What is the light measured in, in what units? Units of measurement of physical quantities.

This lesson will not be new to beginners. We all heard things from school such as centimeter, meter, kilometer. And when it came to mass, they usually said grams, kilograms, tons.

Centimeters, meters and kilometers; grams, kilograms and tons have one common name - units of measurement of physical quantities.

In this lesson we will consider the most popular units of measurement, but we will not go deep into this topic, since units of measurement go into the field of physics. We are forced to study part of physics, because we need it to further study mathematics.

Lesson content

Length units

The following units are intended for measuring length:

• millimeters
• centimeters
• decimeters
• meters
• kilometers

millimeter(mm). Millimeters can even be seen with your own eyes, if you take the ruler that we used at school every day

A row of small lines following each other is millimeters. More precisely, the distance between these lines is equal to one millimeter (1 mm):

centimeter(cm). On the ruler, each centimeter is indicated by a number. For example, our line, which was in the first figure, had a length of 15 centimeters. The last centimeter on this line is highlighted by the number 15.

In one centimeter 10 millimeters. You can put an equal sign between one centimeter and ten millimeters, since they denote the same length

1 cm \u003d 10 mm

You can verify this yourself if you count the number of millimeters in the previous figure. You will find that the number of millimeters (the distance between the lines) is 10.

The next unit of length is decimeter  (dm). In one decimeter ten centimeters. Between one decimeter and ten centimeters you can put an equal sign, since they denote the same length:

1 dm \u003d 10 cm

You can verify this if you count the number of centimeters in the following figure:

You will find that the number of centimeters is 10.

The next unit is meter  (m). There are ten decimeters in one meter. You can put an equal sign between one meter and ten decimeters, because they denote the same length:

1 m \u003d 10 dm

Unfortunately, the meter cannot be illustrated in the figure, because it is rather large. If you want to see the meter live, take a tape measure. Everyone has it in the house. On a tape measure, one meter will be designated as 100 cm. This is because there are ten decimeters in one meter, and one hundred centimeters in ten decimeters:

1 m \u003d 10 dm \u003d 100 cm

100 is obtained by converting one meter to centimeters. This is a separate topic, which we will consider a little later. In the meantime, let's move on to the next unit of measurement of length, which is called kilometer.

A kilometer is considered the largest unit of length. Of course, there are other older units, such as a megameter, a gigameter terameter, but we will not consider them, since for a further study of mathematics we need only a kilometer.

One kilometer a thousand meters. Between one kilometer and a thousand meters you can put an equal sign, because they denote the same length:

1 km \u003d 1000 m

In kilometers, the distance between cities and countries is measured. For example, the distance from Moscow to St. Petersburg is about 714 kilometers.

SI international system of units

The SI international system of units is a set of generally accepted physical quantities.

The main purpose of the international system of SI units is to achieve agreements between countries.

We know that the languages \u200b\u200band traditions of the countries of the world are different. There is nothing to be done about it. But the laws of mathematics and physics work the same everywhere. If in one country “twice two will be four,” then in another country “twice two will be four.”

The main problem was that for each physical quantity there are several units of measure. For example, we have now learned that for measuring length there are millimeters, centimeters, decimeters, meters and kilometers. If several scientists speaking different languages \u200b\u200bgather in one place to solve a particular problem, then such a wide variety of units of measurement of length can create contradictions between these scientists.

One scientist will declare that in their country, length is measured in meters. The second may say that in their country, length is measured in kilometers. A third can offer his unit of measure.

Therefore, an international SI system of units was created. SI is an abbreviation for the French phrase Le Système International d’Unités, SI (which, translated into Russian, means the international system of SI units).

The SI shows the most popular physical quantities and for each of them has its own generally accepted unit of measurement. For example, in all countries, when solving problems, it was agreed that the length will be measured in meters. Therefore, when solving problems, if the length is given in another unit of measurement (for example, in kilometers), then it must be converted to meters. We will talk about how to transfer one unit of measurement to another a little later. In the meantime, we will draw our international SI system of units.

