The number, composition and general properties of the blood

Blood – opaque adhesive red liquid, salty taste which consists of two parts: the plasma and formed elements – erythrocytes, leukocytes and platelets.

The amount and composition of the blood vary continuously, but differ relative constancy of each species. The amount of blood, the structure and the number of formed elements, the chemical composition of the plasma from different animal species differ.
The amount of blood in humans is an average of 7% of the weight of the entire body (with the oscillations 5-9%), the horse – 9.8%, the cow – 8.0% in sheep – 8.2%, pig – 4 6%.

A person in normal whole blood at rest is divided into two parts. One part of the blood, which is equal to 40-50% of its mass, circulates through the blood vessels of the whole body – the circulating blood and the rest is in the depot – deposited blood.
Deposited concentrated blood in the capillaries of the spleen, liver and subcutaneous tissue and almost immiscible with the circulating blood.

Increased body temperature, muscle work, choking, inhalation of carbon dioxide, strong emotions – emotions, administration and the blood of adrenal hormones – adrenaline – call to increase the number of circulating blood by the blood ejected from the depot.

According to the calculations in the spleen stagnates 16%, 20% in the liver and skin in 10% of the mass of blood.
Significance of blood deposit is that a decrease in the amount of circulating blood due to its stagnation in the depot falls load on the heart during rest sewn. And when blood loss and the above conditions (muscular work, and so on. D.), In cases of necessity and emergency, increasing the number of circulating blood, her ejection reflex occurs from the depot into the blood stream.
Please note that blood deposited in mechanical strength and causes water absorption of the plasma into the tissue contains more formed elements than the circulating blood. Thus, the number of red blood splenic relates to their number in the circulating blood as a 3: 2.

Therefore deposited blood flow in the general bloodstream causes not only an absolute, but a relative increase in a blood erythrocyte count and hemoglobin.
Intake of liquids for a short time increase the total amount of blood, since intestinal absorption after water enters the bloodstream. When depriving the body of water, especially when the amount of blood loss of blood is temporarily reduced.
The rapid decrease in blood volume in the blood loss is more dangerous than the loss of formed elements, since it is accompanied by a drop in blood pressure. Slow loss of even large quantities of blood is less dangerous than rapid loss of smaller amounts of blood. Slow loss to all the red cells may not even lead to death. Rapid loss during arterial bleeding 1/3 – 1/2 of the total number of blood leads to death.


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The number, composition and general properties of the blood