. Thanks to pressure, all human organs are supplied with blood, oxygen, and nutrients.

An increase in pressure above normal occurs when the existing blood flow weakens. Its speed and amount of blood become insufficient to fully supply the body with oxygen. And then regulatory mechanisms increase blood pressure.

A pathological increase in pressure occurs if:

Thus, an increase in pressure occurs due to disturbances in the functioning of the circulatory or vascular systems. It is a necessary condition for survival. Increased pressure is necessary for the body to push through viscous blood, or to normalize the speed of blood flow through the vessels.

Thanks to the increase in pressure, the cells of the body continue to receive the necessary nutrition and oxygen. But those organs that work “for wear and tear”, after a while they themselves lose their tone, elasticity, and the ability to adequately respond to environmental changes. This creates conditions for the development of further pathologies - the so-called complications.

What suffers in the first place with a chronic increase in blood pressure in a person?

target organs

Those human organs that, when pressure increases, perform increased work and carry an additional load, suffer from hypertension in the first place. These include the human heart and blood vessels. They are called "target organs", since it is they that form various pathologies in them.

Also, the target organs include those organs, the condition of which is more dependent on blood supply than others. This is the human brain and excretory organs - the kidneys. What happens in the cells of the heart, brain and kidneys with a frequent increase in pressure?

Why is high blood pressure dangerous for the heart?

The heart is the main motor of the human body and circulatory system. With increased pressure, it works more often and forms more powerful blood emissions. With prolonged overstrain of the heart muscles, the following cardiac pathologies are formed:

1. Hypertrophy of the left ventricle (from increased contractions to push blood and create pressure). It is expressed in the thickening of the heart wall. Such thickening requires an increased blood supply to the heart, which becomes impossible with the development of hypertension. This initiates cardiac arrhythmias, necrosis of cardiac tissues and myocardial infarction.
2. Depletion of the tissue of the left ventricle of the heart - occurs due to constant stress and, as a result, lack of nutrition.
3. Heart failure - is formed due to the fact that overstrain of the heart leads to insufficient rest, relaxation. Fatigue is formed, which does not allow the heart muscles to fully contract (which is called chronic heart failure).

Blood vessels form the main channel of blood flow. With chronic high blood pressure, the vessels are tense, often spasmodic and covered with cholesterol plaques. The constant overstrain of the vascular walls does not give them the opportunity to relax. This leads to malnutrition and partial replacement of the muscle wall with connective tissue.

If the replacement of muscle walls with connective tissue occurs in the organs of vision, then vision gradually deteriorates until it is completely lost. If the processes occur in the limbs, then atherosclerosis of the vessels of the arms and legs is formed, the limbs become cold.

If pathological changes occur in the vessels of the brain, then there is a violation of cerebral circulation, constant headaches, flies before the eyes, dizziness, sudden falls are formed. But this is not a complete list of complications that form in human vessels at high pressure.

The most dangerous complication of hypertension is stroke and heart attack. They accompany ruptures of thinned degraded vessels in the brain or heart. These complications cause necrosis (death) of brain and heart tissues.

They are dangerous with a lethal outcome (death). That's why you should not give a damn about the constant high blood pressure. Even average moderate hypertension creates conditions for the degradation of the vascular walls. What makes it possible to develop a stroke or heart attack with a possible jump in pressure.

Why is high blood pressure dangerous for the kidneys

Gradual vascular sclerosis causes a number of pathological changes in the kidneys. The most dangerous of them is a violation of the excretory function, in which toxins accumulate in the blood. The reason for this is the so-called microalbuminuria or leakage of protein through the renal filter. Such a pathology is formed with increased pressure. As a result, protein is detected in urine tests.

A slight increase in pressure: why is it dangerous?

A sudden and sharp increase in pressure - by 20 or more units, brings a number of unpleasant sensations. Headache and dizziness, flies flash in the eyes, the face turns red, there is a feeling of fullness in the head and eyes.

A sharp jump in blood pressure increases blood flow and makes the heart beat faster. The pulse quickens and tachycardia appears. Why is sudden high blood pressure dangerous?

For a healthy person, a short-term increase in pressure, even to high values, is not dangerous. Its vessels will adequately respond to any increase, the elastic walls are stretched and compensate for the accelerated blood flow.

An increase in pressure is dangerous for those people whose vessels are spasmodic and sclerotic. In this case, they are not able to respond adequately - to stretch and skip the increased blood flow. Which often leads to their break.

Small fluctuations in blood pressure do not have any consequences if they are short-lived. In this case, they do not have time to form pathological changes and are poorly felt by a person.

Small increases in pressure become painful with their constant presence. If a person's pressure consistently exceeds the norm (more than 140/90 mm), then this creates conditions for the development of vascular pathology.

It also indicates a malfunction in the body, the accumulation of toxins or constant stress. That also requires attention and treatment.

