Blood is a liquid connective tissue that consists of plasma and blood cells (erythrocytes, leukocytes, platelets). Blood transports substances, gases and metabolic products important for the body. In addition, liquid red fabric performs a protective function. Today we will look at how much blood is in a person and how its volume is determined.
How many liters of blood are in the human body
The average volume of blood in the body is four to six liters, which is equal to six to eight percent of a person's weight. That is, if the body weight is seventy kilograms, then the blood in this person’s body is about five and a half liters.
Ten percent is considered acceptable blood loss. If you lose thirty percent of your blood, there is a danger to the body. A loss of fifty percent usually results in death.
Often, blood loss leads to diseases (for example, anemia).
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You will find information about blood type and Rh factor in the article.
What affects blood volume
Firstly, the amount of blood depends on human activity. For example, during heavy physical exertion, blood enters the body from the so-called “reserves” (blood reserves are located in the vessels of the liver and spleen, as well as in the subcutaneous tissue). When blood loss occurs, reserve blood also enters the body.
Secondly, blood volume increases with the intake of fluids into the body. However, water does not stay in the human body for a long time, since the excess is taken by the kidneys.
Methods for determining the amount of blood in the body
Colloidal solution
To determine the volume of blood, a special dye is injected into the blood vessels, which is absolutely harmless to the body. Next, wait a while until the substance is evenly distributed throughout the blood. After this, a portion of blood is taken for analysis, where the concentration of the administered substance is determined. Based on the amount of fluid administered, the total volume of blood in the body is calculated.
Radioactive tracers
In this case, blood is taken from a person, and then the red blood cells are separated from the plasma. Next, the red blood cells are placed in a solution containing radioactive phosphorus. The “tagged” red blood cells are then injected back into the person. After the substance is distributed, blood is taken again for analysis and the total amount of blood is calculated computationally based on the concentration of the radioactive substance.
Donation
In case of blood loss, blood diseases or cancer, a person needs a blood transfusion. Healthy blood is provided by donors - people who voluntarily donate their blood or plasma. When blood is collected, volunteers undergo a thorough medical examination. Moreover, people who have had certain diseases are not allowed to donate blood (for example, viral hepatitis, HIV, AIDS, asthma, etc.).
A person can donate four hundred and fifty milliliters of blood or six hundred milliliters of plasma at a time. In this case, blood is donated within ten minutes, and plasma is collected for half an hour or more.
There is an opinion that donation is harmful to the human body. However, doctors do not consider the procedure dangerous, but, on the contrary, talk about its benefits:
- Unloading of organs;
- blood renewal;
- rejuvenation of the body;
- reducing the risk of developing certain diseases (for example, heart disease, atherosclerosis, digestive disorders).
In addition, thanks to regular blood donation, resistance to blood loss is developed, and excess blood is removed from the body,
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Blood is an essential component of the internal environment of the human body. Due to its constant movement through the vessels, metabolism is carried out in organs and tissues.
Compound
Blood is a liquid connective tissue, which includes cells or formed elements (leukocytes, erythrocytes, platelets) and intercellular substance (plasma).
On average, formed elements account for about 40-45% of blood, and plasma - 55-60%. Laboratory analysis shows all deviations from the norm and indicates the presence of a particular disease. Depending on how many liters of blood there are in a person, the number of its constituent elements may be different. Its composition may also be influenced by health status and geographic location. For example, when you rise to a height, the number of red blood cells increases significantly. Residents of the Caucasus or Switzerland have 50 percent more red blood cells than England or other highland areas. Blood moves through the vessels at a speed of 40 kilometers per hour.
Functions
The main functions of blood are determined by its composition.
Due to plasma, which is an aqueous solution of proteins, fats, carbohydrates, amino acids, vitamins, hormones, as well as inorganic (mineral) substances, the function of transporting water and nutrients to tissues and organs and removing metabolic products is carried out. Thanks to the viscosity that proteins impart to the plasma, blood pressure is maintained at the desired level. A certain composition of plasma ensures the constancy of its internal environment in the body. Each blood element also performs a specific function:
Erythrocytes (red blood cells) carry oxygen throughout the body. They cause the red color of blood.
