blood

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n.

1. 1. The fluid consisting of plasma, blood cells, and platelets that is circulated by the heart through the vertebrate vascular system, carrying oxygen and nutrients to and waste materials away from all body tissues.
   2. A functionally similar fluid in animals other than vertebrates.
   3. The juice or sap of certain plants.
2. A vital or animating force; lifeblood.
3. One of the four humors of ancient and medieval physiology, identified with the blood found in blood vessels, and thought to cause cheerfulness.
4. Bloodshed; murder.
5. Temperament or disposition: a person of hot blood and fiery temper.
6. 1. Descent from a common ancestor; parental lineage.
   2. Family relationship; kinship.
   3. Descent from noble or royal lineage: a princess of the blood.
   4. Recorded descent from purebred stock.
   5. National or racial ancestry.
7. A dandy.

tr.v., blood·ed, blood·ing, bloods.

1. To give (a hunting dog) its first taste of blood.
2. 1. To subject (troops) to experience under fire: “The measure of an army is not known until it has been blooded” (Tom Clancy).
   2. To initiate by subjecting to an unpleasant or difficult experience.

idioms:

bad blood

1. Long-standing animosity.

in cold blood

1. Deliberately, coldly, and dispassionately.

in (one's) blood

1. So characteristic as to seem inherited or passed down by family tradition.

[Middle English blod, from Old English blōd.]

The fluid that circulates in the blood vessels of the body. Blood consists of plasma and cells floating within it. The cells are derived from extravascular sites and then enter the circulatory system. They frequently leave the blood vessels to enter the extravascular spaces, where some of them may be transformed into connective tissue cells. The fluid part of the blood is in equilibrium with the tissue fluids of the body. The circulating blood carries nutrients and oxygen to the body cells, and is thus an important means of maintaining the homeostasis of the body. It carries hormones from their sites of origin throughout the body, and is thus the transmitter of the chemical integrators of the body. Blood plasma also circulates immune bodies and contains several of the components essential for the formation of blood clots. Finally, blood transports waste products to excretory organs for elimination from the body. Because of its basic composition (cells surrounded by a matrix), development, and ability to modify into other forms of connective tissues, blood can be regarded as a special form of connective tissue. See also Connective tissue.

Formed elements

The cells of the blood include the red blood cells and the white blood cells. In all vertebrates, except nearly all mammals, the red blood cells or corpuscles contain a nucleus and cytoplasm rich in hemoglobin. In nearly all mammals the nucleus has been extruded during the developmental stages.

In normal adult men the blood contains about 5,000,000 red blood corpuscles or erythrocytes per cubic millimeter; in normal adult women, about 4,500,000. Human erythrocytes are about 8 micrometers in diameter and about 2 μm at their thickest and have a biconcave shape. They contain hemoglobin, which imparts to them their color, and possess an envelope. When circulating in the blood vessels, the red blood cells are not evenly dispersed. In the capillaries the erythrocytes are often distorted. In certain conditions they may be densely aggregated. This is known as a sludge. The erythrocytes respond to changes in osmotic pressure of the surrounding fluid by swelling in hypotonic fluids and by shrinking irregularly in hypertonic fluids. Shrunken red blood cells are referred to as crenated cells. The average life of the mature red blood cells is surprisingly long, having a span of about 120 days. See also Hematologic disorders; Hemoglobin.

In humans the white blood cells in the blood are fewer in number. There are about 5000–9000/mm³. In general, there are two varieties, agranular and granular. The agranular cells include the small, medium, and large lymphocytes and the monocytes (see illustration). The small lymphocytes are spherical, about the diameter of erythrocytes or a little larger, and constitute about 20–25% of the white blood cells. The medium and large lymphocytes are relatively scarce. In all lymphocytes the nucleus occupies nearly the whole volume of the cell, and the cytoplasm which surrounds it forms a thin shell. The typical monocyte is commonly as large as a large lymphocyte (12 μm), and constitutes 3–8% of the white blood cells. The nucleus is relatively small, eccentric, and oval or kidney-shaped. The cytoplasm is relatively larger in volume than that in lymphocytes.

Diagrammatic representation of human blood cells.

The granular leukocytes are of three varieties: neutrophil, eosinophil, and basophil. Their structure varies somewhat in different species, and the following applies to those of humans. The neutrophils make up 65–75% of the leukocytes. They are about as large as monocytes with a highly variable nucleus, consisting of three to five lobes joined together by threads of chromatin. The cytoplasm contains numerous minute granules which stain with neutral dyes and eosin. The eosinophils (also called acidophils) are about the same size as the neutrophils but are less numerous, constituting about 1% of the leukocytes. The nucleus commonly contains but two lobes joined by a thin thread of chromatin. The granules which fill the cytoplasm are larger than those of the neutrophils and stain with acid dyes. The basophils are about the same size as the other granular leukocytes. The nucleus may appear elongated or with one or more constrictions. The granules are moderately large, stain with basic dyes, and are water-soluble.

The functions of the leukocytes while they are circulating in the blood are not known. However, when they leave the blood vessels and enter the connective tissue, they constitute an important part of the defense mechanism and of the repair mechanism. Many of the cells are actively phagocytic and engulf debris and bacteria. Lymphocytes are of two major kinds, T cells and B cells. They are involved in the formation of antibodies and in cellular immunity.

The blood platelets are small spindle-shaped or rodlike bodies about 3 μm long and occur in large numbers in circulating blood. In suitably stained specimens they consist of a granular central portion (chromomere) embedded in a homogeneous matrix (hyalomere). They change their shape rapidly on contact with injured vessels or foreign surfaces and take part in clot formation. The platelets are not to be regarded as cells and are thought to be cytoplasmic bits broken off from their cells of origin in bone marrow, the megakaryocytes.

Plasma

Plasma is the residual fluid of blood left after removal of the cellular elements. Serum is the fluid which is obtained after blood has been allowed to clot and the clot has been removed. Serum and plasma differ only in their content of fibrinogen and several minor components which are in large part removed in the clotting process. See also Serum.

The major constituents of plasma and serum are proteins. The total protein concentration of human serum is approximately 7 g/ml, and most other mammals show similar levels. By various methods it can be demonstrated that serum protein is a heterogeneous mixture of a large number of constituents. Only a few are present in higher concentrations, the majority being present in trace amounts. More than 60 protein components have been identified and characterized. Albumin makes up more than one-half of the total plasma proteins and has a molecular weight of 69,000. Because of its relatively small molecular size and its high concentration, albumin contributes to 75–80% of the colloid osmotic pressure of plasma. The immunoglobulins, which represent approximately one-sixth of the total protein, largely constitute the γ-globulin fraction. The immunoglobulins are antibodies circulating in the blood, and therefore are also called humoral antibodies. They are of great importance in the organism's defense against infectious agents, as well as other foreign substances. See also Immunoglobulin.