Our figure will be a table of physical quantities. We will include each studied physical quantity in our table and indicate the unit of measurement that is accepted in all countries. Now we have studied the units of measurement of length and learned that in the SI system, meters are defined for measuring length. So our table will look like this:

Mass units

Mass is a quantity that indicates the amount of substance in the body. People call body weight. Usually, when they weigh something, they say “It weighs that much kilogram” , although this is not about weight, but about the mass of this body.

However, mass and weight are different concepts. Weight is the force with which the body acts on a horizontal support. Weight is measured in Newtons. And mass is a quantity showing the amount of matter in this body.

But it’s okay if you call the weight of the body. Even in medicine they say "Person's weight" , although we are talking about the mass of man. The main thing to be aware that these are different concepts

The following units are used to measure mass:

• milligrams
• grams
• kilograms
• centners
• tons

The smallest unit of measure is milligram(mg). Milligrams most likely you will never put into practice. They are used by chemists and other scientists who work with small substances. It’s enough for you to know that such a unit of mass exists.

The next unit is gram(g). In grams, it is customary to measure the amount of a product in a recipe.

In one gram, a thousand milligrams. You can put an equal sign between one gram and a thousand milligrams, because they mean the same mass:

1 g \u003d 1000 mg

The next unit is kilogram(kg). A kilogram is a common unit of measurement. Everything is measured in it. A kilogram is included in the SI system. Let us also include one more physical quantity in our SI table. It will be called “mass” here:

In one kilogram, a thousand grams. You can put an equal sign between one kilogram and a thousand grams, because they mean the same mass:

1 kg \u003d 1000 g

The next unit is centner(c). In centners it is convenient to measure the mass of the crop collected from a small plot or the mass of some cargo.

One centner has one hundred kilograms. Between one centner and one hundred kilograms you can put an equal sign, because they denote the same mass:

1 kg \u003d 100 kg

The next unit is ton(t). In tons, large loads and masses of large bodies are usually measured. For example, the mass of a spaceship or car.

In one ton, one thousand kilograms. Between one ton and one thousand kilograms you can put an equal sign, because they denote the same mass:

1 t \u003d 1000 kg

Time units

What time we think is not necessary to explain. Everyone knows what time is and why it is needed. If we open the discussion to what time is and try to give it a definition, we will begin to delve into philosophy, and we don’t need it now. Better start with time units.

The following units are intended for measuring time:

• seconds
• minutes
• day

The smallest unit of measure is second  (from). Of course, there are smaller units such as milliseconds, microseconds, nanoseconds, but we will not consider them, because at the moment this makes no sense.

In seconds, various indicators are measured. For example, in how many seconds an athlete will run 100 meters. The second is included in the international SI system for measuring time and is denoted as “s”. Let us also include one more physical quantity in our SI table. We will call it “time”:

minute(m). In one minute, 60 seconds. Between one minute and sixty seconds you can put an equal sign, because they mean the same time:

1 m \u003d 60 s

The next unit is hour(h). In one hour 60 minutes. Between one hour and sixty minutes you can put an equal sign, since they mean the same time:

1 h \u003d 60 m

For example, if we studied this lesson for one hour and we are asked how much time we spent studying it, we can answer in two ways: “We learned the lesson one hour”   or so “We learned the lesson sixty minutes” . In both cases, we will answer correctly.

The next unit of time is day. 24 hours a day. Between one day and twenty four hours you can put an equal sign, because they mean the same time:

1 day \u003d 24 hours

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Unity of measurements implies consistency unit sizes  all sizes. This becomes apparent when one recalls the possibility of measuring the same quantity by direct and indirect measurements. This consistency is achieved by creating a system of units. But, although the advantages of a system of units in comparison with a set of disparate units were realized long ago, the first system of units appeared only at the end of the 18th century. It was the famous metric system (meter, kilogram, second), approved on March 26, 1791 by the Constituent Assembly of France. The first scientifically based system of units, as a set of arbitrary basic units and derived units dependent on them, in 1832 was proposed by K. Gauss. He built a system of units, called absolute, based on which were taken three arbitrary, independent from each other units: millimeter, milligram and second. The Gaussian system was developed in 1881 by the GHS system (centimeter, gram, second), convenient for use in electromagnetic measurements, and its various modifications.

