Blood: components, functions and the circulatory system

Blood is a vital liquid tissue for the body. It is responsible for traveling throughout the body through blood vessels. Next, they transport the cells that are necessary to fulfill vital functions, such as forming substances, defending aggressions and breathing.

The amount that each person owns is related to different aspects that are mentioned later. Likewise, it is also necessary to know that is the transporter of nutrients from the digestive system.

What is blood?

It is formed mainly of living tissue that is made up of solids and liquids. In the case of the liquid substance, it is known as plasma and its composition is proteins, salts and water. In fact, half of the human body is filled with plasma. On the other hand, in relation to the solid part, it contains platelets, white blood cells and red blood cells.

There are four types of blood and they are A, B, AB and O. In addition, it is also divided into Rh positive or Rh negative. For example, if your blood type is A, it would have to be either A positive or A negative. It is important to know what type you belong to. Especially if you require a blood transfusion at some point. As well as, it is decisive if you are pregnant, since there may be incompatibility between the baby and your body.

With various blood count tests. In addition, the blood test helps specialists to find possible conditions or diseases. They are also ideal for verifying that organs are working properly and that treatments are doing their job. Among the most common blood problems are platelet disorders, poor clotting, and blood clots.

Composition of blood

It is basically made up of 3 types of cells, such as platelets, white and red blood cells. Besides that plasma is also present. We detail each of them below.

Red blood cells

Also known as erythrocytes or red blood cells, they have the objective of transporting oxygen. This route is made from the alveoli of the lungs to the tissues of the body. Also, the protein located within red blood cells and that binds with oxygen is called hemoglobin. This substance is red and is responsible for providing the characteristic color. It is estimated that there are between four and five million red blood cells for every cubic millimeter.

White blood cells

They are also called or known as leukocytes, they have the purpose of defending the body. They are responsible for nullifying or destroying harmful agents that penetrate the body. Among these, we can mention fungi or viruses, bacteria, among others. The white blood cell count is between six and seven thousand for every cubic millimeter.


They are responsible for carrying out part of the blood clotting and are known as thrombocytes. It means that they are those that inhibit bleeding and, at the same time, are necessary for proper wound healing. His calculation is estimated between two hundred and three hundred thousand platelets for every cubic millimeter of blood.


It is immersed in blood cells, it is composed of large amounts of proteins. Albumin, which is responsible for transporting all drugs and hormones to the tissues. There are also immunoglobulins, which is what protects you from conditions. Finally, the coagulation factors that are the ones that serve as defense, in the company of platelets, against possible bleeding.

Vital functions

This vital of the body, is driven by the heart, travels through the capillaries and arteries of the body. After that, they return to the veins to go through the process of pulmonary oxygenation and then become arterial blood again. In the development of this cycle, the blood substance fulfills the following functions:

Respiratory function

It is about the transportation of oxygen and much of the carbon dioxide that is responsible for taking the air from the lungs.

Nutritive function

It is in charge of everything related to the contribution of substances that come from digestion.

Defensive and immune function

Keeps the body protected with the help of white blood cells and leukocytes.

Excretory function

It is responsible for collecting all the waste and residues that will later be eliminated.

Conveyor function

It corresponds to the hormones and secretions that are produced by the different glands.

Regulatory function

It is what maintains the balance of body temperature, body water, among others.

Blood circulation

The body’s circulation system performs two complementary and distinct types, such as minor and major circulation. The greater circulation is in charge of spreading the clean and oxygenated liquid from the heart to the tissues, organs and cells. The process starts from the left ventricle via the aorta, which then divide into tiny arteries. After all this process, an exchange takes place between oxygen and carbon dioxide until it reaches the veins.

In another sense, the pulmonary or minor circulation is responsible for storing blood waste. They then divert it from the right side of the ventricle, reaching the lungs through the pulmonary artery. The objective of this is that it can be renewed again. After it is oxygenated, it travels to the heart through the four veins in the lungs. The circulatory process is very complex, therefore, there are numerous studies that are done to understand what the body does to achieve it.

What is the amount of blood in the human body?

People have different amounts of blood, some more than others. Which is determined based on sex, height and weight. For example, an adult man usually has between 4.5 and 6 liters in his body. In addition, a drop of blood takes up to sixty seconds to travel through the body to reach the heart. All this will depend on the physical activity that the person is doing at a certain time.

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