In addition to the proteins, many other important classes of compounds circulate in the blood plasma. Most of these are smaller molecules which diffuse freely through cell membranes and are, therefore, more similarly distributed throughout all the fluids of the body and not as characteristic for plasma or serum as the proteins. In terms of their concentration and their function, the electrolytes are most important. They are the primary factors in the regulation of the osmotic pressure of plasma, and contribute also to the control of the pH. The chief cations are sodium, potassium, calcium, and magnesium. The chief anions are chloride, bicarbonate, phosphate, sulfate, and organic acids. The circulating blood also contains the many small compounds which are transported to the sites of synthesis of larger molecules in which they are incorporated, or which are shifted as products of metabolic breakdown to the sites of their excretion from the body.

Coagulation

When mammalian blood is shed, it congeals rapidly into a gelatinous clot of enmeshed fibrin threads which trap blood cells and serum. Modern theories envision a succession of reactions leading to the formation of insoluble fibrin from a soluble precursor, fibrinogen (factor I). Blood also clots when it touches glass or other negatively charged surfaces, through reactions described as the intrinsic pathway. Several of the steps in this process are dependent upon the presence in blood of calcium ions and of phospholipids, the latter derived principally from blood platelets. The coagulation of blood can also be induced by certain snake venoms which either promote the formation of thrombin or clot fibrinogen directly, accounting in part for their toxicity.

Platelets, besides furnishing phospholipids for the clotting process, help to stanch the flow of blood from injured blood vessels by accumulating at the point of injury, forming a plug. Platelets participate in the phenomenon of clot retraction, in which the blood clot shrinks, expelling liquid serum. Although the function of retraction is unknown, individuals in whom this process is impaired have a bleeding tendency.

Hereditary deficiencies of the function of each of the protein-clotting factors have been described, notably classic hemophilia and Christmas disease, which are disorders of males and clinically indistinguishable. The various hereditary functional deficiencies are associated with a bleeding tendency with one inexplicable exception. Acquired deficiencies of clotting factors, sometimes of great complexity, are also recognized. Therapy for bleeding due to deficiencies of clotting factors often includes the transfusion of blood plasma or fractions of plasma rich in particular substances the patient may lack. See also Human genetics.

Clinical tests of the coagulability of the blood include (1) determination of the clotting time, that is, the time elapsing until shed blood clots; (2) the prothrombin time, the time elapsing until plasma clots in the presence of tissue thromboplastin (and therefore a measure of the extrinsic pathway of clotting); (3) the partial thromboplastin time, the time elapsing until plasma clots in the presence of crude phospholipid (and therefore a measure of the intrinsic pathway of clotting); (4) the enumeration of platelets; and (5) crude quantification of clot retraction and of the various plasma protein-clotting factors.

Heparin, a polysaccharide–sulfuric acid complex found particularly in the liver and lungs, impairs coagulation; its presence in normal blood is disputed. Both coumarin and heparin are used clinically to impede coagulation in thrombotic states, including thrombophlebitis and coronary heart disease. See also Fibrinogen.

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Blood has always held a great fascination, being regarded as a living substance, the very essence of life. The doctrine of the humours, which dominated Western medical thinking until the Renaissance, held that disease is the consequence of imbalance of the four components of which the human body is composed: blood; phlegm; black bile; and yellow bile. The English physician William Harvey (1578-1637) wrote that ‘blood acts above all the powers of the elements and is endowed with notable values and is also the instrument of the omnipotent creator.’ It is, he believed, ‘the fountain of life and the seat of the soul’.

Blood is of immense cultural significance. We talk of blood ‘being thicker than water’ to signify the strength of family loyalty, as also reflected in ‘blood brothers’. A massacre is a ‘blood bath’, the reward for assassination ‘blood money’. Blood signifies power, for good or evil; the consumption of blood, metaphorically, lies at the heart of the Christian sacrament, yet many societies produce legends of vampires, whose evil is signified by their taste for human blood. Blood is often equated with strength: the monthly loss of blood through menstrual flow frequently led doctors (mostly male) to assume an inherent weakness in women. But too much blood could also be troublesome: ruddy-faced, plethoric men would make an annual visit to the barber-surgeon each spring (blood's season, according to the doctrine of the humours) to be bled. Barbers and surgeons went their separate ways in the seventeenth and eighteenth centuries, but the red stripe down the barber's pole still commemorates this annual blood-letting ritual.

Knowledge of the structure of blood (such as the notion that it consists of cells suspended in a protein-rich fluid called plasma) slowly accumulated from the seventeenth century onwards. The Dutch microscopist Anton van Leeuwenhoek (1632-1723), examining his own blood under a simple microscope, first described the red corpuscles (cells), and measured their diameter. White corpuscles were first observed by the British physician William Hewson (1739-74), who also discovered the essential features of how blood coagulates, showing that it is due to the clotting of plasma rather than changes in the cellular constituents. In the latter half of the nineteenth century it was found that blood cells are the progeny of more primitive cells in the bone marrow. The modern science of haematology stemmed from the work of the German pharmacologist Paul Ehrlich (1854-1915), who developed a stain that led to a clear distinction between the different types of cells in the blood.

An understanding of the function of blood also evolved over several centuries. William Harvey described its circulation in 1628, and a few years later the English physician Richard Lower (1631-91) observed the change from the dark blue colour of venous to the bright red of arterial blood after its passage through the lungs. In 1790 the French chemist Antoine Lavoisier (1743-94) discovered oxygen and found that it was the constituent of air that is responsible for the change of the colour of blood. In the mid nineteenth century it was found that oxygen combines with a substance in the red cells, which was identified as the protein haemoglobin by the German biochemist Felix Hoppe-Seyler (1825-95). By 1900 it was also appreciated that the white cells play a crucial role in defence against infection, an idea first proposed by the Russian zoologist Ilya Metchnikoff (1845-1916).

Blood is the body's major transport system, carrying vital substances to all the tissues and removing their waste products. It delivers oxygen from the lungs and collects carbon dioxide to be excreted there; it takes up nutrients from the gut, and distributes them for use or storage; and by virtue of its passage through the kidneys it provides an important mechanism for the excretion of toxic waste products of metabolism. The blood also distributes hormones from their sites of secretion to their sites of action, and likewise the cells, antibodies, and other substances which combat injury and infection. In performing these functions, the blood continually exchanges substances across the capillary walls with the fluids that bathe all body cells. The total volume of blood, which remains remarkably constant in adults, is approximately 70 ml/kg body weight, or about 5 litres. It consists of a fluid component, plasma, in which are suspended red cells, white cells, and platelets (see figure). In health, the cells comprise about 45% of the total volume of blood: this value is known as the haematocrit, and reflects mainly the bulk of the red blood cells.

Red blood cells

The number of circulating red cells in a unit volume of blood — the red cell count — varies at different stages of development. It is relatively high in fetal life and falls quickly after birth, before gradually rising to reach its adult level by the age of 20 (about 5 million/mm³ of blood). Although it is approximately the same in males and females during childhood, it is higher in males after adolescence. Red cells survive for only about three months in the circulating blood, so production continues throughout life.