Elevated systolic and diastolic pressure: which is more dangerous?

The first digit in the measurement of pressure indicates its value at the time of contraction of the heart muscle (when pushing blood through the vessels). It is called the upper or systolic. The first digit shows the maximum pressure, its value is the most critical for a person.

The second number shows the so-called dystolytic or lower pressure, which is maintained by the walls of the vessels between contractions of the heart. It is always lower than systolic by 40-50 units.

In most cases of high blood pressure, both numbers are higher than normal. For example, 140/90 or 180/100 are indicators of high blood pressure of varying degrees.

However, there are situations in which the pressure rises not correlatively, but mainly only the upper or only the lower number. What is the danger of increasing individual blood pressure numbers?

High first digit: why is it dangerous?

Upper systolic pressure is determined by the state of the heart muscle, the frequency and strength of its contraction at the time of blood ejection. Doctors say that the upper pressure reflects the state of the myocardium, and they call it cardiac. High upper pressure with normal low indicates cardiac pathology.

In addition, with high upper pressure against the background of normal low pressure, a large difference is formed between the indicators. In medicine, it is called pulse pressure.

Lower diastolic pressure is determined by the state of the vessels. In between heartbeats (emissions of blood from the heart into the bloodstream), the tone of the vascular walls maintains the overall pressure in the circulatory system. Basically, the lower pressure is formed by peripheral arteries, the most distant from the heart muscle. These are the thinnest vessels and capillaries through which blood enters the tissues.

A high indicator of lower pressure can signal a poor condition of the vessels, their low elasticity, and the presence of cholesterol deposits. It is also formed after drinking alcohol, with hypothermia, during stress.

On a note: with hypothermia, prolonged exposure to cold, blood circulation in the peripheral vessels is reduced - the limbs freeze. This causes an increase in the lower pressure figure - the body tries to restore blood circulation in the fingers and toes by increasing vascular tone.

In addition, lower blood pressure increases with an increase in blood volume, with the so-called saline hypertension (when a person has high blood pressure due to eating too many foods with salt preservatives).

Note: beer drinkers suffer from a persistent increase in diastolic pressure. This drink causes fluid retention in the body and an increase in lower blood pressure. Therefore, men are more likely to suffer from high blood pressure than women.

Why is high blood pressure dangerous? High diastolic pressure accompanies atherosclerosis and low vascular elasticity. Therefore, high rates of the second digit indicate a possible rupture of the vascular walls and internal hemorrhages.

In addition, an increase in the second digit of the measured pressure occurs with kidney disease. In renal pathology, this occurs due to the release of renin by the kidneys, which increases the muscle tone of the vessels.

Lower pressure is called vascular and renal. The main danger of its increase is the absence of any painful symptoms in the initial stages of development.

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What determines the level of blood pressure?

Blood, moving through the vessels, exerts pressure on their walls. The presence or absence of a generally accepted normal blood pressure indicator (120/80) is determined by several factors:

• degree of vascular resistance;
• cardiac functionality;
• total blood volume.

Despite the fact that many people do not consider deviations from standard values ​​to be a pathology at all, since all systems and organs work as they should, physicians have known for a long time what dangerously low blood pressure is.

What does blood pressure say?

In addition to the external manifestations of this condition in the form of general weakness of the body, shortness of breath, dizziness and loss of coordination, hypotension can cause more serious consequences. The first alarm signals received by the patient must necessarily serve as a reason for seeking advice from specialists. In addition, if the danger of low pressure has receded, which quite often lulls the vigilance of patients, this does not mean at all that a recurrence is not expected.

By itself, blood pressure is an indicator that can indicate violations in the work of such vital organs as the lungs, heart, and circulatory system. This predetermines the need for regular pressure measurements, especially since its value is not static and constant. You can find out why low blood pressure is dangerous in a person by familiarizing yourself with the characteristics of blood circulation.

Systolic and diastolic blood pressure in humans

As you know, when measuring the pressure of a patient, doctors draw conclusions about his condition in two quantities:

1. Systolic pressure is the upper indicator showing the level of pressure during the ejection of blood into the aorta.
2. Diastolic pressure - the lower indicator, fixes the moment of blood entering the vena cava.

If the first criterion is able to determine the blood pressure in the process of its transportation through the vessels from the heart to other vital organs, then the second one indicates its value in the intervals between heart contractions. At the moment of short-term relaxation of the myocardium, blood pressure is measured.

What pressure is considered normal?

Probably everyone knows that 120/80 is the most familiar indicator, which is considered an unconditional norm. Although recently, experts have begun to assert with greater confidence that the most comfortable blood pressure for a person is 115/75.
It is difficult to determine what critical low pressure is dangerous for a person, as well as to find out the norm for the same person. The fact is that blood pressure, at which the patient's well-being is satisfactory, is a purely individual value. It is almost impossible to establish with accuracy that this particular indicator is optimal for a particular person.

