Circulatory system

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Content

Introduction

1. Review of the literature

1.1 Age-related changes in blood pressure of

1.2 Age changes in heart rate

1.3 The influence of school stress on the cardiovascular system of student

2. Results of the study

2.1 Goals and objectives

2.2 SUBJECTS AND METHODS

2.3 Results and discussion

2.3.1 Blood pressure of students in a state of relative calm

2.3.2 The change of parameters of the cardiovascular system in children under the influence of one class of workload

2.3.3 The change of parameters of the cardiovascular system in grade 3 students

2.3.4 Blood pressure and heart rate in grade 5 students

2.3.5 Determination of vegetation index in students

2.3.6 Comparative characteristics of blood pressure and heart rate of students 1, 3 and 5 classes

Conclusions

Introduction

The subject of modern physiology is the study of the specific functions of cells, organs and systems of coordination of these functions in the whole organism, which provides a perfect adaptation of man to the surrounding environment. It is from this angle that Claude Bernard once defined the adaptation - adaptation - as the final issue of physiology. In recent times this fundamental problem has significant practical importance.

Physiological research is closely related to the problems of adaptation in extreme conditions, and under the influence of factors affecting in usual activities.

Of particular interest and practical importance of the issue of adaptation in the physiological reserves in developing, growing child [1, 2].

Due to the fact that the child is in the wild, especially in the learning process has to deal with a wide range of mental and muscular loads used to develop his specific qualities and skills, experts in the field of Developmental Physiology, medical control, the practice of physical education and labor training important to know how the child's body adapts to different loads, what are the functional changes at the same time, their optimal boundaries and opportunities at different stages of ontogeny.

One of the pressing issues of Physiology-setting is critical and crucial period of development [3].

While training and exercise, as well as the environment in which learning takes place in school, far from the extremes, there is every reason to believe that students' adaptation process takes place at all levels of functioning of the body - from the sub-cellular - molecular to holistic.

Urgent task of Physiology is the study of the functionality of the cardiovascular system in children of all ages in learning activities. Changes in the functional state of the cardiovascular system of the child in the school are made up of age and adaptation. Study age-cardiovascular system of the body of the child and its functionality at different stages of ontogeny by the need to develop theoretically sound methods of health care, education and training, based on the knowledge of the laws of the child's physiological development.

Importance of the study of adaptation of the cardiovascular system to the course of action is determined by the fact that schooling is a relatively long-acting factor that has an impact on the personal development of children and adolescents [4].

Despite the large number of studies on the cardiovascular system, to date there is no clear objective characteristics of structural and metabolic changes that occur in the system at each age period. Remains poorly known structure of the cardiovascular system in children of preschool and school age.

Among specialists in Physiology no single me-tion about the impact of learning activities on the basic parameters of the circulatory system. Meanwhile, vascular dysfunction is not uncommon in children and adolescents, as these age periods of the cardiovascular system is particularly sensitive to the impact of unfavorable factors and needs rational mode of mental and physical activity. [5]

1. LITERATURE REVIEW

1.1 Age-related changes in blood pressure

The cardiovascular system, in essence, provides physical and mental abilities of man and its limits in violation of functional status. [6]

Marked lability of the cardiovascular system is the cause of the adequacy of the study of its key indicators as criteria for adaptation to any type of activity and changes in the body in response to a variety of exposure. [7]

The cardiovascular system is the main part through which the central nervous system is in its "administrative and distribution" function, and a universal indicator of the human condition. [8]

The circulatory system in its structure is closed, hence the functional relationship between its elements. Is divided into three main sections in the cardiovascular system: the central hemodynamics, peripheral circulation and microcirculation. On this division is quite clear, as in the response of the body are affected more often than all the links, but the degree of involvement of various departments of the circulatory system in the implementation of adaptive effect is different.

The main indicator of central hemodynamics in determining the state of the circulatory system is the blood pressure, which is determined by cardiac output and systemic vascular resistance. In a healthy body establish certain relationships between them, aimed primarily at maintaining blood pressure - the parameter determining the effectiveness of tissue blood flow. In the process of growth and development of human central hemodynamics change, and at puberty the deviations from the optimal relationships between them. [4]

Essential to characterize the functional state of the circulation, an assessment of blood pressure and heart rate that derive a complex set of regulatory and hemodynamic effects: the state of the heart, blood vessels and tissues. [9]

Studies of blood pressure in children and young adults began in the early decades of this century, it was found that the blood pressure in children significantly increases with age [10, 11].

To date, accumulated a great amount of material changes in blood pressure in different age periods.