The major role of red cells (erythrocytes) is to transfer oxygen from the lungs to the tissues. Their rate of production is beautifully adapted to this function. It is regulated by a hormone called erythropoietin, produced in the kidney in the adult and in the liver in the fetus. Close to the gene that regulates erythropoietin production are regions of DNA that sense oxygen tension; when this falls, erythropoietin synthesis is stimulated, and more red cells are produced in the bone marrow. When adequate oxygenation of the tissues is achieved, erythropoietin production is reduced. By this biological feedback loop the body is able to respond to varying oxygen demands by modifying the rate of red cell production. In addition to erythropoietin, there is probably some fine tuning of the rate of erythropoiesis by other hormones and protein growth factors.

The site of red cell production changes during development. In the embryo, they are made in the yolk sac, in the fetus in the liver and spleen, and in adult life in the bone marrow. These sites all contain a primitive, self-renewing population of blood-cell precursors, the haemopoietic stem cells, which are capable of producing all the different cells of the blood. Red cell production (erythropoiesis) takes about 7 days. The progeny of stem cells destined to become red cells start out as large, nucleated cells; during their development haemoglobin synthesis begins and, after several divisions, their nucleus is condensed and eventually extruded from the cell. This red cell precursor is now called a reticulocyte. Reticulocytes are released from the marrow into the blood; they undergo fine quality control in the spleen, where unwanted nuclear remnants are removed. (This process is different in birds and amphibians; the nucleus is not removed and is retained throughout the life of the red cell in the peripheral blood.) An adequate dietary supply of iron and of specific vitamins is necessary for the synthesis of haemoglobin and the production of normal red cells.

After their release from the bone marrow, red cells spend approximately 120 days in the circulation. During this time they travel over 100 miles, are buffeted at high velocities during their passage through the heart, and have to negotiate tiny capillaries narrower than their own diameter. As they age, subtle structural changes occur which render them identifiable to scavenger cells in the spleen and elsewhere, and they end their days being devoured and digested by these predators.

The red cells of most species are biconcave discs, a shape that offers maximum surface area for exchange of oxygen and carbon dioxide. They consist of a protein and lipid membrane, which encases haemoglobin together with water and a variety of enzymes and salts. Their chemistry is beautifully adapted to their function as an oxygen transporter and to protect them and their haemoglobin from chemical damage.

The oxygen-carrying protein of red cells, haemoglobin, is also closely adapted to its function. In most mammals, adult haemoglobin (haemoglobin A) comprises two unlike pairs of chains of amino acids, or globin chains, called a and b, each of which is folded round one iron-containing haem molecule, to which oxygen can bind. The resulting molecule is designated a₂b₂. In humans, and some other species, there is a different fetal haemoglobin, haemoglobin F, which has a chains combined with g chains (a₂g₂). In most species adult and fetal haemoglobins are preceded by an embryonic haemoglobin. These different haemoglobins are adapted to particular oxygen requirements at different stages of development. While taking up and giving off oxygen, subtle spatial alterations occur between the globin chains which are responsible for the oxygen dissociation properties of haemoglobin, essential for normal oxygen transport. These functions can be modified by carbon dioxide, pH, and intracellular substances such as 2, 3-diphosphoglycerate, the control of which is itself regulated by intracellular pH and oxygen levels. Hence there is an elegant intracellular control network relating oxygen delivery to red cell metabolism which, in turn, reflects the oxygen requirements of the tissues.

White blood cells

The white blood cells, much less abundant than red cells, play a key role in the body's defence against environmental pathogens. They are subdivided — on the basis of their microscopic structure, differences in taking up stains, and functions — into phagocytic (‘eater’) cells (which include neutrophils, monocytes, and eosinophils), and non-phagocytic cells (lymphocytes and basophils).

Phagocytic white cells derive from precursors in the bone marrow. Their production and maturation is controlled by a family of proteins called haemopoietic growth factors. Following their release into the blood, many of them remain in a so-called storage pool, stuck to the wall of blood vessels. The numbers circulating freely in the blood therefore represent just a fraction of the total body content.

The cells of the blood, drawn to scale — red blood cells (RBC), platelets, and the several types of white blood cells


The main function of the neutrophils is to kill microorganisms. They are attracted to areas of damaged tissue, where they internalize bacteria and other foreign particles, killing any invaders by a complex combination of oxidative and non-oxidative mechanisms. Monocytes have similar properties to neutrophils, and play an important role as part of the macrophage (‘big eater’) system by presenting foreign proteins (antigens) to T cells (see below). Eosinophils, which are particularly active against parasitic infections, exert their action by discharging highly active elements from preformed granules. Basophils, and tissue cells called mast cells, to which they are related, also play an important role in combating parasitic infection.

The other important class of white cells is the lymphocytes. These cells play a major role in the body's immune system. They are also derived from haemopoietic stem cells and disseminated in the bloodstream; some migrate to sites known as the ‘primary lympho-epithelial organs’, including the thymus gland, where they differentiate further and eventually populate the ‘secondary lymphoid tissues’, including the spleen, lymphoid tissue in the alimentary canal, and the lymph nodes. One set of lymphocytes, thymus-derived or T cells, migrate to specific areas within these tissues and pass through them into the lymphatic vessels; thus they recirculate from the blood to the lymph, and then back to the blood where the lymphatic system drains into it via the thoracic duct. The Tcells are responsible for cellular immune responses. The other class of lymphocytes, B cells, populate different regions of the lymphatic system. Some of them also recirculate. They are the precursors of antibody-forming cells.

The immune system of a human can differentiate more than one million different foreign proteins, or antigens. T and B cells identify antigen by exposing receptor molecules on their surface: immunoglobulin for B cells, and T cell receptors for T cells. Before their first encounter each lymphocyte can only produce receptors to one particular antigen. When a lymphocyte binds to an antigen, it starts to divide to produce a clone of daughter cells, all with the same specificity — a process known as clonal selection. B cells produce immunoglobulins, or antibodies, in response to particular antigens, while T cells, after being activated by antigen presented to them by macrophages, either kill invading organisms directly, or play more subtle roles in co-ordinating other immune defence mechanisms. The extraordinary specificity and diversity of action of B and T cells is a reflection of a complex series of developmental rearrangements of the genes for immunoglobulins and the T cell receptor.

Platelets and blood clotting

It is vital to have ways to prevent the loss of blood after damage to blood vessels. It is equally important, however, that these processes occur only when they are needed, and do not spread from the site of injury to block off normal healthy vessels. These aims are achieved by the complicated series of cellular and biochemical interactions that constitutes blood clotting. Platelets, the other cellular elements of the blood, play a central role. These small, enucleate cells are produced from large parent cells, the megakaryocytes, in the bone marrow.

When a blood vessel ruptures there is immediate reflex constriction, thus narrowing the opening through which blood can escape. Platelets then aggregate at the site of the disruption. The adhesion of platelets to the exposed tissues beneath the wall of the blood vessel requires the action of a plasma protein called von Willebrand factor, which binds to specific receptors on the outer membrane of the platelet. As platelets adhere they release a variety of chemicals that cause further aggregation, leading to the production of a temporary haemostatic plug.

At the same time as platelets are forming aggregates in the damaged vessel wall, a sequence of reactions — the coagulation ‘cascade’ — is activated. The objective of this complex process is to convert a soluble plasma protein, fibrinogen, to an insoluble fibrin mesh, or blood clot. This conversion requires the action of the enzyme thrombin, which is normally present in the blood in its inactive form, prothrombin. Thrombin also stimulates platelets to release several clotting factors and aggregating agents.