What are the characteristics of low blood pressure?

Meanwhile, doctors around the world consider BP 90/60 unequivocally low. Whether low pressure is dangerous for a person with such indicators depends largely on what he feels at that moment, what the symptoms are.

The most common manifestations of hypotension, in which the thought of pathology immediately arises, are:

• Regular drowsiness, lethargy, rapid fatigue. Any activity (physical, mental) leads to instant fatigue, after rest and a night's sleep, relief, as a rule, does not occur.
• Headaches (cephalgia with reduced pressure often occupies the occipital and temporal lobes; the nature and intensity of the pain syndrome is similar to migraine: monotonous, pulsating or dull).
• Nausea, vomiting.
• Frequent dizziness, short-term loss of consciousness, impaired coordination of movements.
• Irritability, inattention, distraction.

Is low blood pressure dangerous? This can be determined based on the above symptoms. Such signs of hypotension can deliver great discomfort and suffering to the patient. How to avoid it? You can prevent the development of pathology, especially if you are not at risk. But even if this is not the case, it is still possible to help yourself. The reasons why a systolic or diastolic blood count may fall are presented below.

Causes of low diastolic pressure

With reduced diastolic pressure, common signs of hypotension appear in the form of impotence, dizziness and nausea. The ideal indicator is the one that is less than systolic by 30-40 mm Hg. Art. This leads to the establishment of a common norm of 120/80 with a difference of 40 mm Hg. Art. The diastolic value is considered low if the discrepancy between it and the systolic indicator is more than 50 units.

Many patients do not immediately identify themselves with low blood pressure, regularly suffering from symptoms of weakness. Even fewer people, having discovered that they have a disease, go to the doctor with this problem, because not everyone knows how dangerous low blood pressure is in a person, especially if such a deviation does not cause significant trouble and inconvenience. A person's well-being at low lower pressure depends on the causative factors that provoked changes in blood circulation. The most common ones are:

• heart failure;
• kidney failure or chronic adrenal disease;
• allergic reactions;
• pain shock;
• thyroid disorders.

How to prevent hypotension?

It is the low lower pressure that deserves special attention, the reasons for which are indicated above. How to increase the diastolic rate, every person should know. In the end, such knowledge may one day be useful to someone else.

Following the rules of a healthy lifestyle, as well as sufficient time in the fresh air and moderate physical activity, is the main secret to the normalization of diastolic blood pressure. Regular and full night sleep for 7-8 hours is undoubtedly also an important guarantee of excellent health. But taking medication with low diastolic pressure is a serious step that is best done together with your doctor.

What causes low diastolic pressure?

What is the danger of low diastolic pressure in a person, if its indicator is able to drop even to the level of 40 mm Hg. Art., interesting to all patients with hypotension. Feeling bad is not everything. The fact is that reduced blood pressure does not allow delivering the necessary amount of blood to the heart and brain, and with it oxygen. Hypoxia of these vital organs is the main threat posed by low pressure in the blood vessels. Such a complication as impaired peripheral circulation and cardiogenic shock is a direct consequence of oxygen starvation.

Fainting and stroke are also very likely to develop at critical levels of lower (diastolic) pressure. In addition, a radical restructuring of the structure of the arteries due to the long course of hypotension ultimately leads to the transition of the disease to a more dangerous form of cardiovascular disease - hypertension. In this form, the disease is much more severe.

Causes of Low Systolic Pressure

Diastolic indicators below the norm indicate the possible development of serious pathological processes, primarily from the cardiovascular system. Meanwhile, low upper blood pressure is often associated with other causes, including:

• tachycardia, arrhythmia, bradycardia (heart rhythm disturbances);
• pathological features of the functioning of the heart valve;
• diabetes;
• first trimester of pregnancy;
• excessive physical activity.

The systolic indicator gives detailed information about the intensity with which the cardiac "pump" pushes the blood out. Within the normal range, its value is about 110-120 mm Hg. Art. It is possible to understand what low pressure is dangerous for a person and how great the threat is by critical indicators of both diastolic and systolic indicators. With extremely low blood pressure, the patient often loses consciousness. With systolic 60 mm Hg. Art. gradually loses touch with reality, it becomes cloudy in the eyes, the legs become "cotton". It is important to have time to call someone for help while it is possible.
To help the patient, it is necessary to lay him in such a horizontal position that the legs are higher than the level of the head.

The threat of low systolic pressure

The lowest pressure in a person is considered critical when its upper values ​​are in the range of 40-60 mm. rt. Art. The patient is already unconscious, and if such pressure remains for 7-8 minutes or more, then the person can leave this world. The heart rate also drops to a minimum and can be 45-60 beats per minute. An emergency call for an ambulance and the arrival of a team of doctors will give the patient a chance for recovery. However, the consequences of the state he endured can leave an indelible mark on his life until the end of his days.