The development of industry and trade in the era of the first industrial revolution required the unification of units on an international scale. The beginning of this process was laid on May 20, 1875 by the signing of 17 countries (including Russia, Germany, the USA, France, England) of the Metric Convention, which many countries subsequently joined. According to this convention, international cooperation in the field of metrology was established. In Sevres, located in the suburbs of Paris, the International Bureau of Weights and Measures (BIPM) was created with the aim of conducting international metrological research and storing international standards. To guide BIPM, the International Committee of Weights and Measures (CIPM) was established, including advisory committees on units and a number of types of measurements. To address the fundamental issues of international metrological cooperation, international conferences were regularly held, called the General Conferences on Weights and Measures (CGPM). All countries that signed the Metric Convention received prototypes of international standards of length (meter) and mass (kilogram). Periodic comparisons of these national standards with international standards stored in the BIPM were also organized. Thus, the metric system of units was first recognized internationally. However, after the signing of the Metric Convention, unit systems were developed for various measurement areas - GHS, GHSE, GHSM, MTS, ISS, ICSSS. Once again, the problem of the uniformity of measurements arises, already between different areas of measurement. And in 1954, the CGPMM tentatively, and in October 1960, the XI CGPMC finally adopted the International System of Units SI, which is currently in force with minor changes. At subsequent meetings of the CGPM, it was repeatedly amended and supplemented. Currently, the SI system of units is regulated by ISO 31 and is essentially an international regulation that is mandatory for use. In our country, the ISO 31 standard is approved as the state standard GOST 8.417-02.

SI system of units formed in accordance with the general principle of the formation of systems of units, which was proposed by K. Gauss in 1832. In accordance with it, all physical quantities are divided into two groups: quantities accepted as independent of other quantities, which are called basic quantities; all other quantities called derivatives, which are expressed through the basic and already determined derivatives using physical equations. The classification of units follows from this: units of basic quantities are the basic units of the system, and units of derived quantities are derived units.

So first formed system of quantities — a set of quantities formed in accordance with the principle when some quantities are taken as independent, while others are functions of independent quantities. A quantity that is part of a system of quantities conventionally accepted as independent of other quantities of this system is called the main quantity. The quantity included in the system of quantities and determined through the basic and already determined derivatives,called the derived quantity.

The unit of the basic quantity of this system of quantities is called the basic unit. Derivative Unit— it is a unit of a derived quantity of a given system of quantities formed in accordance with an equation linking it with the basic units or with the basic units and already defined derived units.

In this way system of units— set of basic and derived units of a given system of quantities.

Basic units of measurement.  For each measured physical quantity the corresponding unit of measure should be provided. So, a separate unit of measurement is needed for weight, distance, volume, speed, etc., and each such unit can be determined by choosing one or another standard. The system of units is much more convenient if only a few units are selected as the main ones, and the rest are determined through the main ones. So, if the unit of length is a meter, the standard of which is stored in the State Metrological Service, then the unit of area can be considered a square meter, the unit of volume is a cubic meter, the unit of speed is a meter per second, etc.

The convenience of such a system of units is that the mathematical relations between the basic and derived units of the system are simpler. In this case, the unit of speed is the unit of distance (length) per unit of time, the unit of acceleration is the unit of change of speed per unit of time, the unit of force is the unit of acceleration of a unit of mass, etc. In mathematical notation, it looks like this: v \u003d l / t, a \u003d v / t, F \u003d ma \u003d ml / t2. The presented formulas show the “dimension” of the quantities under consideration, establishing the relations between the units. (Similar formulas make it possible to determine units for such quantities as pressure or electric current.) Such ratios are general in nature and are fulfilled regardless of which units (meter, foot or arshin) measure length and which units are chosen for other quantities.

Radiation (or ionizing radiation) is a set of different types of physical fields and microparticles that have the ability to ionize substances.

Radiation is divided into several types and is measured using various scientific instruments specially designed for this purpose.

In addition, there are units of measure in excess of which can be fatal to humans.

The most accurate and reliable methods of measuring radiation

Using a dosimeter (radiometer), you can measure radiation intensity as accurately as possible, and examine a specific place or specific objects. Most often, instruments for measuring the level of radiation are used in places:

1. Close to areas of radiation (for example, near the Chernobyl nuclear power plant).
2. Planned construction of a residential type.
3. In unexplored, unexplored areas during hiking, traveling.
4. With a potential purchase of housing facilities.