The activation of prothrombin results from the action of a remarkable biological amplification system in which circulating, inactive blood clotting factors are converted to catalytically active forms. The properties, and potential dangers, of this system are phenomenal: a sufficient amount of thrombin can be generated from the prothrombin in 2 ml of blood to clot the entire circulating volume. One of the inactive precursors in the clotting cascade is defective in the blood in haemophilia. Four of the factors require vitamin K for their production in the liver. Ionized calcium is one of the necessary factors.

This system is further complicated by the fact that activation of thrombin can occur through the intrinsic coagulation system, that is by the interaction of circulating factors, as well as by an extrinsic system which requires a factor from the tissues to interact with some of the circulating factors.

There is continual minor damage to the lining of blood vessels, so that blood clotting is continually being activated. Therefore mechanisms must exist for terminating the clotting cascade or dealing with the consequences of its activation. These involve either the inactivation of some of the protein co-factors by the enzymatic action of other plasma proteins (such as protein C or antithrombin III), or the digestion of unwanted fibrin (fibrinolysis) by the enzyme plasmin, activated from the plasminogen which is normally present in the blood.

Haemostasis — the prevention of blood loss — and blood coagulation are thus dynamic processes in which there is continual activation of the complex coagulation pathways, kept in check by inactivation mechanisms together with the removal of unwanted blood clot by the fibrinolytic system.

Plasma

The liquid plasma, in which all the cells of the blood are suspended, contains a variety of substances both in solution and as colloidal particles. There are salts, nutrients from the food (lipids, sugars, and amino acids) and hormones. A complex mixture of proteins includes albumin — the main bulk of the plasma proteins, and of considerable importance in maintaining osmotic homeostasis, as it prevents the accumulation of excess fluid in the body tissues; globulins — some acting as ‘carriers’ for substances such as hormones, and others (gamma-globulins) which are part of the immune system; and also fibrinogen and other substances necessary for clotting.

The main functions of plasma are to transport nutrients, waste materials, and hormones; to provide an appropriate environment for different blood cells; to ensure, by exchange of water and solutes across capillary walls, that the chemical composition of the body fluids, both outside and inside cells, remains within normal, physiological concentrations; and — by carrying the coagulation proteins and their antagonists — to ensure that blood loss is prevented promptly after injury.

— Mark Weatherall, D. J. Weatherall

See also anaemia; blood circulation; blood transfusion; body fluids; haemoglobin; homeostasis; immune system; lymphatic system; menstruation; thymus.

Various blood cells suspended in plasma; carries nutrients and oxygen to tissues, and removes metabolic products. Oxygenated blood travels from the heart in arteries, while deoxygenated blood returns in veins; in the tissues the blood from the arteries enters smaller vessels, the arterioles, then capillaries, which then drain into venules, then the veins. See also blood plasma.

A fluid tissue consisting of red blood cells, white blood cells, and blood platelets (thrombocytes; disc-like structures derived from fragments of bone marrow cells that play an important role in blood clotting) within a liquid matrix called plasma.

An average adult male has about 5 litres of blood. Blood has many functions. It is the main transport medium of the body carrying hormones, nutrients, respiratory gases, and metabolic waste products. It also helps to regulate body temperature by controlling the loss of body heat through the skin. White blood cells and some components of blood plasma play an essential role in the body's defence against disease.

Regular aerobic exercise can significantly change the composition of blood. Exercisers tend to have a higher blood volume, more haemoglobin, more anti-clotting agents, and lower blood cholesterol levels than inactive people.

Over the centuries people like the Mongolian warriors used animal blood as a source of food, often ingesting it fresh. Today, some Masai of Tanzania still follow this practice, ingesting blood for nutrition as they travel with their herds. Elsewhere, blood (primarily from pigs, cows, chickens and geese) is still used as a thickening agent in some dishes, such as blood sausage (also known as black pudding because of the dark color of cooked blood). Blood should never be boiled, or it will clot. A little vinegar keeps blood from clotting during storage. In winemaking, blood is used as a fining agent to help clear suspended particles and clarify the wine. Blood is usually available by special order through some butcher shops.

noun

1. The fluid circulated by the heart through the vascular system: gore. See blood.
2. The crime of murdering someone: homicide, killing, murder. Slang hit. See help/harm/harmless.
3. One's ancestors or their character or one's ancestral derivation: ancestry, birth, bloodline, descent, extraction, family, genealogy, line, lineage, origin, parentage, pedigree, seed, stock. See kin, precede/follow.
4. Noble rank or status by birth: birth, blue blood, nobility, noblesse. See kin, over/under.

Idioms beginning with blood:
blood is thicker than water

In addition to the idiom beginning with blood, also see bad blood; draw blood; flesh and blood; in cold blood; in one's blood; make one's blood boil; make one's blood run cold; new blood; out for (blood); run in the blood (family); scream bloody murder; shed blood; sporting blood; sweat blood. Also see under bleed.

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n

The fluid circulating through the heart, arteries, capillaries, and veins; carries nutrients and oxygen to body tissues.

For more information on blood, visit Britannica.com.

(Heb. dam). The vital fluid which, in biblical thought, is the seat of life itself, "for the life of the flesh is in the blood" (Lev. 17:11; cf. Deut. 12:23). This explains the repeated prohibition against consuming the blood of animals or birds (e.g., Lev. 3:17, 7:26, 17:13; Deut. 12:23-25), a law peculiar to Israel in the ancient world. On the basis of Gen. 9:4, this same prohibition was included among the seven Noachide Laws devolving upon all mankind and the penalty for infringing it was Karet, Divine punishment or "excision" (Lev. 7:27, 17:10-14). The blood of any sacrifice had to be poured out, dashed against the altar (Ex. 24:6, 29:21; Lev. 1:5), and in some instances either poured over the horns of the altar or at its base (Lev. 4:7). The last procedure was followed in the case of a guilt offering brought by a priest (Lev. 4:3-7). That priestly sacrifice was one that involved the sprinking of the blood seven times in front of the Sanctuary's curtain. At the investiture of Aaron and his sons, Moses took some of the consecrated animal's blood from the altar and dabbed it on the lobe of Aaron's right ear, on the thumb of his right hand, and on the big toe of his right foot, then did the same to Aaron's sons (Lev. 8:23-24). The blood of a slaughtered bird was likewise used in purification rites, e.g., that of a leper (Lev. 14:4-7). Non-Israelites were also subject to the general law when resident in the Land of Israel, the blood of any animal or fowl having to be poured out and covered with dust (Lev. 17:12-13; Deut. 12:16, 23-24).

Among the pagan Canaanites, blood was conceived as the food of the gods and as a potent magical element. It is in protest against the former concept that the psalmist voices God's declaration: "Do I eat the flesh of bulls, or drink the blood of he-goats?" (Ps. 50:13; cf. 16:4). This concept is elsewhere reflected in the wild behavior of Elijah's opponents, the prophets of Baal, who gashed themselves with knives and spears until they were covered with blood (I Kings 18:28), a practice expressly forbidden by the Torah (Deut. 14:1).