Danger for a pregnant woman

The danger of low pressure in systolic values ​​is present during pregnancy. This is due to hormonal changes in the body. An acceptable decrease in the upper indicators is considered to be a decrease to 10 mm Hg. Art., and lower - up to 15 units. Blood pressure in pregnant women generally reaches its minimum at 22-24 weeks.

Such a decrease is not considered dangerous either for the fetus or for the expectant mother. Meanwhile, fainting is a common symptom of hypotension in pregnant women. Loss of consciousness often leads to falls, which is a potential threat to the baby. Dehydration, which is often diagnosed in pregnant women, can also provoke a decrease in blood pressure.

Classification of hypotension

Low blood pressure is divided into several types:

1. Orthostatic lowering of arterial pressure. Most often occurs with a sharp change in body position (with a sharp rise), when blood flow to the limbs increases, and the heartbeat does not increase. It is characterized by concomitant attacks of dizziness, loss of coordination, in rare cases even consciousness. It is this type of hypotension that is often found in pregnant women, despite the fact that the elderly are considered the main risk group for the onset of the disease.
2. Postprandial hypotension manifests itself in patients of the older age group after eating.
3. Vegetovascular dystonia is the most common type of hypotonic type of disease. Such a decrease in pressure is observed in patients under hot weather conditions, with overwork, stress, etc. The disease is often found in young people.

Today, everyone should know the dangers of low blood pressure in humans. With a rapid heartbeat and pulse, it is difficult for the heart to pump blood through the vessels, which means that the supply of oxygen to the limbs and organs becomes insufficient. To normalize the pressure, you need to take a contrast shower and carefully massage the body with a special massage brush. You can’t get carried away with such a famous remedy for low pressure as coffee or chocolate: for a one-time relief, this is an excellent solution, but if the decrease in arterial parameters has become regular, you should definitely consult a doctor.

How to normalize low blood pressure?

The specialist will be able to confirm or exclude the diagnosis, prescribe appropriate medications if necessary, and monitor the patient's condition. Self-medication can be life-threatening.

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What pressure indicators are considered low

The answer to the question: how much is low pressure is ambiguous. The generally accepted safe lower limit of normal blood pressure for systolic and diastolic values ​​is 100/60 mm Hg. Art. But in practice, one has to deal with situations when they are much lower, but at the same time a person does not feel any discomfort and leads an active lifestyle.

According to classical concepts, hypotension is accompanied by circulatory disorders in the form of:

This impairs the delivery of nutrients and oxygen to all internal organs, which disrupts their normal functioning. The brain and heart are most vulnerable to hypoxia (oxygen starvation).

Due to the adaptive reactions of the body, a decrease in blood pressure is not always accompanied by signs of microcirculation disorders and oxygen starvation, but only under certain circumstances.

Physiological or pathological hypotension - all individually

If a person's blood pressure is below 100/60 mm Hg. Art. does not cause any symptoms and signs of impaired blood circulation, this can be perceived as a variant of the norm - physiological hypotension. It is an individual feature and is more often observed in young women (from adolescence to 40-45 years) for many years.

Types of arterial hypotension

Therefore, some experts recommend taking 90/60 mm Hg beyond the lower limit of the normal pressure. Art. Whether this is true or not is difficult to judge. After all, it has been established that despite the absence of pathological manifestations, people with persistent hypotension throughout their lives are more susceptible to various diseases: anemia, decreased immunity, neurogenic disorders, arrhythmia. About 85% of them after the age of 45 become hypertensive with a strong increase in pressure, which is resistant to drug treatment.

Eliminating habitual hypotension can be extremely difficult and not always safe. This is due to the fact that all body systems that regulate blood pressure (nervous, autonomic, hormonal) have adapted to keep it at a low level for a long time. They have established such a balance among themselves, in which the body does not experience pronounced changes. If you artificially try to increase the pressure, this balance is destroyed and a hypotensive person develops pronounced disorders even at 100/60 mm Hg. Art., not to mention higher.

Pathological hypotension is considered if it is accompanied by complaints and characteristic disorders. This happens more often in people with normal or high blood pressure, when it drops downward. At the same time, the brain and heart experience oxygen starvation, which is the reason for the main symptoms of hypotension.

Causes of the problem

Low pressure always caused by a violation of the mechanisms of its regulation. In the table they are described with indication of causes and diseases.

