Blood

The blood is a conjunctive Tissu present at the majority of the animal advanced. This Liquide is used to diffuse the Oxygène and the nutritive elements necessary to the vital processes of all fabrics of the body, and to evacuate waste such as nitrogenized carbon dioxide or waste. It is also used to bring to fabrics the cells and the molecules of the Immune system, and to diffuse the Hormones in all the organization.

At the Vertebrate S, blood is of color red. Blood becomes red clear during oxygenation in the lungs, then it circulates in the arteries. It becomes then red dark after having lost its oxygen with the profit of fabrics. While observing many veins, one notices that it appears blue. The skin acts like a filter, letting pass only blue, but this one is quite red, even inside the veins.

Blood is put moving by the Cœur which allows its circulation in all the organization. It passes by the Poumons to take care in Dioxygène and to evacuate carbon dioxide (small circulation), and then circulates through the body via the blood-vessels (great circulation). It releases its oxygen and deals with carbon dioxide on the level of the capillary blood S which are the smallest blood-vessels of the organization. In its deoxygenized state, its red color is less brilliant (like in the case of peripheral venous blood, for example).

Blood removes also the poisons and the products of waste which will be treated by the Foie or the Rein S, which will evacuate them towards outside in the form of Urine.

Composition

Like all conjunctive fabrics, blood consists of three components: the cells and of fundamental substance contrary to other fabrics it is deprived of fibers (collagenous or elastic).

Illustrated elements

  • red Globules or red blood corpuscles or érythrocytes (about 99%). They have neither core nor Organite S, therefore are not cell S themselves. They contain the hemoglobin (1/3 of the components of the Cytoplasme) which makes it possible to fix oxygen but also carbon dioxide or carbon monoxide. Their lifespan is 120 days and their destruction is operated by the Foie, the Rate or osseous marrow.

  • Leucocyte S or white globules (0,2%), which is used in the Immune system to destroy the infectious agents. The leucocytes are a heteroclite whole of cells:
  • Thrombocyte S or blood plates or plates (0,6 - 1,0%), persons in charge of the formation of the plate nail beginning blood coagulation. They are not cells because they do not contain a core, but fragments of Cytoplasme coming from their precursors, the Mégacaryocyte S (giant cells of the osseous Moelle).

These illustrated elements constitutes 45% of whole blood (even Hématocrite), they are all the cells contained in blood. The 55% remainders constitute the Blood plasma, a yellowish liquid which is the liquid phase and is used as suspension for blood.

Blood plasma

The plasma is the liquid component of the blood in which bathe the illustrated elements; however it should well be understood that the illustrated elements do not form part of plasma. It consists of water and various molecules which are thus transported through the organization. It still should be distinguished from the blood serum from which the definition is a little different from that of the blood plasma.

Here principal molecules of plasma:

  • glucose;

  • lipids;
  • the hormones (which can be proteins, modified amino-acids, steroids, or modified lipids of which prostaglandins and thromboxanes);
  • Of the proteins of the complement which have an important role in the initiation of the immunizing response and the ignition;
  • Of proteins of the Coagulation (factors of coagulation).

Fibrillary component

It is represented by the Fibrinogène which in absence of coagulant, polymerizes in Fibrine in a tube after a taking away.

Fundamental substance

It is still called plasma.

Study

Blood can be split between its various components in two ways:

  • Centrifugation in the presence of anticoagulant: one obtains then 2 phases, a yellowish supernatant: plasma and a base of red blood corpuscles. With the interface between these 2 phases, one can observe a ring blanchâtre containing the leucocytes. In this case there, a simple agitation makes it possible to mix all these components and to suspend them.

  • Centrifugation without anticoagulant: a yellowish supernatant then is obtained: serum and a base containing red blood corpuscles imprisoned in a fibrin network. In this case there, the red blood corpuscles cannot be suspended.

Health

A human adult is equipped with approximately 4 to 6 liters of blood. The Hématologie is the medical speciality in charge of the study of the affections of blood circulation:

The body lesions can involve important escapes of blood (Hémorragie S). The thrombocytes are used to coagulate blood in the minor wounds, but the major wounds must be repaired immediately to prevent the exsanguination. Internal wounds can cause serious hemorrhages.

The Hémophilie is a genetic disease. The attack of the process of coagulation appears clinically by hemorrhages.

The important of blood, traumatic losses or not (p.ex. at the time of a surgery), or a blood disease the such Anemia or the Thalassaemia, can require transfusions of blood. Several countries have banks of blood to fill the need for transfused blood. A transfused person must be of a Blood group compatible with that of the donor (transfusion of the same blood group).

Blood is an important vehicle for the infection. A very important example of infection transmitted by blood is the AIDS, whose Virus (HIV) can be transmitted by contact between the blood of a person and blood ou/et the Sperme. For this reason one treats the stained objects of blood like a biological Danger. The infectious mononucleosis is another viral affection of blood.

Blood can also be poisoned by compounds like the carbon monoxide, or the lead which causes the Saturnisme.

The Leucémie is a Cancer blood.

The blood Pressure is important diagnostic tools.

Symbolic system and beliefs

Because of its vital importance, blood has connotations symbolic systems in many religions and of beliefs.

In the Christian religion, the blood poured by the Christ at the time of her crucifixion has a great value symbolic system. According to the catholic and orthodoxe dogma of the Transsubstantiation, the substance of the wine of the Eucharistie is completely changed into the substance of the blood of Christ.

According to the popular beliefs, the Vampire S survive by drinking the blood of the living beings; and blood, human or animal, is still used in a certain number of magic practices.

Blood is an element taboo in a certain number of civilizations; thus, the rites Casher and Halal recommend to eat the meat of animals emptied of their blood.

In the medieval theory of four body moods, blood was associated with fire and a merry and greedy personality ( blood ).

Blood makes it possible in the majority of the cultures to establish an social order. Thus, a person born of noble family during the Early middle ages and of the Rebirth is regarded ipso facto as noble. One will consider also the royal family as having the blue Sang which can give him the divine Droit. That can approach a certain way of the system of caste officially relieved but still sails about it in India. One can then speak about pure and impure blood as in the complete text of the Marseillaise. The purity of blood was also a major topic of the racial theories, the specificity of the race being supposed to be a biological characteristic (and this concept is always used in this direction with regard to the Pets, as in the expression " Thorough-bred " to qualify a Horse race).

In addition to characterizing the identity of a group, blood is consubstantiellement related to that of the individual; also, certain religious groups and Sect S, the such Témoins of Jéhovah go until prohibiting the transfusion of blood, which would be according to them a violation of the divine law.

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