In biblical sources, "blood" is often used as a metonym for Murder. Thus, Abel's blood "cries out from the ground" (Gen. 4:10), homicides are "men of blood" (Ps. 5:7, 26:9, 59:3, etc.), and the criminal's blood "will be upon him" (Lev. 20:9 ff.; Josh. 2:19; Ezek. 18:13). Murdering a guiltless person is called "shedding innocent blood" (II Kings 24:4; Isa. 59:7; Jer. 22:17; Joel 4:19; Prov. 6:17), but God will surely avenge "the blood of His servants" (Deut. 32:43; Ps. 79:10). Blood is also the bond of solidarity uniting a man with his family or tribe, one that gave rise to the practice of avenging a slain kinsman (see Blood Avenger). Unlike the pagan legal systems of antiquity, biblical law does not permit the acceptance of financial compensation for the deliberate taking of a human life (Num. 35:31-34). The shedding of innocent blood "defiles the land" and can only be expiated through the death of the murderer, in keeping with the injunction that "whoever sheds the blood of man, by man shall his blood be shed" (Gen. 9:6). Hence the ceremony of expiation for a murder committed by a person or persons unknown (Deut. 21:1-9), which concludes with the elders of the nearest town washing their hands in token of their innocence. To be finally absolved of bloodguilt, they make the following declaration: "Our hands did not shed this blood, nor did out eyes see it done. Absolve, O Lord, Your people Israel whom You redeemed, and do not let guilt for the blood of the innocent remain among Your people Israel."

Although some of these detailed regulations lapsed with the Temple's destruction, others (of biblical origin, but interpreted and codified by the sages) remain in force and have exerted a major impact on traditional Jewish life. One example is the rite of Circumcision, which involves a slight loss of blood, the child undergoing this operation being termed in the Bible ḥatan damim, "a bridegroom of blood" (Ex. 4:25-26). Even in the case of a child born circumcised, or of a proselyte to Judaism who has already been circumcised for health reasons, the officiating mohel allows a symbolic drop of blood to flow. The laws of Family Purity (based on Lev. 15:19 ff.) declare a woman ritually "unclean" and prohibit normal marital relations during the period of her menstrual flow (or any other discharge of blood from the womb) and for at least a week thereafter (see also Niddah).

A direct consequence of the biblical prohibitions concerning blood may be seen in kashrut---the Jewish Dietary Laws. Apart from stipulating which domestic beasts and fowl are permitted, these laws authorize only Sheḥitah as the method of slaughter, whereby pain is reduced to a minimum through the swift draining of lifeblood. Any residual blood is then drawn out by a process of soaking and salting, after which the Kasher meat may be prepared for Jewish consumption. The animal's lifeblood must be covered with sand or earth at the time of slaughter, unless it is collected for use as fertilizer; and the dietary laws even prohibit the eating of an egg in which a blood spot is attached to the yolk.Strict adherence to these regulations made even the thought of drinking blood abhorrent to the Jew. Pagan charges concerning the eucharist embarrassed the early Christians, who found themselves accused of consuming human flesh and blood. By a grim irony, such baseless accusations were later directed against the Jews of medieval Europe. Malicious preachers, ignorant rabble-rousers, and vindictive Jewish apostates exploited popular fear and superstition, alleging that the blood of a Christian child was an essential ingredient in certain Jewish rites. Furthermore, the periodic coincidence of Easter with Passover led to "ritual murder" charges that pursued Jews down the ages. It was thus alleged that Christian blood was used in the preparation of unleavened bread and wine for the Passover Seder. Despite the efforts made by popes, emperors, and enlightened scholars to refute these lies, agitators down to the 20th century utilized the disappearance or unsolved murder of a Christian child for the propagation of miracle tales, the torture, execution, or wholesale massacre of innocent Jews, and the confiscation of their property.

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In many respects, ancient Israel's attitude towards blood both as sacred and purifying (e.g., with respect to the Day of Atonement ritual), and as a major sign of ritual impurity (e.g., with respect to the monthly menstrual flow) was unique among the peoples of the ancient Near East. The Israelite conception of the sanctity of blood is expressed by the prohibition of its consumption, which occurs in the Bible in three forms: (a) the prohibition of blood consumption together with the positive ritual requirements of sprinkling upon the altar the blood of all slaughtered animals potentially valid for sacrifice (Lev 17:3-12; cf Lev 1:5; Is 1:11) and the covering up with dust of the blood of all game animals which are invalid for sacrifice (Lev 17:13-14); (b) the prohibition of blood consumption together with the specific deuteronomic pronouncement that the blood of all animals slaughtered for non-sacrificial purposes should be poured out on the ground "like water" (Deut 12:16, 23; 15:23); (c) the prohibition "to eat upon or over blood" (Lev 19:26; I Sam 14:32-34; Ezek 33:25), a possible reference to pagan divination customs in which the blood absorbed by the earth is intended to satisfy thirsty deities or demons residing in the netherworld. The deities in return would reveal the future. The most persuasive evidence for this view is the context of Leviticus 19:26, which includes two other prohibitions against pagan divination customs. On the other hand, the idiom could also be translated "to eat together with the blood" giving a meaning similar to formulations 1 and 2 above. The eating of blood is forbidden because it is identified with life (Gen 9:4; Lev 17:10ff). The empirical observation concerning the association between blood and the lifeforce (Gen 9:4; Deut 12:23) was in all likelihood a result of the high visibility of blood from both the wounds of the living and the bodies of slain corpses from which it drained. Here also belongs the ritual impurity of the monthly menstrual flow (Lev 15:19, 25). The "spilling/shedding of blood" is a common phrase in the Bible; and the avenger of "spilt innocent blood" is called "the avenger of blood" (Num 35:27; Deut 19:6, 12; Josh 20:9; II Sam 14:11).

"Blood" appears together with "fat" as the two principal components of an animal, which must be offered to God when the animal is sacrificed (Num 18:17). The priestly techniques of offering the blood upon the altar were rendered in the following expressions: "sprinkle the blood all around on the altar" (Lev 3:2, 8, 13; II Chr 29:22); "drained out at the side of the altar" (Lev 1:15); "put it on the horns of the altar with your finger" (Ex 29:12; Lev 4:7, 18, 25, 30, 34), "drained out/poured out (at the base of the altar)" (Lev 5:9; 8:15; Deut 12:27). The fine distinctions between these four techniques are unknown today.

Blood-manipulation is most intensified in the Day of Atonement ritual (Lev chap. 16). Expiation is made by Aaron, the high priest, for the Shrine and the Tent of Meeting, by taking some of the blood of a slaughtered bull (on behalf of the priesthood) and that of a slaughtered he-goat (on behalf of all the Israelites) and sprinkling it seven times with his finger over the cover of the ark and in front of it. Then Aaron makes expiation for the altar by taking some of the remaining blood of the same two slaughtered animals (again on behalf of the priesthood and all Israelites respectively) and applying it to each of the four horns of the altar, and by taking the rest of the blood and sprinkling it with his finger seven times on the altar itself (Lev 16:14-19).