Perceptions of age-related changes in blood pressure in different researchers are rather contradictory. Some authors believe that from birth to 7 - 9 years old, it does not change and only then is it increasing, while others believe that from birth to 13 - 15 years, there is a continuous increase in blood pressure. Has now been shown that both systolic and diastolic blood pressure naturally increases with age, in parallel with the increase of the longitudinal dimensions and weight [4, 12, 13].

In the human brachial artery systolic pressure is 110 - 125 mm Hg and diastolic - 60 - 85 mmHg

In children, blood pressure is much lower than in adults. The younger the child, the more he has more capillary network and wider clearance shelter-bearing vessels, and, consequently, lower the blood pressure [14, 15].

Quite substantially increases blood pressure in the first year of life. A child of 1 year systolic pressure of 85 mmHg [16, 17].

According to some authors on blood pressure is influenced by many factors: gender, age, physical development, atmospheric pressure, as well as climatic and geographical characteristics of the various regions of the country [9, 18, 19].

Thus, almost all the blood pressure in children 3 - 7 years, Alma-Ata were significantly lower standards for children in Moscow. [20]

Changes in the level of blood pressure over a period of 1.5 to 6 years is characterized by the initial decline and its subsequent increase after four years, with the most intensive growth in girls and boys 5 years to 6 years [21]. Systolic blood pressure in children aged 2 to 6 years is increased gradually from 94.7 to 98.5 mm Hg, minimum from 55.4 to 57 mm Hg [22]. These data are somewhat higher than those I.N.Vulfson F.M.Kitikar and [23].

According to other researchers in the 5, 6 and 7 years old, the mean diastolic blood pressure of 48 - 66, 51 - 70 and 53 - 71 mmHg respectively [24, 25, 26].

The cardiovascular system of the child is very different from the cardiovascular system of an adult man. This difference is especially noticeable in the functional state of the circulatory system. [27]

Blood pressure in children is much lower than in adults: systolic pressure-parameter in 6-year-old child is not normally exceed 95 - 105 mmHg This is for two reasons:

first - body size of children is much less, therefore, the mass of the column of blood pressure which must be overcome by the heart, about 2 times lower;

second - peripheral resistance to blood flow in children is much lower due to the specific features of vasomotor reactions vascular tone in children more permanent and can not be regulated as effectively as adults. [22]

Up to 5 years old blood pressure in boys and girls about the same, at this age does not reveal reliable sex differences in hemodynamic parameters [20, 24].

Population of healthy children, even in a uniform age-sex group in hemodynamic respect is heterogeneous. spread hemodynamic - Impact (SV) and minute (MO) volume of blood, total peripheral vascular resistance (SVR) - the children revealed from the newborn period, most clearly represented in adolescence. With age, there is an increase of Defense and OPSS. At the age of 6 - 8 years, these figures are higher in boys than in girls. [25]

A marked increase in blood pressure observed in the age of 5 - 7 years, which is probably due to the shift of the first growth and indicates the presence of functional reorganization of the cardiovascular system of the child during this period [20, 21, 29].

In general, the pre-school age is an intense period in the development of the cardiovascular system [24].

RA Kalyuzhnaya claims that the blood pressure of today's children and young people in an average of 10 - 20 mmHg higher than that of their counterparts 30 and 10 years ago. It is now evident that the upper limit of normal blood pressure for primary school children is the level of 110/60 mm Hg, and for 8 - 10 classes - 130 mmHg for systolic and 70 - 75 mmHg for diastolic blood pressure. Mental and emotional overload today's students, combined with a sedentary lifestyle contribute to the transition of physiological temporary rise in blood pressure in a more stable dysregulation of vascular tone [6].

The comprehensive study of contractile function infarction, central hemodynamics and peripheral circulation have established stages of development of the cardiovascular system in children and adolescents in the process of training and education in the school.

The first phase was observed in children aged 8 - 9 years and is characterized by a significant increase of central hemodynamics. The second phase is characteristic for children between the ages of 11 - 12 and 14 - 15 years. At this time, a relative stabilization of the growth parameters of central hemodynamics. The third stage is revealed in students 14 - 15 years old, going to 17, and is characterized by a tendency to reach a definitive level of central hemodynamics. [4]

Analysis of the major age-related changes of hemodynamic parameters shows that they are all more or less change over time in school [4, 30].

Annual basis, the study of all types of blood pressure in different age-sex groups of schoolchildren possible to establish different degrees of increase in the maximum and average pressure in boys and girls [31, 32].

The average annual increase in systolic blood pressure of the moment of birth until the age of 20 is about 2.0 mm Hg for boys and 1.0 mmHg for girls. Increase in diastolic pressure is less pronounced than the increase in systolic pressure and no significant differences between boys and girls, apparently not. The average annual increase in diastolic blood pressure in children and adolescents 0.5 - 1.0 mmHg for both boys and girls. [10]

With age, the average systolic blood pressure increased from 88.7 mmHg a 7-year-old boys to 118.0 mmHg the 16-year-olds, girls, respectively, with 85.4 to 112.7 mmHg [33, 34].