Since purification from radiation of the territory and objects located on it is impossible (plants, furniture, equipment, structures), the only sure way to protect yourself is to check the level of danger in time and stay as far as possible from sources and infected areas. Therefore, under normal conditions, household dosimeters that successfully identify a hazard and its doses can be used to check the terrain, products, and household items.

Radiation regulation

The purpose of radiation monitoring is not just measuring its level, but also determining compliance of indicators with established standards. Criteria and standards for a safe level of radiation are prescribed in individual laws and generally established rules. The conditions for technogenic and radioactive substances are regulated for the following categories:

• Food
• Air
• Building materials
• Computer technology
• Medical equipment.

Manufacturers of many types of grocery or industrial goods are required by law to prescribe criteria and indicators of compliance with radiation safety in conditions and certification documents. The relevant public services are pretty strict in tracking various deviations or violations in this regard.

Radiation units

It has long been proven that the radiation background is present almost everywhere, just in most places its level is considered safe. The radiation level is measured in certain indicators, among which the main ones are doses - units of energy absorbed by a substance at the moment of passage of ionizing radiation through it.

The main types of doses and units of their measurement can be listed in such definitions:

1. Exposure dose  - created by gamma or x-ray radiation and shows the degree of ionization of the air; off-system units of measure - rem or "x-ray", in the international SI system is classified as "pendant per kg";
2. Absorbed dose  - the unit of measure is gray;
3. Effective dose  - determined individually for each body;
4. Dose equivalent  - depending on the type of radiation, it is calculated based on the coefficients.

Radiation can only be determined by instruments. Moreover, there are certain doses and established standards, among which the permissible indicators, negative doses to the human body and lethal doses are strictly specified.

Radiation Safety Levels

For the population, certain levels of safe values \u200b\u200bof the absorbed radiation doses are established, which are measured by the dosimeter.

Each territory has its own natural radiation background, but a value of approximately 0.5 microsievert (µSv) per hour (up to 50 micro-roentgen per hour) is considered safe for the population. Under normal radiation background, the most safe level of external exposure to the human body is considered to be up to 0.2 (µSv) microsievert per hour (a value of 20 micro-roentgens per hour).

Most upper limit permissible radiation level - 0.5 μSv - or 50 μR / h.

Accordingly, a person can transfer radiation, the power of which is 10 μZ / h (microsievert), and if the exposure time is reduced to a minimum, radiation of several millisieverts per hour is harmless. This is the effect of fluorography, x-ray - up to 3 mSv. A snapshot of a diseased tooth at the dentist is 0.2 mSv. The absorbed radiation dose has the ability to accumulate throughout life, but the amount should not cross the threshold of 100-700 mSv.

Light is simply necessary for every person for an excellent mood and mental health. Thanks to him, we get the opportunity to see objects, to distinguish between their shape and structure of materials, because the artificial prolongation of daylight hours can increase the efficiency and productivity. Choosing for yourself fixtures and lamps, do not forget that the light must be selected correctly. In rooms for various purposes, a variable approach to lighting intensity is permissible. And in order to choose the right fixtures, you need to know what the light is measured in.

  and artificial

All human health experts unanimously declare that the best for people is a natural light source. It contributes to the development of a number of vitamins and minerals in the body, and is also most favorable for the eyes. Each subject in natural light can be seen without distortion and glare.

But, unfortunately, the modern world dictates its own conditions, and we can no longer do without artificial light sources in the dark, otherwise the life of cities would completely stop. In each apartment there are a lot of different lamps, quite often we do not even imagine what the light is measured in and what you need to pay attention to in the store when buying a variety of sconces, floor lamps and lampshades.

What is the light like?

No less important than the selection of light intensity is the category or type of lighting. As we already said, the most pleasant and safe light is a natural source of lighting. It has a warm shade and is less harmful to the eyes. Closest to a similar tone were old incandescent lamps with a reddish tint of the light flux. They did not irritate the eyes and copied the sunlight falling into the windows of the apartments.