The use of the blood for expiation in Israelite ritual is quite intentional as is emphasized by Leviticus 17: 11 and was also apotropaic. The blood of the Passover offering, which was smeared on the door posts of the homes of the Hebrews in Egypt during the eve of the first Passover, was intended to serve as a sign of Divine protection (see especially Ex 12:7, 13, 21-23).

The NT follows Judaism in using the term blood as equivalent to life or humanity. Thus the expression "flesh and blood" (Matt 16:17) means humanity and is generally used in contrast to Divine power and wisdom as in Galatians 1:16.

The term takes on special significance in the designation: "the blood of Christ" where it denotes his sacrificial death. Fundamental is the pauline affirmation that now, independent of the law, God's way of righting wrong has been brought to light. It is effective in Christ through faith, now all are justified by God's free grace alone, through his act of liberation in the person of Christ Jesus "whom God set forth to be a propitiation by his blood, through faith" (Rom 3:25).

For the writer of Hebrews (chap. 9) the superiority of the new covenant consists in the fact that Jesus as high priest sacrificed his own blood (life) (Heb 9:12). Although reference is made to the blood of goats and calves he argues that if that was effective, how much more so is the blood of Christ effective to "purge your conscience from dead works to serve the living God?" (Heb 9:14). The Epistle to the Hebrew seeks to show that Christians have no inferior faith and that the blood of the new covenant is firmly related to the old covenant. Yet the new covenant provides a freedom of speech or boldness to enter the sanctuary and it is the blood of Jesus which provides this freedom (Heb 10:19-20). In this way the writer stresses the power of the death of Christ for the believer. One of the most serious things a Christian can do is to profane the blood of the covenant by trampling under foot the Son of God (Heb 10:29). Above all he is convinced that the sprinkled blood of Jesus "speaks better things than that of Abel" (Heb 12:24).

The Council of Jerusalem in the year 50 placed certain restrictions on the Gentile Christians and one of them was to "abstain from � blood" (Acts 15:20) out of respect for the Jews.

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The Roman commentator Lucan (1st cent. AD) reported blood staining the trees of a Celtic sacred grove near Marseilles. Badb, Mórrígan, and Macha send frogs, streams of blood, and rains of fire to help defeat the Fir Bolg at Mag Tuired. After Cúchulainn has drunk some of Emer's blood while extracting a sling stone from her, he is forbidden to marry her. After Cúchulainn has killed Eochaid Glas, the hero sees a banshee whom Eochaid had outraged bathe in his blood to wash away the shame. The blood of three kings is needed to ransom Fionn mac Cumhaill.

Connective tissue consisting of red blood corpuscles, white blood cells, and blood platelets in a liquid matrix called the plasma. Blood is the main transport medium in the body. See also lymph.

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, CORRUPTION OF THE see corruption of blood.

The fluid circulating through the heart, arteries, veins, and capillaries of the circulatory system. Blood carries oxygen and nutrients to the cells of the body and removes waste materials and carbon dioxide. It is composed of plasma (mainly water, but with a mixture of hormones, nutrients, gases, antibodies, and wastes), red blood cells (which carry oxygen), white blood cells (which help combat infection), and platelets (which help the blood clot).

The red fluid that circulates through the heart, arteries, capillaries and veins carrying nutrients and oxygen to the body tissues and metabolites away from them. It consists of a yellow, protein-rich fluid, the plasma, and the cellular elements including leukocytes, erythrocytes and platelets. It has a high viscosity and osmotic tension and clots on exposure to air and to damaged tissue. It has an essential role in the maintenance of fluid balance.
In an emergency, blood cells and antibodies carried in the blood are brought to a point of infection, or blood-clotting substances are carried to a break in a blood vessel. The blood carries hormones from the endocrine glands to the organs they influence. And it helps in the regulation of body temperature by carrying excess heat from the interior of the body to the surface layers of the skin, where the heat is dissipated to the surrounding air. See also bloody.

• arterial b. — oxygenated blood in the arterial side of the circulation between the cardiac ventricles and the capillaries.
• b. buffers — substances which enable the blood to absorb much acidity without significant change in pH. The principal ones are the bicarbonate and hemoglobin buffers.
• central b. — blood from the pulmonary venous system; sometimes applied to splanchnic blood, or blood obtained from chambers of the heart or from bone marrow.
• central venous b. — unoxygenated blood collected centrally from the right atrium or venae cavae.
• citrated b. — blood treated with sodium citrate to prevent its coagulation.
• b. clotting cascade — see coagulation cascade.
• cord b. — that contained in the umbilical vessels at the time of delivery of the fetus.
• defibrinated b. — whole blood from which fibrin has been separated during the clotting process.
• extracorporeal b. flow — see extracorporeal circulation.
• b. in feces — see melena.
• b. islet — aggregates of splanchnic mesoderm on the surface of the yolk sac and allantois; the first blood cells in the embryo.
• b. lactate — this estimation has good predictive value in a number of diseases, e.g. intestinal obstruction in horses.
• b. in milk — appears as clots or as diffuse red tint. Common only in recently calved cows or after trauma. Of no disease significance but renders the milk unsuitable for sale.

  Blood clots in pink milk. By permission from Blowey RW, Weaver AD, Diseases and Disorders of Cattle, Mosby, 1997

• occult b. — that present in such small amounts as to be detectable only by chemical tests or by spectroscopic or microscopic examination. See also occult blood test.
• b. osmolality — see serum osmolality.
• peripheral b. — that obtained from the circulation remote from the heart; the blood in the systemic circulation.
• selective b. agar — see blood agar.
• shunted b. — blood which is not oxygenated in the lung because it passes through unaerated tissue.
• sludged b. — blood in which the red cells have become aggregated into clumps and is most marked where the flow rate is slowest, i.e. in the capillaries.
• b. solutes — see individual elements, metabolic products, hormones and the like.
• stiff b. agar — see blood agar.
• b. substitutes — synthetic substances that may be used in place of blood or its components include dextran, hydroxyethyl starch, polyvinylpyrrolidone, gelatin and perfluorocarbon.
• b. urea nitrogen (BUN) — see urea nitrogen.
• b. urea test — see urea nitrogen.
• b. in urine — see hematuria.
• venous b. — blood which has passed through the capillaries and discharged its oxygen load to tissues and relieved the tissue load of carbon dioxide by absorbing it, and is on its way to the lungs to reverse these processes; is dark red in color due to the high concentration of reduced hemoglobin.
• b. volume expanders — are used in the treatment of shock to restore tissue perfusion. Various fluids including whole blood, plasma, crystalloids and colloids may be used.
• b. in vomitus — see hematemesis.
• whole b. — that from which none of the elements has been removed, especially that drawn from a selected donor under aseptic conditions, containing citrate ion or heparin, and used as a blood replenisher.

IN BRIEF: A red fluid in the body that is pumped by the heart through veins, arteries, and capillaries to carry food and oxygen and take waste products. A family relationship.

Blood donated to blood banks helps save lives.