In most of the studied age groups revealed no statistically significant differences in systolic blood pressure in both boys and girls. However, if at a young age (7 - 9 years), systolic blood pressure as the average values, and on the cut-off point is almost the same for boys and girls, from 10 to 14 years, it is higher in girls, and 15 - 17 years is much higher in boys. The young men of 10 and 15 years, systolic blood pressure was significantly higher than that of girls. [33]

Minimum blood pressure, boys and girls also increases with age (from 54.1 to 71.3 mm Hg for boys and from 52.1 to 72 mm Hg for girls). Pulse pressure also increases with age (from 31.15 mm Hg at 7 years to 43.3 mm Hg at 17 years in boys and from 31.1 to 38.4 mm Hg for girls) [33, 34, 35].

Many researchers under physiological norm understand the range within which ensures optimal life and functioning, thus recognizing the dynamism of the norm [22].

It is now established that the dynamics of physiological and bio-logical constants in adolescents is correlated with the degree of physical and sexual development, as well as the size and volume of the heart and body weight [6, 36, 37, 38].

Most studies have found an association between blood pressure, height and weight [10, 39].

Revealed a clear dependence fluctuations in systolic and minute volume of the degree of physical development. The highest rates were recorded in the high teens growth. And maximum lateral pressure was higher in adolescents with severe degree of acceleration, with higher numbers in boys [38].

Data obtained K.N.Irzhanskoy, K.M.Hodak suggest that each group identified adolescents with abnormal blood pressure of regulations related to the different configuration of the heart. Adolescents with hypertrophic heart most often found increased, and among adolescents with low heart, on the contrary, low blood pressure [33, 36].

In I.O.Tupitsyna [4] the change of all kinds of arterial pressure in students 7 - 16 years (Table 1). Minimum blood pressure in boys with age gradually increases, with the most intensive process takes place from 11 - 12 years to 16 years, when it increased by 5 - 6 mm Hg Minimum blood pressure gradually increases and schoolgirls, but if up to 10 - 11 years it has been somewhat higher or not different from that of the boys, to 16 years to bear on the lower level (Table 2). [4]

The mean diastolic blood pressure at age 7 - 9 years higher in boys, and from 10 to 14 years as well as systolic and higher in girls [28, 29].

Mean blood pressure in boys increased from 7 to 9 years, and in the age of ten, was significantly reduced and did not differ from its value at 7. Further growth and development of the students were accompanied by fairly gradual increase of average pressure, and from 12 to 16 years, it grew by 6.6 mmHg In girls, a significant increase in mean arterial blood pressure decreased to 11, 12 to 16 years of absolute values were lower than those of students of the same age. [4]

More pronounced in boys age dynamics traced in maximum blood pressure. Reveal its authentic rise of 7 to 9 years and the subsequent drop in 10 years. Starting from 11 - 12 years there was a gradual steady increase in the maximum pressure [4, 40].

Increasing the maximum arterial pressure is uneven. The greatest increase in its different for boys in the 10 - 11 and 15 - 16 years old girls - 8 - 9 and 11 - 12 years [33, 34]. At 16 girls obtained maximal blood pressure is lower than that of boys in this age group. [4]

Pulse pressure also increases with age (from 31.15 mm Hg at 7 years to 43.4 mm Hg at 17 years in boys and from 31.1 to 38.4 mm Hg for girls) . Significant differences between the values ??of pulse pressure in both boys and girls were observed, except for 13, 14 and 17 when the pulse pressure is much higher in males [33, 34].

Complex pattern of age-related changes in blood pressure and cardiac output combined with fluctuations in the proportion of peripheral resistance, which had a tendency to increase to 16 years.

Thus, the age dynamics of the main parameters determining the state of central hemodynamics among females was slightly different from that of the students.

Age 9 to 10 years should be seen as a watershed in the development of the cardiovascular system, because in this period the focus of age-related changes of blood pressure in boys and girls is the opposite. With the end of puberty in girls (14 - 15 years) and boys (15 - 16 years) hemodynamic values ??are set at the level characteristic for adults. There is no doubt that puberty is associated with significant changes in the functioning of the circulatory system. [4]

1.2 Age changes in heart rate

Based on the concept of the cardiovascular system as an indicator of adaptive activity of the whole organism, we must first turn to the analysis of heart rate - the universal reaction of the body in response to any load [24, 38].

According to modern concepts, the heart rate is an informative indicator and its study may provide valuable information on the state of the regulatory systems of the body [42].

