The work of the heart ensures the functioning of all organs of the body. Due to its contractions, the blood constantly moves to biological tissues, where it gives off oxygen and removes metabolites, carbon dioxide. Returning through the veins, she goes to the lungs, where it is again saturated with oxygen. With each new systole, this cycle maintains a continuous blood supply, which can be disturbed by arrhythmia, a decrease or increase in the frequency of heart contractions. And only on the functional needs of the body will depend on what should be the heartbeat at the current moment.
Heart rate differences
The heart rate is one of the most important parameters of the human body. It depends on the current functional state, rest or motor activity, and on the size of the heart and body. The smaller the size of the organ, the higher the frequency of contractions.
That is why in children the heart rate is always higher than in adults, since the morphological proportions change during the growth of the body and body. In particular, the heart increases in size at first more slowly than other parts of the body, and then partially compensates for the lag. For this reason, the child's heart rate is first higher than that of an adult, and later the rate gradually decreases.
Adult Heart Rate
A person at rest often experiences bradycardia, and at the peak of the functional load, the heart rate reaches 160 beats per minute without loss of minute volume of blood supply. This is achieved by severe hypertrophy of the left ventricle, which provides the ability to maintain effective expulsion of the systolic volume.
But if you do not consider the extreme border, then what should be the heartbeat normal? In fact, the norm is in the range from 60 to 90 ventricular contractions per minute. And this is not a strict biological constant, but just an average medical value. The constant is the level of the body's need for blood supply, and if any deviations from it are observed, then the heart rate will be changed.
Baby heart rate
In children, the heart rate is significantly higher than in adults, which is associated with a mismatch in the size of the heart cavities and morphological parameters of the body. Because of this, in order to ensure effective blood supply, the body is forced to make the heart contract more often. In the fetus, the norm limits are at the level of 120-160 beats per minute, in the newborn - from 110 to 170, and at the age of 1 year the heart rate is normally 100-160 beats per minute.
From the first to the second year of life, the norm limits are at the level of 96-150, and from 2 to 4 years - from 90 to 140 beats per minute. At the age of 4-6 years, heart rate is 86-126 beats, at 6-8 years - 78-118 contractions per minute. Upon reaching the age of 8-10 years, the normal heart rate drops to levels of 68-108, and from 12 years old, the child's heart rate complies with the norms of an adult.
Blood supply intensity
Only on physical activity, the state of the humoral systems of the body and morphological size depends on a comfortable heart rate. These mechanisms determine what should be the normal heartbeat in a particular patient. The standards adopted in the medical community are not individually adapted for each person, but are average statistics at which the comfortable functioning of all body structures is noted.
The effective heart rate is the number of heart contractions that ensures the necessary intensity of blood supply to organs and tissues necessary for comfortable life activity. For example, the current figure is 70 beats per minute. And at rest this is enough to provide the whole body with oxygen and nutrients. If the body goes into another functional state, for example, a person stands up and runs, the heart rate will increase, since the load requires an increase in the intensity of skeletal muscle nutrition.
In another situation, when the body goes from sleep to sleep, the functional load becomes even lower, because of which the rate of blood supply intensity also decreases. Since tissues operate in a mode of minimal energy consumption, the intensity of the heart to maintain their vital activity in this state should be minimal. This determines what the heartbeat should be at the current moment. And at rest, the frequency will be at the lower limits of the norm or fall even lower, provided that the most important electrophysiological constants are preserved (action potential and width of electrocardiographic intervals).
Rationale
It was indicated above what kind of heartbeat a person should have and on what factors it depends. However, why the norm is just such, it should be explained in more detail. So, the heart rate depends on the required level of blood supply intensity. If it is low, and the tissues experience oxygen starvation, then as a result of stimulation of the cardiovascular system, the number of contractions and the minute volume of blood supply will be increased.
The norm of the heart rate is observed at the moment when the volume of systolic ejection directed into the circles of blood circulation with each contraction is sufficient for blood supply to the body structures. If necessary, increase the intensity of blood supply, the frequency will be increased to acceptable values, which are limited by the cessation of the increase in minute volume of blood circulation.
Functional dependence of heart rate
An increase in heart rate will lead to an increase in the intensity of blood supply only to a certain limit, above which the effectiveness of this mechanism is greatly reduced. This is due to two mechanisms. The first is diastolic filling of the heart: the higher the heart rate, the less effectively the cavity of the heart is filled. Therefore, less blood enters the ventricles, and instead of an increase in the minute volume of blood circulation, a significant decrease will be noted.
The second mechanism is effective pushing. The higher the frequency and the lower the filling of the ventricular cavity, the less effective will be the expulsion of a portion of blood from the ventricular cavity into the arteries. Therefore, an increase in heart rate leads to an increase in the intensity of blood supply only to a certain functional limit.
The balance between these two mechanisms and the functional needs of the body determines how an adult should have a heartbeat at a certain point in time. Above it, increasing the heart rate will not allow the electrophysiological system of the myocardium, failures and malfunctioning of which occur only with pathology (arrhythmias).