White blood cells (colorless cells) perform the function of protecting the body by fighting foreign bodies (including viruses, bacteria, cell fragments, particulate matter, allergens and toxins). There are several types of leukocytes. Each of them is responsible for the destruction of a certain type of foreign body. Based on their ratio, leukocyte formulas are compiled, which indicate the presence of a particular harmful agent in the body. White blood cells produce certain antibodies that make the body immune to infectious diseases. The doctrine of human immunity, as well as the creation of vaccinations and serums to combat severe infections, is based on this property.
Platelets are blood cells that provide blood clotting. This ability allows you to avoid large blood losses as a result of various types of injuries. Disruption of the activity of these cells is often associated with genetic changes and leads to dire consequences, when even the most harmless cut or scratch can become deadly.
Blood groups
Human blood is divided into 4 groups: the first - O, the second - A, the third - B, the fourth - AB. This classification was introduced in 1900 by K. Landsteiner, it is called the ABO system. This division of blood is based on the content or absence of erythrocyte antigens A and B, as well as plasma antibodies A and B. Blood transfusions are carried out taking into account the compatibility of the groups with each other. Each group, in turn, can be of two types: Rh-positive and Rh-negative. This feature is very important for couples planning to have a child, since in some cases Rh conflict may arise. As a result, pregnancy and gestation become problematic.
How many liters of blood does a person have? Factors influencing the indicator
The question of how many liters of blood is in a person cannot be answered unambiguously. It is believed that this indicator depends on the individual characteristics of the body, body weight, age, gender and physical condition of the body. In general, the norm for an adult is approximately 4-6 liters (6-8% of the total body weight). Thus, if a person has a mass of 65 kg, then he will have approximately 3.9-5.2 liters. Most of the blood constantly circulates through the vessels, and some of it (up to 40%) is located in the so-called “blood depots” of the body. These are the liver, spleen, lungs, skin, etc. With strong muscle loads, large blood losses, and a decrease in atmospheric pressure, it leaves a kind of depot.
The amount of blood in a person
In women, the volume of circulating blood is 4-4.5 liters, in men - 5-5.5 liters. Its amount may vary depending on the volume of fluid drunk, during menstruation and pregnancy, with blood loss due to injuries and operations, and with heavy physical exertion. The amount of blood in children of different age groups differs significantly. In relation to body weight, the following indicators are considered normal:
- 15% - in newborns;
- 11% - in one-year-old children;
- 9% - in adolescence.
Safe minimum
How many liters of blood should a person have so that there is no threat to life? It is believed that if a person loses 2-3 liters, he dies. This can happen for many reasons. Among them are sudden and heavy bleeding, operations and the postoperative period, treatment of various diseases, hemodialysis.
To save lives, in medicine they often resort to the procedure of donor transfusion. A person who donates his blood to help others is called a donor. It is believed that the one-time safe volume that is taken from him is 450 ml of blood, and plasma - 600 ml. You can donate plasma no more than 2 times a month, and blood no more than 1 time a month. During this time, the quantitative and qualitative blood composition is completely restored. Each institution that collects donor blood compiles its own database. There are a number of diseases for which it is contraindicated to be a donor. To identify such facts, everyone's blood is taken for a special analysis.
Dangerous situations
A blood loss of 20-40% of the total is considered life-threatening. Most people experience heart problems, low blood pressure, breathing problems, dizziness or fainting. The following are considered external manifestations: pale skin and coldness of the upper and lower extremities. With blood loss of 50 to 70 percent, convulsions and agony begin, and the chances of survival approach zero. An important factor in blood loss is its speed. For example, a sudden loss of blood in the amount of 2-3 liters in a short period of time is fatal, but a prolonged loss of blood will not be so. However, the second case may be hidden (internal bleeding), which is sometimes difficult to diagnose and entails a huge threat to the bleeding organ and the body as a whole. The symptoms in this case are similar to those described earlier in this article.
Recovery
Self-regeneration of blood is allowed with a loss of no more than 30 percent.
Otherwise, a donor blood transfusion is required. For quick recovery, you need to eat foods rich in iron, including beef and red fish, liver, and also drink a lot. Raisins, dried apricots and nuts are very useful in this regard. Among the drinks, pomegranate juice and a small amount of red wine, tea with sugar and milk are of particular value. Complete self-healing of the blood occurs within two weeks. As a result, it turns out that how many liters of blood a person had before blood loss is approximately the same after the recovery period.