Indicators of heart rate, and blood pressure as well as in a state of relative calm with the age change. [30] The heart rate is usually measured by pulse as each release of blood vessels leads to a change in blood flow, vascular wall tension that is felt in the form of shock [13].

Well known fact that in the age of Cardiology is the steady pulse slowing with age, as a result of changes in the lability of the sinus node and the emergence of more sophisticated forms of neurohumoral regulation of the heart and above all strengthening tonic influence of the vagus nerve [43, 44].

In the first years of life pulse is not stable, not always rhythmic and to what - the extent such are up to 6 - 7 years. Starting from 7 - 8 years pulse becomes rhythmic, steady, right. This feature of the heart due to the fact that in this age mostly completed development of the nervous regulating mechanism heart rate [28]. The boys and girls in a state of rest at the age of 7-12 years pulse no sign of slowing of. Moreover, the girls aged 10 -11 years pulse rate. And with only 13 years of age begins the process of progressive shortening of the pulse [45].

In normal adult heart rate -75 beats in 1 minute. In infants is much higher - 140 beats per minute. Intensively decreasing during the first years of life, a heart rate of 90-85 years to 8-10 beats per minute, and to 15 years is close to adult size. [13]

Mean values of heart rate tends to a slowing of-age boys and range from 92 beats per minute at age 7 to 75 beats per minute in 17 years in girls, respectively, C92 to 79 beats per minute. In all age groups the heart rate in girls than in boys. [34] E.A.Aksyanova, M.A.Syrtsova in 5, 6 and 7 years of age, respectively, heart rate was recorded within 86-108, 84-100 and 80-100 per minute [24].

According D.A.Farber heart rate in children aged 7 years 91.2 beats / min, 10 years old - 78.7 beats / min [22, 28].

In children, the heart rate is higher than in adults, which is caused by the higher prevalence of metabolic and tone of the sympathetic nerves. Most heart rate in children is essential for cardiac output, ie the amount of blood ejected by the heart in one minute. Shock, or systolic blood volume in children is small, and providing the necessary blood flow to organs and tissues is achieved quickening activity of the heart. [28] Growth and development of children is accompanied by adequate reforms systemic hemodynamics, which is characterized by a natural increase in cardiac output due to preferential growth in stroke volume and cardiac output speed [21, 46].

The amount of blood ejected by the heart into the aorta at one newborn reduction of 2.5 cm 3 (Table 3). For the first year, it increased by 4 times, to 7 years - 9 times, and the 12 - to 16.4-fold [13].

1.3 The influence of school stress on the cardiovascular system students

In school, as an important factor in the lives of children, places considerable demands on the body of the child. The total course load consists of several components. Chief among them is the mental stresses to which children are exposed to the whole learning process. In addition, the school of life plays an important role component static load due to the school giponineziey. It is known that mental work significantly changes the state of the circulatory system. [4]

Currently, there is an extensive literature on the reactions of selected indicators of blood circulation in response to mental stress. Based on the analysis identified two points of view. One group of researchers believe that learning activity causes increased heart rate, rise in blood pressure, increased stroke volume. Others, on the contrary. - Slowing of the heart rate, drop in blood pressure and a decrease in stroke volume [47].

Studying in school children 7 - 17 years old simple methods change arterial pressure (as Korotkov) and heart rate (palkatorno) T.N.Serdyukovskaya found that by the end of school term, semester and year, a decrease of maximum blood pressure in all age groups. Despite the fact that the number of examinees was great, clear dynamics of the minimum pressure and heart rate could not be detected [4, 48].

S.B.Dogadkinoy I.O.Tunitsynym and [49] was used to study the change-tions central hemodynamics preparatory school - IV class from the beginning to the end of the school year.

Children kindergarten to the end of the first half was found significantly reduced the minimum, average and lateral pressure, as well as the specific peripheral resistance. Throughout the school year, the maximum amount of blood pressure, stroke and minute volumes remained relatively constant. By the end of the school year for children 6 years of age there were favorable changes in the functioning of the cardiovascular system.

It was found that the students of class I from the beginning to the end of the school year, a decrease of all types of blood pressure, reduction in heart rate, a significant increase in cardiac output, lower resistivity. These changes indicate a particularly pronounced in this category of children, "school stress" [6, 50, 51].

Fluctuations in heart rate in first grade at the lesson of the Russian language, mathematics, reading, no more than 10 strikes in the first 13-17 minutes of academic work. Then the stability of broken heart. [52]

The students grade 3 were observed small shifts the maximum arterial pressure and heart rate slow down. Cardiac output and peripheral resistance increased specific [4].