Pressure Reducing Mechanisms	Causes and diseases
Decreased amount and volume of blood	Bleeding: gastrointestinal, uterine, wounds
	Dehydration: insufficient intake of water and salt, diarrhea, vomiting, overheating, excessive sweating
Decreased pumping function of the heart	Heart attack, heart failure, arrhythmia, myocarditis, cardiomyopathy
Decreased hormonal activity of the endocrine glands	Thyroid - hypothyroidism
	Adrenal - hypocorticism (Addison's disease)
	Pituitary and hypothalamus
Violation of the nervous regulation of vascular tone	Condition after nervous shocks and psychoses, change in body position (if you get up very abruptly from a lying or sitting position), being in a stuffy, cramped or poorly ventilated room
	Vegetovascular dystonia, hereditary features of the regulation of vascular tone
	Stroke and cerebral hemorrhage, traumatic brain injury, tumor
Redistribution of blood in the body - excessive expansion of small vessels	Poisoning and intoxication against the background of infections, ulcers, injuries and burns, alcohol abuse, work with toxic substances
	Overdose of antihypertensive drugs: Nitroglycerin, ACE inhibitors, diuretics, antispasmodics (no-shpa, dibazol), beta-blockers, calcium inhibitors.
allergic reactions	Household, food allergens, treatment with any medications

Causes of low pressure

The extreme degree of pressure drop (below 80–90/50–60 mm Hg), accompanied by very severe microcirculation disorders, is called shock. He can be:

• hemorrhagic - the result of blood loss;
• cardiogenic - dysfunction of the heart;
• infectious-toxic - poisoning, intoxication;
• traumatic - a consequence of a severe injury;
• anaphylactic - an allergic reaction.

It is important to understand that low blood pressure is not only the result of various pathological processes and influences. A slight hypotension (less than 90/60 mm Hg) that has arisen for one of the possible reasons can cause critical circulatory disorders in the heart and brain, from which the indicators will decrease even more.

Possible symptoms

A person whose pressure has decreased may notice the following symptoms and complaints:

If hypotension is not an independent pathological condition, but just one of the symptoms of various diseases, it is accompanied by other signs characteristic of them (they are described in more detail in the table in the section "algorithm for helping patients").

Patient care algorithm

The first step in treating low blood pressure is to determine what the condition is. If it is urgent, there is no time to think - you need to call an ambulance to such a person (telephone 103) and start first aid before it arrives. In any case, patients should be examined by different specialists: a therapist, a cardiologist, a surgeon, a neuropathologist, an endocrinologist.

By differentially excluding the most dangerous causes of low blood pressure, taking into account the existing symptoms, you can find the true cause. It may take only a few minutes to eliminate it, a surgical operation, or it may be such that treatment will be required throughout life.

The general algorithm for helping in any case of low pressure looks like this:

Click on photo to enlarge

What to pay attention to	Possible causes of hypotension	What to do with low pressure
Blueness, puffiness of the face, shortness of breath, chest pain	Heart attack or pulmonary embolism	Give under the tongue Aspirin (Cardiomagnyl), nitroglycerin (if the pressure is at least 90/60)
Hematemesis, black stool	Stomach or intestinal bleeding	Cold on the stomach, hemostatic drugs (Etamzilat, Dicinon, Sangera), Omez
Brain signs (arm and leg weakness, loss of speech and vision, facial twisting)	Stroke, hemorrhage, traumatic brain injury, tumor, inflammation of the brain	Do not lower your head, lay it on its side, impose cold, make sure that the person does not choke when vomiting
Periodic or sudden episodes of low blood pressure without any additional manifestations	Vegetovascular dystonia, hormonal imbalance, abrupt change in body position, overheating, stressful situations	Provide peace, give strong coffee or drugs to drink: citramon, caffeine, cordiamine. If there is no effect - injections Dexamethasone, Prednisolone
Constantly low pressure	If there are no complaints - body features	Treatment by a specialist, general tonic drugs for long-term use (months): Eleutherococcus, Tonginal, Pantocrine.
	The presence of complaints - endocrine or neurovegetative disorders
Very pronounced (less than 80-90 / 50-60) acute hypotension that violates the general condition	Any type of shock, including anaphylactic shock (allergy)	General measures in combination with intravenous administration of drugs:

In all cases of a sudden drop in blood pressure, be sure to call an ambulance (telephone 103). Behind this symptom, a dangerous disease can be hidden!

Forecast of treatment effectiveness

If a decrease in pressure is a symptom of severe emergency diseases, only specialists in a hospital should increase it. In this case, the prognosis is unpredictable (50% of patients in a state of shock die). Habitual causeless hypotension does not pose any danger to life, but in 60–70% it cannot be eliminated, despite treatment.

Reduced blood pressure caused by chronic diseases of the internal organs and hormonal deficiency normalizes on its own against the background of their treatment. Periodic episodes of mild hypotension against the background of vegetovascular dystonia, changes in body position, weather sensitivity and other factors are best treated and least dangerous.

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Signs and causes of low blood pressure

Each person's body is unique. Therefore, it is impossible to talk about strict norms of high or low pressure. There are only average indicators that indicate possible negative changes within the framework of such an organism function.

What indicators on the tonometer are considered low for different groups of people?