Quotes:

"Peace, above all things, is to be desired, but blood must sometimes be spilled to obtain it on equable and lasting terms." - Andrew Jackson

"The future can be anything we want it to be, providing we have the faith and that we realize that peace, no less than war, required blood and sweat and tears." - Charles F. Kettering

"Young blood must have its course, lad, and every dog its day." - Charles Kingsley

"No one need think that the world can be ruled without blood. The civil sword shall and must be red and bloody." - Martin Luther

"Blood will tell, but often it tells too much." - Don Marquis

"Blood alone moves the wheels of history." - Benito Mussolini

See more famous quotes about Blood

Nothing has so defined the vampire as its relationship to blood. The vampire was essentially a bloodsucker, a creature who lived off of the blood of humans. Quite early in his visit to Castle Dracula, Jonathan Harker was lectured by his host on the general importance of blood. He noted that the Szekelys, "we of the Dracula blood," helped to throw off the despised Hungarian yoke. He further noted, in a line which soon would take on a double meaning, "Blood is too precious a thing in these days of dishonorable peace ..." (chapter 3). As Harker tried to understand his desperate situation, he noted that Dracula had bad breath with "a bitter offensiveness, as one smells in blood." He discovered the secret when he found Dracula asleep with his mouth redder than ever and "on the lips were gouts of fresh blood, which trickled from the corners of the mouth and ran over the chin and neck .... It seemed as if the whole awful creature were simply gorged with blood; he lay like a filthy leech, exhausted with his repletion." Harker lamented his role in freeing Dracula on London.

The Significance of Blood: Since ancient times, humans have seen the connection between blood and life. Women made the connection between birth and their menstrual flow. Hunters observed the relationship between the spilling of blood and the subsequent loss of consciousness, the ceasing of breath, and eventual death of the animals they sought. And if an animal died of some cause with no outward wound, when cut, the blood often did not flow. Blood was identified with life, and thinkers through the ages produced endless speculations about that connection. People assigned various sacred and magical qualities to blood and used it in a variety of rituals. People drank it, rubbed it on their bodies, and manipulated it in ceremonies.

Some believed that by drinking the blood of a victim the conqueror absorbed the additional strength of the conquered. By drinking the blood of an animal one took on its qualities. As late as the seventeenth century, the women of the Yorkshire area of England were reported to believe that by drinking the blood of their enemies they could increase their fecundity.

Among blood's more noticeable qualities was its red color as it flowed out of the body, and as a result redness came to be seen as an essential characteristic of blood, the vehicle of its power. Red objects were often endowed with the same potency as blood. In particular, red wine was identified with blood, and in ancient Greece , for example, red wine was drunk by the devotees of the god Dionysus in a symbolic ritual drinking of his blood.

Blood was (and continues to be) seen as somehow related to the qualities possessed by an individual, and beliefs carried references to admirable people as having "good" blood or evil persons as possessing "bad" blood. The blood of the mother was passed to the child, and with it the virtues and defects of the parents were passed to any offspring. Thus blood, in a somewhat literal sense, carried the essential characteristics of the larger collectives-families, clans , national/ethnic groups, even whole races. Such beliefs underlie the modern myth which permitted the Nazi purge of Jews and other supposed lesser races and the practices in American blood banks until recent decades to separate "negro" blood from that of "white" people.

To a lesser extent, blood was identified with other body fluids, most notably semen. In the process of creating a baby, men do not supply blood, only their seed. Thus it was through the semen that male characteristics were passed to the child. In the mythology of race, each of the body fluids-semen, the blood that flowed when the hymen was broken, and menstrual blood-were associated together as part of the sexual life and ascribed magical properties. This association was quite explicit in the sexual teaching of modern ritual magic.

Blood in the Biblical Tradition: The ancient Jewish leaders made the same identification of blood and life. In the biblical book of Genesis, God tells Noah,

But you must not eat the flesh with the life, which is the blood, still in it. And further, for your life-blood I will demand satisfaction; from every animal will I require it, and from a man also will require satisfaction for the death of his fellow-man.

He that shed the blood of a man, for that man his blood shall be shed; for in the image of God has God made man.

Israel instituted a system of blood sacrifice in which animal blood was shed as an offering to God for the sins of the people. The book of Leviticus included detailed rules for such offerings with special attention given to the proper priestly actions to be taken with the blood. The very first chapter stated the simple rules for offering a bull. It was to be slaughtered before the Tent of the Presence, and the priest was to present the blood and then fling it against the altar. The mysterious sacredness of the blood was emphasized in that God reserved it to himself. The remaining blood was spilled before the altar, and strictures were announced against the people eating the blood. "Every person who eats the blood shall be cut off from his father's kin" (Lev.7:27).

Special rules were also established for women concerning their menstrual flow and the flow of blood that accompanied childbirth. Both made a woman ritually impure, and purification rituals had to be performed before she could again enter a sanctuary. In like measure, the discharge of semen caused a man to be ritually impure.

The most stringent rules concerning blood were in that section of Leviticus called the Holiness Code, a special set of rules stressing the role of the people, as opposed to the priest, in being holy before God. Very early in the code, the people are told:

If any Israelite or alien settled in Israel eats blood, I will see my face against the eater; and cut him off from his people, because the life of a creature is the blood, and I appoint it to make expiation on the altar for yourselves; for the blood is the life that makes expiation. Therefore I have told the Israelites that neither you, nor any alien settled among you, shall eat blood.

Indeed, "For the blood is the life" has been the most quoted Biblical phrase in the vampire literature.

Christianity took Jewish belief and practice to its extreme and logical conclusion. Following his death and (as Christians believe) his resurrection, Jesus, its founder, was worshiped as an incarnation of God who died at the hands of Roman executioners. Christians depicted his death as a human sacrifice, analogous, yet far more powerful, than the Jewish animal sacrifices. As the accounts of his last days were assembled Jesus instituted the Lord's Supper during which he took a cup of wine and told his disciples, "Drink from it, all of you. For this is my blood, the blood of the covenant, shed for many for the forgiveness of sins" (Matthew 26: 27). Following his sentencing of Jesus, the Roman governor Pilate washed his hands and told the crowd who had demanded Jesus' death, "My hands are clean of this man's blood." The crowd replied, "His blood be upon us, and on our children" (Matthew 27:24-26). As he hung on the cross, a soldier pierced his side with a lance, and his blood flowed from the wound.

Early Christian thought on the significance of Christ's death was clearly presented in the Apocalypse (The Book of Revelation) in which John spoke of Jesus as the one who "freed us from our sins with his life's blood" (Revelation 1:5). He admonished those suffering persecution by picturing their glory in heaven as the martyrs for the faith. They wore a white robe which had been washed in the blood of the Lamb.

In Christian lands, to the common wisdom concerning life and blood, theological reflection added a special importance to blood. The blood of Christ, in the form of the red wine of the Eucharist, became the most sacred of objects. So holy had the wine become that during the Middle Ages a great controversy arose over allowing the laity to have the cup. Because of possible carelessness with the wine, the Roman Catholic Church denied the cup, a practice which added more fuel to the fire of the Protestant Reformation of the sixteenth century.

In the light of the special sacredness of Christ's blood, the vampire, at least in its European appearances, took on added significance. The vampire drank blood in direct defiance of the biblical command. It defiled the holy and stole that which was reserved for God alone.