In older children (9 - 10 years), all shifts circulation less pronounced than in younger (7 - 8 years), indicating a perfect vanii-adaptive mechanisms of age-related and better adapt to the training load [6]. According to the results obtained by other authors, the maximum blood pressure at rest in children 1 and 3 classes to the end of the school year has not changed, and by the end of the first half was the boys Class 1 101 mm Hg girls - 96 mm Hg, while the pulse pressure in boys decreased by 3 mmHg [53].

The transition to teaching in grade 4 caused several other changes of central hemodynamics during the school year. Maximum arterial pressure decreased, heart rate decreased, but, in contrast to the younger students, the fourth-graders there was a decrease in cardiac output [4].

In boys Class 4 by the end of the school year there was a significant reduction in the maximum arterial pressure and cardiac output, whereas the age trend in the development of cardio - vascular system is to increase these figures.

Raising the minimum while reducing the maximum blood pressure is regarded as an adverse reaction of the cardiovascular system workload [48, 52].

Thus, under the influence of the learning activities is complex of changes in blood flow. The most intense adaptation of the cardiovascular system to the learning activities of students observed in one class, and the boys four classes [49].

Monitoring of blood pressure and pulse rate in schoolchildren 3, 5, 8 classes conducted over 2 years, have shown that heart rate is influenced by students' school load increased by 10-15 beats per minute. In addition, heart rate changes during the day. So he came to the school, the student is slow pulse (85-90 strokes), after the first few lessons pulse quickens (95 strokes), and by the end of the day there is an even greater increase in pulse rate: 90-100 beats per minute. Before the test operation is increased heart rate of 10-15 beats per minute. [54] From the literature it is well known that a prelaunch and predrabochem state is quickening the pulse rate. Predrabochie modification of physiological function can be seen as the emergence of the working of the dominant [9]. To a normal rhythm of morning heart rate is approaching only after a long rest.

It has been observed that by the end of the week and a quarter of the pulse remains a trend towards an increase in the frequency. While there is a morning and increased heart rate by 2-5 beats per minute.

Blood pressure in school children 3, 5, and 8 of 93-117 mmHg at 60-78. Under the influence of the teaching load, it changes a little and has a tendency to fall. Increased blood pressure after the tests, and after the emotional stress from 105-66 to 112-70 mmHg

At the end of the day the blood pressure in school children did not increase, but several reduced and restored only in the morning before lessons. [54]

Analyzing the data obtained during the examination of students of 9th grade 10, the authors noted that in the beginning of the year in boys 9th grade systolic blood pressure did not differ from the systolic blood pressure in women, diastolic blood pressure below the girls at the beginning and at the end school year. In 10 classes throughout the school year, systolic and diastolic blood pressure in boys above.

All surveyed tended to reduce these indicators by the end of the first half and returned to baseline levels by the end of the school year.

It should be noted that the cardiovascular system of the girls is more pronounced under the influence of the sympathetic nervous system. It can be concluded from the analysis of the average values ??of vegetation index, which was significantly higher in girls than in boys during the school year.

Weakening sympathetic influences and return many hemodynamics to baseline at the end of the school year is probably due to the emotional factor "finite impulse". [8] The study of adaptive response to workload is closely related to a very significant problem for the school adaptation to static loads. Of the 3 types of stress in students during the training sessions the most tedious static components [4, 52].

The most natural reaction of systemic hemodynamics on static-mechanical effort is to improve all types of blood pressure [52, 55].

Maximum static load while sitting on the back and have to back muscles - extensors and pelvic girdle. Static load, in contrast to the dynamic increase both the maximum and minimum blood pressure. So responds to even slight static load equal to 30% of maximum compression force dynamometer, students of all ages. In the beginning, the changes hypodynamic indicators is less sharp than at the end of the year. Earlier this year, for example, a boy 8-9 years old at that static load increases the minimum pressure of 5.5% and a maximum pressure of 10%, and at the end of the year by 11% and 21% [13].

Multidirectional age and adaptations of cardio - vascular system in their school necessitated the consideration of both the assessment of health status, as well as the construction of a rational mode of the day student.

Only with proper organization of somatic-growth mode metrics will be accompanied by an adequate increase power operation of all parts of the cardiovascular system. [4]

2. RESULTS

2.1 Goals and objectives

The aim of the study was to study the dynamics of some indicators of the cardiovascular system, depending on the workload.

In this regard were as follows:

1. examine blood pressure and heart rate in students 1, 3, 5, 7 and 9 classes in a state of relative calm;

2. study the effect of workload on blood pressure and heart rate of students;

3. determine vegetative index of students to determine the prevailing influence of the sympathetic and parasympathetic nerves in the regulation of the cardiovascular system.

cardiovascular blood pressure

2.2 SUBJECTS AND METHODS

The objects of the study were students 1, 3, 5, 7 and 9 classes, ages 7 to 15 years. All students were identified in blood pressure relative rest (to school) in order to compare these figures with the standards of blood pressure in healthy schoolchildren. 306 students were surveyed.