However, there are people for whom the norm is much lower than the generally accepted one (that is, for some people, the initial “working” pressure is lower than 120 to 80). This is noted within the framework of heredity, and often a person with congenital low pressure does not feel sick and does not have any additional complaints. A chronic condition usually does not pose any threat to health and life, some doctors tend to believe that such people, on the contrary, are among the long-livers.

Why does pressure drop?

Changes in indicators on the tonometer occur due to the processes occurring inside the body associated with the work of the cardiovascular system and the nervous system.

As part of this, the following grounds stand out:

1. a change in the volume of blood in the body, which is characteristic of prolonged bleeding of varying strength, dehydration; due to a decrease in the amount of blood, pressure also decreases;
2. slowing down of contractions of the heart and a decrease in the strength of these contractions; the less often and weaker the heart pushes out blood, the lower the pressure becomes; this can manifest itself, for example, due to a long period of rest;
3. poor or incorrect functioning of nerve endings, which are considered a compensatory mechanism and try to control pressure stability by sending impulses to the brain; when the work of these nerve fibers is disrupted due to internal or external influences, a failure occurs;
4. sharp and strong narrowing, contraction of blood vessels; when the blood vessels are significantly compressed, they receive an insufficient amount of blood, the person's pressure drops.

All these physiological bases can appear both independently and act in an alliance.

The main causes of low pressure are distinguished:

• concomitant physiological diseases, in which hypotension is a symptom;
• overwork, lack of sleep, prolonged nervous excitement, chronic fatigue syndrome, insomnia, stress;
• depression;
• starvation, malnutrition, dehydration; low blood sugar can also provoke arterial hypotension;
• lack of oxygen;
• taking certain medications and addicting to various sedatives, soothing teas;
• the predominance in the diet of foods that can lower blood pressure;
• long sleep, minimal physical activity;
• infectious blood diseases, serious injuries, bleeding with various causes;
• pregnancy;
• intoxication;
• lack of vitamins, microelements in the body;
• change of climatic zones and time zones.

However, low pressure should be of concern only if unpleasant symptoms are added to the numbers on the tonometer that do not allow a person to function normally.

Signs of low blood pressure

1. Dizziness, dizziness, fainting.
2. Headache, especially in the morning. Localization can be different: in the parietal and temporal lobes, in the back of the head, migraine-like pain, a feeling of squeezing in the forehead area. Painful sensations can be prolonged, dull or pulsating, similar to severe spasms, point.
3. Darkening in the eyes, "flies" before the eyes, narrowing the field of view to a small point, defocused vision. Especially often this manifests itself with a sharp change in body position, then it makes sense to talk about orthostatic hypotension.
4. Noise in the ears, ringing, perception of sound as through a thick film or glass.
5. Severe weakness, drowsiness, low tone.
6. Coldness, sometimes numbness of the extremities.
7. Pallor or even cyanosis of the skin, slow pulse (see normal pulse in a healthy person).
8. A feeling of lack of oxygen, while often a hypotonic person cannot take a full deep breath (“as if a hoop is squeezing the chest”).
9. Heartburn, belching of air.
10. Pain in the region of the heart, behind the sternum, shortness of breath.

With often low blood pressure, there may also be:

• tremor;
• irritability;
• tearfulness;
• impaired coordination of movements;
• staggering when walking;
• perception of the world "as in a dream";
• inability to concentrate;
• distraction of attention;
• low mental activity;
• constant yawning.

Danger of arterial hypotension

Low blood pressure does not pose a significant threat to health, especially in cases where it does not bring discomfort or is not a symptom of any disease or bleeding.

However, in some cases, significantly pronounced hypotension can affect the following:

1. due to slow blood circulation, "oxygen starvation" may occur;
2. at very low pressures, there is a risk of developing kidney failure and kidney failure;
3. frequent fainting can lead to injury;
4. the appearance of nausea and subsequent vomiting can provoke dehydration;
5. during pregnancy, low pressure poses a certain threat not only to the woman, but also to the fetus, in particular, due to insufficient oxygen supply;
6. there is some risk of stroke;
7. dangerously low blood pressure and the fact that cardiogenic shock is possible;
8. if, against the background of low blood pressure, there is a rapid pulse, tachycardia attacks, then this can become a significant threat to life and requires medical intervention.

How to increase low pressure yourself?

To bring the pressure back to normal, when it falls below the permissible limits, any "chemical" preparations are rarely used. Normalization is carried out with the help of herbal medicine, homeopathy, due to changes in the usual rhythm of life and in the diet. But there are also a number of emergency remedies that can quickly increase low blood pressure.

