Human blood is a tissue composed of several cells, being fundamental to life. The circulation of blood through the veins, arteries and capillaries happens due to the heart beats and aims to transport oxygen, nutrients and hormones to all the cells of the body.
The amount of blood cells tells a lot about body health, with values above or below the reference values indicative of diseases such as anemia, leukemia, inflammation or infections. The test performed to evaluate the amount of blood cells is the blood count, which does not need fasting to be performed, but it is advisable to avoid alcoholic beverages 48 hours before the exam and avoid performing physical activities 1 day before, as they may interfere with the results. See what the hemogram is for and how to interpret it.
Functions of blood
Blood is a fluid substance that has fundamental functions for the proper functioning of the organism, such as:
- Transport oxygen, nutrients and hormones to the cells;
- Defend the body against foreign substances and invading agents;
- Regulation of the organism.
In addition, the blood is responsible for removing from the tissue substances produced in cellular activities and that should not remain in the body, such as carbon dioxide and urea.
Blood Types
Blood can be classified according to the presence or absence of antigens A and B on the surface of the red blood cells. Thus, 4 blood types can be defined according to the ABO classification:
- Type A blood, in which red blood cells have antigen A on their surface and produce anti-B antibodies;
- Type B blood, in which red blood cells have B antigen on their surface and produce anti-A antibodies;
- Type AB blood, in which red blood cells have both types of antigen on their surface;
- Type O blood, in which red blood cells have no antigens, producing anti-A and anti-B antigens.
Blood type is identified at birth by laboratory analysis. Learn all about your blood type.
Blood components
The blood is composed of a liquid part and a solid part. The liquid part is called plasma, 90% of which is only water and the rest is composed of proteins, enzymes and minerals.
The solid part is composed of figurative elements, which are cells such as red blood cells, leukocytes and platelets and which play key roles for the proper functioning of the organism.
1. Plasma
Plasma is the liquid part of the blood, being viscous and yellowish in color. Plasma is formed in the liver and the main proteins present are globulins, albumins and fibrinogen. Plasma has the functions of transporting carbon dioxide, nutrients and toxins produced by the cells, as well as being responsible for transporting drugs through the body.
2. Blood cells or erythrocytes
Red blood cells are the solid red part of the blood that functions as the oxygen transport through the body, since it has hemoglobin. The red blood cells are produced by the bone marrow, they last about 120 days and after that period they are destroyed in the liver and the spleen.
The amount of erythrocytes in 1 cubic mm in man is about 5 million and in women it is around 4.5 million when these values are below expected the person may be with anemia. This count can be done through the examination called the hemogram.
3. Leukocytes or white blood cells
Leukocytes are responsible for the defense of the body and are produced by the bone marrow and lymph nodes. Leukocytes are composed of neutrophils, eosinophils, basophils, lymphocytes and monocytes.
- Neutrophils: They serve to fight small inflammations and infections caused by bacteria or fungi. This indicates that if the blood test is seen an increase in neutrophils, the person may be with some inflammation caused by a bacterium or fungus. Neutrophils encompass bacteria and fungi, rendering these aggressive agents inoperable, but they later die of pus. If this pus does not leave the body it causes swelling and abscess formation.
- Eosinophils: They serve to combat parasitic infections and allergic reactions.
- Basophils: They serve to fight bacteria and allergic reactions, they lead to the release of histamine, which leads to vasodilation so that more defense cells can reach the region necessary for the elimination of the invading agent.
- Lymphocytes: They are more common in the lymphatic system but are also present in the blood and are of 2 types: B and T cells that serve for antibodies that fight viruses and cancer cells.
- Monocytes: They can enter the bloodstream and are specialized in phagocytosis, which consists of killing the invader and presenting a part of that invader to the T lymphocyte to produce more defense cells.
Understand more about what leukocytes are and what the reference values are.
4. Platelets or thrombocytes
Platelets are the cells responsible for ceasing bleeding with the formation of blood clots. Each 1 cubic millimeter of blood should contain 150, 000 to 400, 000 platelets. When the person has fewer platelets than normal, there is a difficulty to stop bleeding, and there may be bleeding that can lead to death, and when there are more platelets than normal there is a risk of thrombus formation that can move around blocking some blood vessel that can cause infarction, stroke or pulmonary embolism. See what high and low platelets mean.