The next part of the work was devoted to studying the effects of workload on the blood pressure and heart rate. The study was conducted in February (mid-third quarter), March (the end of the third quarter) and in April (beginning of the fourth quarter) for a week (Monday to Friday, from 8 to 13 hours).

Blood pressure and heart rate were used gauge, stethoscope and stopwatch. Blood pressure measurement was carried out by the method of NS Korotkov.

VI - vegetative index calculated using the formula Kerdo:where DD - diastolic blood pressure [56].

Were examined 21 student of the first class, 93 - the third, 97 - five, 77 - and 18 seventh - ninth grades. Of 306 students - 162 boys and 144 girls.

2.3 Results and discussion

2.3.1 Blood pressure in students in a state of relative calm

Data on standards of blood pressure in healthy children are controversial, especially among students 7 - 8 years. According to some authors [13, 20, 22, 49], systolic blood pressure of 7 - 8 year old children is 97 - 100 mm Hg and diastolic - 56 mmHg According to the data of others [24, 33, 34, 37], students aged 7 - 8 years systolic pressure ranges from 79 to 97 mm Hg, and diastolic - from 42 to 58 mmHg

In this regard, it was decided to investigate the blood pressure of pupils in a state of relative peace. The results are presented in Figures 1 and 2.

Analysis of the data showed that the children of both sexes with age blood pressure rises to 85 mm Hg at 7 years of age to 120 mmHg 14 - 15 years.

In the first grade (7 - 8 years) in systolic pressure of 95 to 100 mm Hg was recorded in 60% of boys. Systolic blood pressure 105 mm Hg was observed in 20% of children.

The students grade 3 systolic pressure ranges from 85 to 120 mmHg Pressure of 100 mm Hg 35.7% have children, 110 - 43.0%. In 7.2% of children had higher systolic blood pressure (115 - 120 mm Hg).

Students 5 and 7 classes of systolic blood pressure is 90 - 120 mm Hg However, the percentage of children with a pressure of 100 - 110 mmHg slightly lower than that of grade 3 students. A smaller number of children of this age with a pressure of 100 - 110 mmHg compared to the students of class 3, you can probably explain the onset of puberty.

In grade 9 the maximum blood pressure in males ranges from 110 to 120 mmHg Increased the percentage of children with a pressure of 120 mm Hg, compared with students 7 classes (30%).

The lowest systolic blood pressure in girls is 90 mmHg A significant number of girls 1, 3, 5 and 7 classes have pressure 100 mm Hg However, the girls class 1 the maximum value of systolic blood pressure less than 107 mm Hg, while in grade 3 students maximum systolic pressure is 115 mm Hg, and students have 5, 7 and 9 classes - 120 mm Hg

In grades 5 and 7 pressure of 120 mm Hg have 4% of girls among students in grade 9 - 25%.

Analysis of the data showed that the children of both sexes with age, along with the maximum pressure increases and the minimum pressure that rises to 45 mmHg at the age of 7 to 85 mm Hg 14 - 15 years (Fig. 3 and 4).

In 1st grade (7 - 8 years), the value of diastolic pressure of 45 to 50 mmHg was recorded in 80% of boys. Diastolic blood pressure of 60 - 70 mmHg observed in children.

The students of classes 3 and 5 diastolic pressure ranges from 50 to 80 mm Hg A greater percentage of children 3 class have the pressure of 60 mm Hg compared to grade 5 students. Among the students of grade 5 in 46% of children recorded pressure 70 - 80 mmHg

Boys 7th grade diastolic pressure is in the range of 60 - 80 mm Hg, and a greater percentage of the surveyed students are having a pressure of 70 mm Hg (38.9%).

In grade 9 diastolic pressure ranges between 60 - 85 mmHg In this slightly increases the percentage of children with a pressure of 70 mm Hg (Up 40%).

Diastolic blood pressure of 80 mmHg was recorded in 10% of students.

Girls Grade 1 diastolic pressure is in the range of 45 - 70 mmHg Accounted for the largest percentage of the value of diastolic pressure of 50 mmHg (45.5%).

Students Class 3 minimum pressure varies between 50 - 70 mmHg, with 62.2% of schoolgirls have diastolic pressure of 60 mm Hg

Among the students grade 5 10.6% have pressure 80 mmHg

Girls 7 and grade 9 diastolic pressure ranges from 60 to 80 mm Hg A greater percentage of grade 7 students (14.6%) have a pressure of 80 mm Hg, than students in grade 9 (12.5%) and a pressure of 70 mm Hg detected more often in girls in grade 9 and reached 62.5%.