1. conduct a general body massage or lymphatic drainage;
2. sleep well, taking more than 8 hours to sleep;
3. after waking up, you should not abruptly get out of bed; it is better to lie down for a few minutes, making smooth movements with your arms and legs, doing a kind of exercise; only then slowly sit up in bed, stretch and then get up;
4. take regular walks in the fresh air, add more movement and activity to life; it is energetic activities that help raise low blood pressure without any problems; walking, light jogging, swimming in the pool or fitness center and other activities are recommended;
5. a contrast shower helps to get rid of malaise with hypotension;
6. avoid stuffy and hot rooms if possible; as well as sudden changes in temperature;
7. give up bad habits and an irregular daily routine, reduce mental stress as much as possible and do not forget to fully relax;
8. do not skip breakfast, and also eat fully throughout the day, supplying the body with enough fluid.

To quickly increase the pressure, you can resort to one of the following methods:

• do acupressure for a couple of minutes; massage should be done with soft, circular movements on the point above the upper lip and earlobes;
• drink a cup of freshly brewed strong black coffee with lemon slices or lemon juice added to the drink; coffee should be consumed in small sips, the drink should not be cold;
  instead of coffee, in order to quickly increase blood pressure and further normalize it, you can use strong green tea without additives; the drink is drunk only hot;
• if the pressure has fallen very low and sharply, physical activity will be impossible; then you should take a horizontal position, raising your legs and placing your head as low as possible so that there is an outflow of blood from the lower extremities; at this moment, you can inhale the vapors of mint essential oil;
• Citramon, which contains caffeine, or a caffeine tablet will also urgently increase blood pressure at home (read more about how Citramon increases blood pressure here).

Medicines that increase blood pressure

Despite the fact that medications are rarely used for hypotension, there are some drugs available in pharmacies that have a positive effect on the condition.

What pills increase blood pressure, except for citramone and caffeine?

1. Papazol.
2. Gutron.
3. Spazmalgon, Nosh-pa and other drugs that relieve spasms.
4. Nise, nurofen and other pain pills.
5. Camphor.
6. Mezaton.
7. Dobutamine.

Doctors also recommend some tinctures, often alcohol, to raise low blood pressure.

These include:

• tincture of ginseng;
• eleutherococcus;
• leuzei;
• Schisandra chinensis;
• pink radio.

Reception of tinctures should be carried out by people prone to low pressure, a couple of times a day 30 minutes before meals. The number of drops is calculated individually. A course of homeopathic tonics is especially required at times of weather changes, since with low blood pressure meteosensitivity is noted, in the autumn and spring seasons.

Products needed for hypotension

The most common options that are effective in helping to raise blood pressure at home are drinks and foods containing caffeine. In addition to green tea or coffee, it is useful to use cocoa, red Hibiscus tea, black bitter chocolate. In a hopeless situation, Pepsi or Coca-Cola will help raise the low pressure, but one should not get carried away with carbonated sweet drinks, as well as caffeine in general.

Do not forget about drinking plenty of water. A sufficient amount of fluid consumed per day thins the blood and increases its volume.

1. carrot;
2. sea ​​buckthorn, dried apricots;
3. cottage cheese;
4. buckwheat and rice cereals;
5. caviar and fish;
6. eggs;
7. lemons and black currants;
8. cherry;
9. sorrel;
10. butter;
11. potatoes, beans;
12. liver, red meat;
13. pomegranate and pomegranate juice;
14. horseradish, onion, garlic, salted nuts.

Folk remedies that increase blood pressure

The list of popular recommendations includes decoctions, tinctures and infusions, extracts of herbs, roots, plants, which have a beneficial effect on well-being at reduced pressure. It is also acceptable to use herbal preparations that combine individual components.

Top 10 Herbs to Fight Hypotension

1. St. John's wort.
2. Echinacea.
3. Immortelle.
4. Swamp calamus.
5. Thistle.
6. Yarrow.
7. Fireweed.
8. Blooming Sally.
9. Ginger.
10. Azalea roots.

In order not to be disturbed by sudden pressure drops, you need to be attentive and sensitive to your health. In situations of malaise, try to get rid of the root cause; if the correction of the condition does not bring results on its own, it is necessary to seek the advice of a doctor.

Question 1. How did J. B. Lamarck explain the diversity of species and the adaptability of organisms to specific environmental conditions?

J. B. Lamarck understood evolution as a process of progressive changes from one form to another, from simple to complex. According to his idea, all biological species (their diversity), including man, originated from other species.

Lamarck's theory was based on the inheritance of acquired properties that are useful for a given organism and are adaptations to specific environmental conditions. He believed that certain organs or organ systems in animals and plants are exercised and improved in the course of their life activity, and these improvements are fixed in the next generations.

Question 2. What are the main provisions of the teachings of Ch. Darwin?

Organisms are changeable. It is impossible to find two completely identical rabbits, wolves, lizards or other animals or plants belonging to the same species.
Differences between organisms are, at least in part, inherited.
Theoretically, under favorable conditions, any organisms can multiply so much that they are able to fill the Earth, but this does not happen, since many individuals die without having time to produce offspring.
Those organisms that have beneficial properties are more likely to survive than others. Survivors pass these properties on to their offspring. Consequently, these properties are fixed in a series of subsequent generations.