Of course, everyone knows what blood is, what it consists of and what its main functions are; as a rule, all these issues are studied at the school curriculum level. However, not everyone knows how many liters of blood there are in a person. Without blood, which consists of red blood cells, leukocytes, plasma and platelets, our body is, in principle, unable to exist and perform its functions, since it is it that provides the necessary connection between all organs. If the composition of this liquid undergoes any changes, then health indicators begin to change, and this applies to both an adult and a child.
The blood level in an adult and already mature person remains practically unchanged. On average, the human body contains approximately five liters of blood circulating through the vessels and arteries. So, if a person weighs 50 kg, then his blood volume should not be less than three liters, respectively, with a weight of 60 kg - 4 liters, and with a weight of 70 kg - five. It is quite difficult to indicate more accurate indicators without appropriate research, since the individual characteristics of the body are different for all people. In addition, according to most experts, the level of blood in the body can increase and this is affected by the liquid that a person consumes.
The bulk of the blood constantly circulates throughout our body, ensuring the timely delivery of oxygen and nutrients to the cells. A certain percentage of excess blood is redistributed to the skin or simply eliminated from the body naturally, after being processed in the kidneys. It is known that the volume of circulating blood through the veins and arteries of the stronger half of humanity is greater than that of women; on average, the figures differ by one liter.
Do not forget that blood can also perform a protective function, for example, leukocytes and certain substances contained in plasma rid our body of toxins and microbes that inevitably enter it. In terms of composition, blood is nothing more than a liquid circulating in the body of adults and children, which ensures the normal functioning of the entire body.
Today, anyone weighing 50, 60 or 70 kg can find out the exact volume of blood in their body by undergoing a safe test that includes the following steps:
- A special contrast agent is injected into the body of adults and children, which is not removed from it immediately, but after a certain amount of time. A specialist monitors the dosage of such a substance, and he is also responsible for determining it based on weight. It should be noted that the concentrate is a colloidal dye that is absolutely harmless not only for an adult 60 kg person, but also for a child - it does not negatively affect the composition and basic function of the blood.
- After the concentrate is evenly distributed throughout the body, you can begin drawing blood to determine its exact volume. With the help of the latest technologies in a modern laboratory, this is not difficult to do, and after some time you will have research results in your hands, detailing the percentage and composition of leukocytes and erythrocytes.
In addition to this method, another equally effective method is used in medical practice, but to some it may seem less safe. The method is that an artificial radioactive isotope is injected into the blood; after certain manipulations, the doctor can accurately name the number of red blood cells and calculate the volume. It is not so important how much you weigh, 50, 60 or 70 kg, finding out the exact volume of blood circulating in the body is easy and simple, thanks to modern research methods.
Extreme indicators
Both adults and children have their own certain indicators, if they are too low, the loss of red fluid can cause death. A minute loss of two or more liters of blood may well cause death, which is why it is so important to try to stop it by all means. Blood loss can provoke such a dangerous disease as anemia. An interesting fact is that representatives of the fairer sex tolerate blood loss more easily than men.
The most dangerous thing is rapid bleeding, when in just a few minutes a person loses a significant amount of red liquid. If appropriate measures are not taken urgently, the person will die, and a transfusion will no longer help.
Remember that during blood loss, every minute counts, so you always need to act quickly and clearly - you must not give in to panic, because someone’s life may depend on it. For large losses, such as during internal surgery, blood transfusions are used successfully, usually requiring at least eight liters, even if the patient weighs only 60 kg. Each patient has his own blood type and Rh factor, which is naturally taken into account during transfusion, otherwise it will not be able to perform its basic functions. Sometimes transfusions need to be done if adults or children have special diseases.
Benefits of donation
Many, for one reason or another, had to act as a donor and donate their blood or plasma, some had their own reasons for this, while others simply do this for charity for the sake of sick children. Of course, you won’t be able to just come to the blood transfusion center without an appropriate examination; first you will need to see doctors such as:
- Therapist.
- Venereologist.
- Dermatologist.
Only after you receive permission from each specialist, you can become a donor, and it does not matter whether you weigh 50 or 60 kg, the volume of red liquid taken will not exceed 450 ml - this is the indicator that will not affect the functions of the body.