2.3.2 The change of parameters of the cardiovascular system in children

Class 1 under the influence of the teaching load

According to the literature [4, 37, 44, 45], the workload impact on the cardiovascular system. From the beginning to the end of the school year, a decrease in blood pressure in students we studied the effects of workload on the functional state of the cardiovascular system of students 1, 3 and 5 classes, students on a common program in secondary schools. The studies were conducted in February (mid-third quarter), March (the end of the third quarter) and in April (beginning of the fourth quarter).

The results of the data presented in Table 5.

Analysis of the magnitude of blood pressure in grade 1 students in February showed that by the end of the week and the systolic and diastolic pressure is somewhat reduced. Systolic blood pressure in girls from Monday to Friday fell by 3.2, the boys - 2.9 mm Hg, diastolic blood pressure - by 2.4 and 2.1 mm Hg

At the end of the quarter (March) Monday to Friday, the pressure from below-moose more than in February. Systolic blood pressure in girls decreased by 3.6, and the boys - by 3.5 mm Hg and diastolic blood pressure - by 2.8 and 3.1 mmHg

Greater reductions in both systolic and diastolic blood pressure we observed in children in April. Systolic blood pressure in girls decreased by 5.3-moose, and in boys by 5.1 mmHg and diastolic - respectively by 4.5 and 4.7 mmHg

Blood pressure is measured at the boys and girls-Pone delnikam in February, March and April was the same. Pressure measured at the end of the week, there has been a downward trend from February to April.

The heart rate in boys 1 class in February and March was lower than that of girls. At the end of the year (April), it increased in males, reaching values of heart rate in girls. However, changes in heart rate during the week from Monday to Friday we have not seen in any of the survey period, which corresponds to some authors [4].

2.3.3 The change of parameters of the cardiovascular system 3 classes of students

Analysis of some hemodynamic parameters of cardio - vascular system in 3 classes of students is presented in Table 6.

Pupils Class 3 (ages 9-10 years), blood pressure is the same for girls and boys. In a state of relative rest systolic blood pressure in February ranged from 90 to 115 mm Hg and diastolic - 50 to 75 mm Hg.

Under the influence of workload tends to some reduction in blood pressure at the end of the week and the more pronounced the closer to the end of the school year (April) the study.

So, the girls in April systolic pressure Monday on the average 99,8 ± 3,0, boys - 99,6 ± 1,9 mmHg On Friday, the girls pressure dropped to 94,9 ± 2,4, boys - to 94,6 ± 1,6 mmHg

Diastolic pressure in the middle of the third quarter (February) for a week did not change, while at the end of the school year in girls, it decreased from 58.6 to 54.1 mm Hg, and the boys - 57.5 to 52.8 mmHg

Blood pressure is measured in February, March and April, on Mondays, as well as students' grade 1, was the same.

The heart rate in the middle and the end of the third quarter of C. for the week remained unchanged at the end of the school year decreased both in girls (from 78.5 to 74, 8 beats / min) and boys (from 82 to 78.5 beats / min).

2.3.4 Blood pressure and heart rate in grade 5 students

In the analysis of the five classes of blood pressure and heart rate was performed in 97 students (50 boys and 47 girls).

These results are shown in Table 7.

Grade 5 teaches children aged 11 to 12 years. At this age, boys pressure starts to rise and is higher than that of girls.

In the middle of the third quarter of the systolic blood pressure in girls averaged 104,7 ± 2,1, boys - 107,8 ± 2,6 mm Hg However, sex differences in the magnitude of blood pressure is not stable, and at the end of the school year blood pressure in boys and girls equally.

The students in this group, as well as the students in grades 3, at the end of the school year pressure from Monday to Friday down, boys and girls (average 6 mm Hg). This decrease is statistically significant (p <0,05). Heart rate is slightly higher in girls than in boys. By the end of the school year under the influence of the teaching load in heart rate decreases as the girls and boys.

2.3.5 Determination of vegetation index in students

When calculating the number of integrated indicators cardio - vascular tone can be described autonomic nervous influences and thus the nature of the vegetative regulation of blood circulation system.

The vegetation index (VI) Kerdo based on comparison values of blood pressure and heart rate:

VI = (1-DD / HR) * 100%, where

DD - diastolic blood pressure.

In vegetative balance in the regulation of cardio - vascular system Bu = 0. Positive index values indicate a shift in the balance of the sympathetic side, and negative - in the parasympathetic [56].

According to the blood pressure and heart rate obtained at baseline (February) and the end of the study (April), we calculated the average values of vegetation index. The data are presented in Tables 8 and 9.