Modern lamps have many variations on the working element and the type of light. Before buying a new lamp, be sure to check what type of light is indicated on the package. For example, warm light will be ideal for living quarters. And neutral is usually used in offices and huge production facilities. Cold light is often used in watchmaking workshops, where its bluish tint helps to distinguish small details. Cold shades of light in subtropical countries are also welcome, where they create a feeling of additional coolness and transparency of the air.

Based on the above, you can always choose the right type of light bulb, which will create the necessary mood and level of comfort for you in a relaxing home atmosphere. Psychologists have proved that the type of light plays a serious role in shaping the working mood in enterprises. Naturally, labor productivity also depends on this.

What parameters measure the light intensity?

The average buyer does not even think about how light is measured and how important this information is. After all, light, being measured in many quantitative and qualitative parameters. They must be taken into account when planning repairs in an apartment and counting the number of bulbs needed for each room.

Light can be measured by the following characteristics:

• intensity
• power;
• brightness.

Just like that, “by eye” you will not be able to determine all the necessary parameters, so you should take care of buying devices that will help you maintain your vision and a positive psychological attitude at any time of the day.

What is the brightness of light measured in?

Brightness is a very important characteristic of a light source. It is the brightness of lighting that allows us to see all the objects around us clearly and in contrast. Thanks to brightness, spatial perception and exposure of white and black shades are aggravated. In addition, it is the brightness of the light source that determines the degree of comfort when reading a printed text, and this, as you know, directly affects the health of the eyes.

If we are talking about brightness, then it is very easy to remember in which units light is measured. Most often, candela is used to measure the brightness of a light source. This unit indicates the burning brightness of one candle, it is from it that all measuring devices repel. Sometimes experts also use other units of measurement - lambert and apostille.

What instrument can measure the brightness of lighting?

Modern specialized equipment stores are always ready to provide customers with a large number of various instruments for measuring light brightness. Brighteners and colorimeters do the job best. They are able to give you information not only on the degree of brightness in a particular room, but also determine the color temperature of the room.

Advanced function devices are suitable for professional studio photographers. And for household needs, a conventional brightness meter, which does not have additional options, is suitable.

In what

Luminous intensity - According to the school course of physics, it can be described as the energy of light, which can be transferred from one point to another over a certain period of time. This energy can change direction depending on the given trajectory.

The energy of light in candelas is measured. That is, having bought a brightness meter for home use, you can always measure not only brightness, but also light intensity.

Light intensity: what is measured?

The light intensity is often called illumination, and it is also important when choosing fixtures and various types of lamps. Even a child can remember how light intensity is measured, although some nuances should be taken into account here.

If we are talking about falling onto a certain surface, then it is necessary to measure in lumens. But if you want to find out the degree of illumination of objects or surfaces, you need to talk about suites.

Such subtleties often scare buyers who have heard somewhere that the light is measured in lumens and are perplexed by the incomprehensible units of measurement indicated on the package from the light bulb. To cope with the problem of determining the degree of illumination in the room will help a very common device - a luxometer.

Luxometer - a device that maintains healthy vision

If you can hardly remember in which units the light is measured, then the luxometer will save your time and nerve cells. This device has a small size and weight, most often it consists of a display and a measuring part.

You can use such an assistant at home, in educational institutions or office premises. To obtain data, you just need to turn on the light source, and take measurements. In just a few seconds, you will see the result on the display, which will show how safe your eyes are for your bulbs and lamps.

  for apartments and other residential premises

In order to choose lighting that is comfortable for the eyes, it is not enough to know what the light is measured in. You also need to have information about the lighting standards, which you should be guided by when planning the location of lighting devices in the apartment.

Each room and room has its own necessary degree of illumination, which is measured in suites. For example, the nursery should be the most lighted room in the apartment. There can not be less than two hundred suites, otherwise the baby's health will be in great jeopardy.

The kitchen and other rooms can be illuminated for one hundred and fifty suites, but the utility rooms and corridors are quite costing fifty suites. Compliance with these standards guarantees your family a comfortable existence, excellent mood and vision, which even an eagle will envy.