All new arrivals are necessarily checked against the database, and those who have recently suffered from certain diseases may not be admitted at all. Red liquid is donated no more than once a month, but plasma is allowed to be donated twice. The blood collection procedure takes no more than ten minutes, there is nothing complicated about it. If you come to donate plasma, you will have to lie on the couch for at least thirty minutes.
In addition to transporting various nutrients and oxygen from one organ to another, with the help of blood circulation in the body, metabolic products and carbon are transferred to those organs through which waste products are removed: kidneys, intestines, lungs and skin. Blood also performs protective functions - white and protein substances contained in plasma are involved in neutralizing toxins and absorbing microbes that enter the body. Through the blood, the endocrine system regulates all vital functions and processes, since those produced by the endocrine glands are also transported by the bloodstream.
Lymph, tissue fluid and blood make up the internal environment of the body; the constancy of its composition and physicochemical characteristics is supported by regulatory mechanisms and is an indicator of health. In the event of pathological or inflammatory processes associated with a particular disease, the composition of the blood also changes, so it is the first thing the doctor will need to make a diagnosis.
Dangerous for a person is a rapid decrease in the amount of blood, for example, in the case of an open wound, which causes a sharp drop in blood level.
Since the composition of blood contains formed elements in suspension, its composition is determined by centrifugation. In human blood it is about 55-58%, and the remaining formed elements are from 42 to 45%, and there are slightly more of them in blood than in blood.
blood is found in the human body
Currently, the amount of blood circulating in the human body is determined with a fairly high degree of accuracy. For this purpose, a method is used when a dosed amount of a substance is introduced into the blood, which is not immediately removed from its composition. After some time it is evenly distributed throughout the entire circulatory system, a sample is taken and its concentration in the blood is determined. Most often, a colloidal dye that is harmless to the body, for example, Congo Rot, is used as such a substance. Another way to determine the amount of blood in the human body is to introduce artificial radioactive isotopes into the blood. After some manipulations with the blood, it is possible to calculate the number of red blood cells into which the isotopes have penetrated, and then, based on the value of the radioactivity of the blood, its volume.
If excess fluid forms in the blood, it is redistributed to the skin and muscle tissue, and is also excreted through the kidneys.
As it was found out, on average the amount of blood is about 7% of the weight, if your weight is 60 kg, the blood volume will be equal to 4.2 liters, 5 liters volume circulates in the body of a person weighing 71.5 kg. Its volume can vary from 5 to 9%, but, as a rule, these fluctuations are short-term in nature and are associated with the loss of fluid or, conversely, its introduction into the blood, as well as with heavy bleeding. But the regulatory mechanisms operating in the body maintain the amount of total blood volume in it constant.
The amount of blood in a person ranges from 6 to 8% of body weight, i.e. 4-6 liters. Women have approximately 1-1.5 liters less blood than men. It has been established that on average the amount of circulating blood corresponds to 60 – 70 ml/kg of body weight.
In a newborn, the total amount of blood reaches 15% of body weight. It should be noted that this value is largely determined by how quickly after the birth of the child the placental vessels were ligated. By the age of six months, blood mass averages about 11-12% of body weight, and even by the end of the first year of life it corresponds to an average of 10%. Only by the age of 11-12 years, the amount of blood in a child becomes the same percentage as in adults. Boys, like men, have a slightly larger total amount of blood than girls.
Under resting conditions, the volume of circulating blood is constant, despite the consumption of water and its absorption from the stomach and intestines. The latter is explained by the strict balance between the intake and excretion of water from the body. The normal volume of circulating blood is called normovolemia; a decrease in the amount of circulating blood, which, in particular, is observed after blood loss, severe physical activity, work in hot workshops and excessive sweating (excessive enthusiasm for the sauna or Russian bath), is designated as hypovolemia, increase (this occurs when taking a very large amount of liquid) – hypervolemia, or plethora.
It should be noted that of the total mass of blood under normal conditions, 2/3 of it is in the veins and only 1/3 in the arteries. Since the amount of blood flowing through the veins to the heart must be equal to the amount of blood flowing from it through the arteries, it becomes clear that 1/3 of the blood is excluded from the circulation. This blood was called deposited. It represents a reserve that can be quickly released into the circulation for a better supply of oxygen to tissues.