How much blood is in a person?
Blood is a liquid connective tissue that consists of plasma and blood cells (red blood cells, white blood cells, platelets). Blood transports important substances for the body, gases and metabolic products. In addition, the liquid red fabric performs a protective function. Today we consider how much blood is in a person and how its volume is determined.
How many liters of blood in the human body
The average blood volume in the body is four to six liters, which is six to eight percent of a person’s weight. That is, if the body weight is seventy kilograms, then the blood in the body of this person is about five and a half liters.
Ten percent blood loss is considered acceptable. If you lose thirty percent of the blood - there is a danger to the body. With a loss of fifty percent, death usually occurs.
Often, blood loss leads to diseases (for example, anemia).
Read our article How many liters of blood are in a person.
Information about the blood group and the Rh factor can be found in the article What are blood types.
What affects blood volume
First, the amount of blood depends on human activity. For example, during heavy physical exertion, blood enters the body from the so-called “storage rooms” (blood reserves are located in the vessels of the liver and spleen, as well as in the subcutaneous tissue). In case of blood loss, reserve blood also enters the body.
Secondly, the volume of blood increases with the intake of fluids into the body. However, for a long time the water does not linger in the human body, since the excess takes the kidneys.
Methods for determining the amount of blood in the body
To determine the blood volume, a special dye is introduced into the blood vessels, which is absolutely harmless to the body. Then wait for some time until the substance is evenly distributed in the blood. After that, a portion of blood is taken for analysis, where the concentration of the administered substance is determined. Based on the amount of fluid injected, the total blood volume in the body is calculated.
In this case, blood is taken from a person, and then red blood cells are separated from the plasma. Next, the red blood cells are placed in a solution containing radioactive phosphorus.Then the “labeled” red blood cells are injected back to the person. After the substance is distributed, the blood is again taken for analysis and the total amount of blood is calculated by calculation based on the concentration of the radioactive substance.
In case of blood loss, blood diseases or cancer, a person needs a blood transfusion. Healthy blood is provided by donors - people who voluntarily donated their blood or plasma. When blood is taken, a thorough medical examination of the volunteers is conducted. Moreover, people who have been ill with certain diseases are not allowed to donate blood (for example, viral hepatitis, HIV, AIDS, asthma, etc.).
A person can donate four hundred fifty milliliters of blood or six hundred milliliters of plasma at a time. In this case, the blood is donated within ten minutes, and the plasma is taken 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, speak about its benefits:
- Unloading of organs;
- blood renewal;
- rejuvenation of the body;
- reducing the risk of developing certain diseases (for example, heart disease, atherosclerosis, indigestion).