If you care about your family, you should know exactly what bulbs are installed in the lamps of your apartment. After all, every sane person dreams of returning from work to the house, where cheerful children and a caring wife in a good mood are waiting for him. And an important role in making the dream finally become a reality is played by well-chosen lighting.

Add up to two numbers. The upper one is called the systolic value, and the lower one is called the diastolic value. Each of them is consistent with a specific norm, depending on the age category of the person. Like any physical phenomenon, the strength of the blood flow that presses on the muscle layer of the vessels can be measured. These indicators are fixed by means of a scale with divisions on the manometer. Marks on the dial are correlated with a certain measure of calculation. What units are used to measure blood pressure? To answer this question, we must turn to the history of the first tonometers.

Pressure is a physical quantity. It must be understood as a certain force that acts on a certain section of a certain area at right angles. This value is calculated according to the International System of Units in Pascals. One pascal is the effect of a perpendicular directed force of one newton per square meter of surface. However, when using a tonometer, other units are used. What is the blood in the vessels?

The readings on the scale of the mechanical pressure gauge are limited by digital values \u200b\u200bfrom 20 to 300. There are 10 divisions between adjacent numbers. Each of them corresponds to 2 mm RT. Art. Millimeters of mercury - these are the units for. Why is such a measure used?

The first sphygmomanometer ("sphygmo" means "pulse") was mercury. He examined the force of blood pressing on blood vessels using a mercury column. The substance was placed inside a vertical flask graduated with millimeter serifs. Under the pressure of the air flow pumped by a rubber bulb into a hollow inelastic cuff, mercury rose to a certain level. Then the air gradually blew off, and the column in the flask descended. His position was recorded twice: when the first tones were heard, and when the last pulsations disappeared.

Modern blood pressure monitors have long been working without the use of a dangerous substance, but blood pressure is traditionally measured, in millimeters of mercury, to this day.

What do the numbers indicated by the tonometer mean?

The blood pressure value is represented by two digits. How to decrypt them? The first or upper indicator is called systolic. The second (lower) - diastolic.

Systolic pressure is always higher, it indicates the force with which the heart ejects blood from its chambers into the arteries. It occurs at the time of myocardial contraction and is responsible for the delivery of oxygen and nutrients to organs.

The diastolic value is equal to the resistance force of the peripheral capillaries. It is formed when the heart is in the most relaxed state. The force of the vascular walls, acting on red blood cells, gives them the opportunity to return to the heart muscle. The capillary force that presses on the blood stream, which occurs during diastole (resting the heart), largely depends on the functioning of the urinary system. Therefore, this effect is often called renal.

When measuring blood pressure, both parameters are very important, together they provide normal blood circulation in the body. So that this process is not disturbed, the tonometer values \u200b\u200bshould always be within acceptable limits. For systolic (heart) pressure, an indicator of 120 mm Hg is considered the generally accepted norm. Art., and for diastolic (renal) - 70 mm RT. Art. Minor deviations in one direction or another are not recognized as pathology.

Normal Pressure Limits:

1. Slightly underestimated: 100 / 65-119 / 69.
2. Standard rate: 120 / 70-129 / 84.
3. Slightly overpriced: 130 / 85-139 / 89.

If the tonometer gives an even lower value (than in paragraph one), this indicates hypotension. With persistent elevated numbers (above 140/90), the diagnosis of hypertension is made.

Based on the identified pressure parameters, the disease can belong to one of three degrees:

1. 140 / 90-159 / 99 are 1st degree values.
2. 160 / 100-179 / 109 - indications of the 2nd degree.
3. Everything above 180/110 is already the 3rd degree of the disease.

The easiest of them is the first degree. With timely treatment and compliance with all the recommendations of a doctor, she is cured. The third poses the greatest danger; it requires constant use of special pills and threatens a person’s life.

Blood Pressure: Age Dependent

Standard numbers are averaged. They are not so common in the generally accepted form. The values \u200b\u200bof the tonometer of a healthy person are constantly fluctuating, because the conditions of his life, physical well-being and mental state are changing. But these fluctuations are not essential for the full functioning of the body.

Indicators of pressure in the arteries also depend on what age category the man or woman belongs to. Starting from the neonatal period and ending with a very old age, the hands of the measuring device tend to show ever higher numbers.