Question 3. On what facts did Darwin base the evidence for his theory?

The facts on which Darwin based his evidence for his theory are:

1) island plants and animals differ sharply from closely related species on the continent;

2) related species on different islands differ in appearance, body size, life habits against the background of diverse habitat conditions;

3) fossil remains of the giant sloth and armadillo were found, significantly larger than their relatives, still inhabiting Central and South America;

4) the preservation of marsupials and ovipositors precisely in Australia, where they found themselves isolated, and died out in other places on the globe;

5) differences between different breeds of the same kind of domesticated animals, which are sometimes even more significant than between different types of wild animals;

6) each organism is able to produce more offspring than it can survive, and only a limited number of them survive and leave their offspring.

Question 4. What facts allow us to talk about the struggle for existence? How does this struggle manifest itself in nature?

Living organisms tend to multiply exponentially and theoretically any organism can fill the Earth very quickly.

In fact, this never happens, because the resources of life are limited and go to only a few - those who can win the struggle for life, or the struggle for existence. material from the site

The intraspecific struggle for existence is manifested in different species, primarily in competition for food resources and a sexual partner. As a rule, a direct collision of individuals is prevented by various devices, among which marks should be distinguished that indicate an individual site: songbirds singing, leaving odorous secretions, etc. Violation of the boundaries of an individual site is often accompanied by fights. Less common is direct interaction, such as cannibalism.

Interspecific struggle is most clearly manifested in competitive relations between species occupying a similar life niche. A typical example is the relationship between black and gray rats. In addition, sometimes interspecific struggle refers to the relationship between predator and prey, parasite and host. Moreover, such interactions, as a rule, benefit both species, and the older the connection, the more effective mutual adaptation is and, as a result, conjugated evolutionary development occurs.

Question 1. Who created the first evolutionary theory?
The first truly scientific theory of evolution was formulated by the French naturalist Jean-Baptiste Lamarck (1744-1829) in 1809. In the Philosophy of Zoology, J. B. Lamarck proposed two positions of evolutionary doctrine. The evolutionary process is presented in the form of gradations, i.e. transitions from one stage of development to another. As a result, there is a gradual increase in the level of organization, more perfect forms arise, from less perfect ones. Thus, the first provision of Lamarck's theory is called the "rule of gradation".
The variety of forms arose as a result of the influence of the forces of the outside world, in response to which organisms develop adaptive features - adaptations. At the same time, the influence of the environment is direct and adequate. Organisms, being under the influence of the factors of the world around them, react in a certain way: by exercising or not exercising their organs. As a result, new combinations of traits and the traits themselves arise, which are transmitted in a number of generations (i.e., “inheritance of acquired traits” occurs). This second provision of Lamarck's theory is called the "rule of adequacy".

Question 2. What are the main provisions of the teachings of Charles Darwin?
Charles Robert Darwin (1809-1882) in his book The Origin of Species by Means of Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life (1859) formulated a new theory of evolution, the theory of natural selection. The main provisions of the theory of natural selection:
1. all organisms have the ability to change in the process of existence, they all have individual characteristics, so that there are no two identical creatures in nature;
2. personality traits, although not all, are transmitted from generation to generation, from ancestors to descendants (but not unconditionally and not all at once, as in the theory of J. B. Lamarck);
3. reproduction of organisms occurs according to the law of T. Malthus, i.e. exponentially, as a result of which organisms leave behind much more descendants than they survive before the start of future reproduction;
4. The death of most of the descendants occurs as a result of a fierce intra- and interspecific struggle for existence, as well as a struggle with natural elements, as a result, the fittest and strongest individuals survive and reproduce;
5. selective (selective) reproduction of the most adapted forms is called natural selection, which does not have the "gift of foresight";
6. as a result of the action of natural selection, new species, genera, etc. arise, and organisms gradually become more complex. Based on the above provisions of Darwin's theory, the following main driving forces of evolution can be distinguished: variability, heredity, the struggle for existence and natural selection.

Question 3. On what facts did Darwin base the evidence for his theory?
The facts on which Darwin based his evidence for his theory are:
1. island plants and animals differ sharply from closely related species on the continent;
2. closely related species on different islands differ in appearance, body size, and life habits against the background of diverse habitat conditions;
3. Fossil remains of the giant sloth and armadillo were found, significantly larger than their relatives, still inhabiting Central and South America;
4. the preservation of marsupials and oviparous in Australia, where they found themselves in isolation, and died out in other places on the globe;
5. differences between different breeds of the same species of domesticated animals, which are sometimes even more significant than between different species of wild animals;
6. Each organism is capable of producing more offspring than it can survive, and only a limited number of them survive and leave their offspring.