After the birth of children is dominated mechanisms of sympathetic regulation of cardio - vascular system, resulting in significant heart rate at rest. As the child grows, this dominance is less pronounced, the tone of the parasympathetic effects. [57]

Table 8 shows that the students' class 1 (7-8 years) averages VI for boys and girls (31 and 32.7, respectively) higher than that of grade 3 students (9-10 years) - 24.6 and 29 1. The peculiarity of this age period (7-10 years) is the predominance of sympathetic regulation of cardio - vascular system.

Beginning in grade 5 (11-12 years), in the regulation of the circulatory system increases parasympathetic influence the nervous system, however, is still the predominant sympathetic.

Among students in grade 5 of 4 people found the vegetative balance, boys may experience the following ratio influences the sympathetic and parasympathetic nervous system, 18 and 6.5 for girls - 25.5 and 5, respectively.

It should be noted that cardio - vascular system 9th grade girls is more pronounced under the influence of the sympathetic nervous system. It can be concluded from the analysis of the average values ??of the VI, which was significantly higher in girls than in boys, which coincides with the results obtained G.F.Berenshteynom et al. [8] According to our data, the girls average positive values VI-13, 8, boys - 9.4.

Compared with students grade 5, the ninth, the influence of the parasympathetic nervous system, as evidenced by the average negative VI-9, 5. Autonomic balance was observed in 5 patients among patients.

Comparing the figures VI pupils in February and April, we can conclude the following: for the studied period in students of all age groups, a decrease of sympathetic and parasympathetic influences on the growth of cardiac function, as evidenced by the average values of positive and negative values of the vegetation index (Table 9. ).

Pupils 1 and 3 classes, a decrease VI in April compared with February. In April, students in grade 3 of 4 people established autonomic balance.

The students of classes 5 and 9 also decreases the positive values of VI and, conversely, an increase of negative values. In addition, a larger number of surveyed observed vegetative balance compared to February, which is probably due to the decrease sympathetic effects on the cardiovascular system as a result of fatigue, similar results were obtained E.Grinens and others [58].

2.3.6 Comparative characteristics of blood pressure and heart rate among students of classes 1,3 and 5

The analysis of the work showed that from class to class, a regular increase in blood pressure and slowing heart rate. However, students' class 1 (7-8 years), systolic and diastolic blood pressure greater in girls than in boys (the difference in pressure in February was 2.6 mm Hg). Students 3rd class (9-10 years), the pressure difference is smoothed out, but the girls, it remains higher than in boys (1.8 mm Hg), and since the 5th grade (11-12 years), the pressure boys gradually increased by 3.1 mm Hg).

Similar relations between blood pressure in students 7-17 N.M.Koreneva observed [59] and G.S.Yarovaya [60]. According to their data, the mean values of blood pressure were higher in boys than in girls under 11 years. From 12 to 15 years, these figures have girls than in boys, and from 16 years of blood pressure in boys again becomes higher. These data were obtained 30 years ago.

Some offset differences in mean blood pressure in boys and girls at an earlier date, probably can be attributed to early puberty modern children.

Study of the effect of workload on the functional state of the mid-dechno circulatory system of students' grades 1,3 and 5 showed that with-Pone delnika through Friday at various times of the year (February, March, April), a decrease in blood pressure, however, significant this reduction is only for systolic blood pressure and diastolic blood at the end of the year (Fig. 5, 8).

Prevalence of students' changes in blood pressure in the direction of reducing it to the end of the school year due to fatigue, were influenced by mental and static load, as well as lower the functional state of the cardiovascular system of students by the end of the school year. [61]

With age, there is a gradual decrease in heart rate (Figure 9.10). Thus, the pulse of pupils starting grade 1 ranged from 84 to 88 bpm. / Min, the students of class 3-heart rate was lower (79-83 bpm. / Min), and the students grade 5 - 74-80 beats / min, and, girls in different age heart rate higher than that of boys. However, we did not observe significant changes in heart rate under the influence of the teaching load for a week in February and March, and only at the end of the school year there was a slight decrease in its girls grade 5.

There was no clear heart rate dynamics under the influence of workload reported in [4.49].

Findings

Existing work leads to several conclusions.

1. Blood pressure with age in students regularly increases and heart rate decreases.

2. Blood pressure differences by gender were found in groups of 7-8 and 11-12 years: the students grade 1 pressure is greater for girls than for boys, 5th grade students, on the contrary, the pressure is greater in boys than in girls.

3. Teaching load causes a slight decrease in blood pressure and heart rate at the end of the school year.

4. Cardio - vascular system students 1,3 and 5 classes is more pronounced under the influence of the sympathetic nervous system. Weakening sympathetic effects on cardiovascular activity observed in students in grade 9.

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