Table: systolic and diastolic pressure norms corresponding to a specific age and gender.

Number of years	0-1	1-10	11-20	21-30	31-40	41-50	51-60	61-70	71-80	81-90
Systolic   indicators,   women	95	103	116	120	127	137	144	159	157	150
Diastolic   indicators,   women	65	70	72	75	80	84	85	85	83	79
Systolic   options,   male gender	96	103	123	126	129	135	142	145	147	145
Diastolic    indicators,   male gender	66	69	76	79	81	83	85	82	72	78

As can be seen from the table, gender also matters. It was noted that women under 40 years of age have lower blood pressure than men. After this age, the opposite phenomenon is observed. This difference is due to the action of specific hormones that maintain a good condition of the circulatory system of the fair sex in the childbearing period. With the onset of menopause, the hormonal background changes, the protection of blood vessels weakens.

The parameters of the measured pressure in the elderly also differ from the generally accepted norm. They are usually higher. But at the same time, people feel good with these indicators. The human body is a self-regulating system, and therefore a forced decrease in habitual values \u200b\u200bcan often lead to poor health. Vessels in old age are often affected by atherosclerosis, and in order to fully supply the organs with blood, the pressure should be increased.

Often you can hear such a combination as "working pressure". This is not a synonym for norm, simply due to physiological characteristics, age, gender and state of health, each person needs “his” indicators. With them, the vital activity of the body proceeds under optimal conditions, and a woman or a man feels alert and active. The ideal option when the "working pressure" matches the generally accepted standards or not much different from them.

To determine the optimal indicators of the tonometer, depending on age characteristics and weight, you can use special calculations called the Volynsky formula:

• 109+ (0.5 * number of years) + (0.1 * weight, taken in kg) - systolic value;
• 63+ (0.1 * years lived) + (0.15 * weight in kg) - diastolic parameters.

Such calculations are advisable for people from 17 to 79 years old.

People tried to try to measure pressure since ancient times. In 1773, Stefan Hales, an Englishman, attempted to study the pulsation of blood in a horse’s artery. A glass test tube was connected through a metal tube directly to a vessel clamped with a rope. When the clamp was removed, the blood falling into the flask reflected pulse fluctuations. She moved up and down. So the scientist was able to measure blood pressure in different animals. For this, peripheral veins and arteries, including pulmonary, were used.

In 1928, the French scientist Jean-Louis Marie Poiseuille was the first to use a device showing the level of pressure with a mercury column. The measurement was still taking a direct path. Experiments were performed on animals.

Carl von Feerordt invented the sphygmumgraph in 1855. This apparatus did not require direct introduction into the vessel. With its help, the force was measured, which had to be applied to completely stop the movement of blood through the radial artery.

In 1856, the surgeon Favre, for the first time in the history of medicine, performed a blood pressure measurement in humans in an invasive way. He also used a mercury device.

The Italian doctor S. Riva-Rocci in 1896 invented a pressure meter, which became the progenitor of modern mechanical blood pressure monitors. It included a bicycle tire to tighten the upper arm. The tire was attached to a manometer using mercury to record the results. A kind of cuff also communicated with a pear made of rubber, which was supposed to fill the tire with air. When the pulse in the hand ceased to be felt, systolic pressure was recorded. After the resumption of pulsating shocks, a diastolic indicator was noted.

1905 is a significant date in the history of tonometers. N. S. Korotkov, military doctor, improved the principle of operation of the Riva-Rocci sphygmomanometer. He belongs to the discovery of an auscultatory method for measuring blood pressure. Its essence was to listen to a special device for noise effects arising inside the artery just below the cuff compressing the shoulder. The appearance of the first knocks during air bleeding indicated systolic significance, the silence that arose signified diastolic pressure.

The discovery of the existence of blood pressure in humans, as well as the discoveries of scientists in the field of its measurement, have significantly advanced the development of medicine. The values \u200b\u200bof systolic and diastolic indicators will help an experienced doctor understand a lot about the patient’s health status. That is why the first tonometers contributed to the improvement of diagnostic methods, which inevitably increased the effectiveness of therapeutic measures.

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