The Vampire and Hematology: The vampire myth arose, of course, prior to modern medicine. It has been of some interest that Dracula was written just as modern medicine was emerging, and Bram Stoker mixed traditional lore about blood with the new medicine. Lucy Westenra, even as she anticipated her marriage to Arthur Holmwood, lay hovering near death. Reacting quickly, Abraham Van Helsing gathered Holmwood and Lucy's two other suitors, Quincey P. Morris and Dr John Seward , to apply a wholly unique scientific remedy to the vampire's attack. He had diagnosed a loss of blood, and now Van Helsing ordered a transfusion, at the time a new medical option. He and each of Lucy's suitors in turn gave her their blood. Following her death, Holmwood, in his grief and disappointment, made the observation that in the giving of blood he had in fact married Lucy and that in the sight of God they were husband and wife. Van Helsing, assuming his scientific role, countered his idea by suggesting that such an observation would make Lucy a polyandrist and the previously married Van Helsing a bigamist.

The idea of using a transfusion to counter the vampire introduced a new concern into the developing myth of the vampire through the twentieth century, especially as the supernatural elements of the myth were being discarded. If vampirism was not a supernatural state, and rather was caused ultimately by a moral or theological flaw of the original vampires, then possibly the blood thirst was the symptom of a diseased condition, caused by a germ or a chemical disorder of the blood, either of which might be passed by the vampire's bite. In the mid-1960s there was brief, yet serious, medical speculation that vampirism was the result of misdiagnosed porphyria, a disease that causes its victims to be sensitive to sunlight and which could be cured or helped.

Anemia is a disease of the blood that was initially associated with vampirism. Anemia is caused by a reduction of either red blood cells or hemoglobin (the oxygen-carrying pigment of the cells) relative to the other ingredients in the blood. The symptoms include a pale complexion, fatigue, and in its more extreme instances, fainting spells. All are symptoms usually associated with a vampire attack. In Bram Stoker's novel, Dracula, during the early stages of Lucy Westenra's illness, Dr. John Seward hypothesized that possibly she was suffering from anemia. He later concluded that she was not suffering from the loss of red blood cells, but from the loss of whole blood. Dr. Abraham Van Helsing agreed with his friend, "I have made careful examination, but there is no functional cause. With you I agree that there has been much blood lost; it has been, but is not. But the conditions of her are in no way anaemic" (chapter 9). While Stoker dismissed any association of anemia and vampirism, over the succeeding decades, attempts to posit anemia as the underlying explanation of vampirism occasionally emerged.

The Literary Tradition: Increasingly through the century, as knowledge of the minute details concerning the function and makeup of human blood were explored by research specialists, novelists and screenwriters toyed with the idea of vampirism as a disease. During the last years of the pulp fiction era, writers such as Robert Bloch, George Whitley, David H. Keller, and William Tenn suggested the diseased origin of vampirism in a series of short stories. For example, in William Tenn's 1956 short story "She Only Goes Out at Night," Tom Judd, the son of a village doctor, falls in love with a strange woman. Tom's father coincidentally discovered an epidemic in town whose victims were all anemic. The woman, who had just moved to town, was a Romanian by descent and only came out at night. Putting the sudden wave of anemia together with the behavior patterns of the woman, the wise old doctor suggested she was a vampire. As he explained it, the vampire condition was passed from parent to child, though usually only one child in each generation developed it. His son still wanted to marry the woman. He responded with a medical observation, "Vampirism may have been an incurable disease in the fifteenth century, but I am sure it can be handled in the twentieth." Her symptoms suggested she had an allergy to the sun, for which he prescribed sunglasses and hormone injections. He then dealt with her blood thirst by supplying her with dehydrated crystalline blood which she mixed with water and drank once a day. The vampire and Tom lived happily ever after.

Vampirism as disease came powerfully to the fore in the late 1960s television series Dark Shadows. Dr. Julia Hoffman was introduced into the show to treat the problems of Maggie Evans, one of the show's main characters. A short time after her initial appearance, she met Barnabas Collins and discovered that he was a vampire. Rather than seek to destroy him, however, she devised a plan to assist him in a cure of his vampiric condition. Collins soon grew impatient and demanded that the process be speeded up. His body did not react favorably to the increased dosages of Hoffman's medicines, and he reverted to his true age-200 years old. He was able to revive his youth by biting a young woman, and he then turned on Hoffman. Hoffman was able to thwart his efforts by threatening him with her research book, which contained all the details of her treatments and revealed Collins's true nature. Before Barnabas could locate the book, he and the storyline were transported into the past, to 1795.

Shortly after his return to the present (1968), Collins was in a car accident. Hospitalized, he received a transfusion that temporarily cured him. He was a human and for the first time in 200 years was able to walk in the sunlight. He was, however, returned to his vampiric state by the bite of his former love, Angelique Bouchard, who had died and returned as a vampire.

A character similar to Hoffman also appeared in the recent television series, Forever Knight.Nicolas Knight, the show's vampire, was a policeman on the Toronto police force. His friend and confidante was Dr. Natalie Lambert, a forensic pathologist. Throughout the series, she sought a means to transform Knight into a human, but with negative results to date.

In the decades since World War II, novelists have also explored the idea that a diseased condition produced vampirism. Simon Raven's Doctors Wear Scarlet (1960), for example, described vampirism as a form of "sado-sexual perversion." The story sent the hero, Richard Fountain, to Greece to escape an oppressive personal situation in England. In Greece he met a beautiful vampiress who slowly drained his blood. He was rescued before he was killed and returned safe to his British home.

Jan Jennings' Vampyr (1981) brought a research scientist into a relationship with Valan Anderwalt, a vampiress. The scientist, in love with Valan, tried to find the causes of her state. He traced vampirism to ancient China and found it to be a contagious physical condition which had been brought to America by the early Dutch colonists. Unfortunately, he was not able to make any progress in curing her.

That same year Whitley Strieber introduced an interesting triangle relationship in The Hunger. Miriam Blaylock was an immortal alien vampire. She was on earth and could transform humans into vampires. Such human vampires, however, were not immortal and began to age and disintegrate after several centuries passed. Not wishing to lose another companion, Blaylock sought out the services of an expert in longevity, Sarah Roberts, in the hopes that she would be able to save John, her present male companion. Unfortunately, no solution presented itself before John succumbed to his deteriorating condition.

Most recently, Dan Simmons sent his leading character, Kate Neuman, a hematologist, into post-revolutionary Romania in Children of the Night. The book began with her using her knowledge of rare blood diseases to treat people in Bucharest. While there, she fell in love with a seven-month-old boy, Joshua, presumably an orphan. He was unique in that he required biweekly transfusions to stay alive. He also had unusual blood which, she came to believe, held the clue to cures for AIDS, cancer, and other blood diseases. She arranged his adoption and brought him home with her to Colorado. Soon after, the boy was kidnapped and returned to Romania. In the exciting climax of the story, she was forced to return to Romania and to face the boy's father, Vlad the Impaler, the real Dracula. Dracula was dying, and his son, Joshua, was to become the leader of the family in his place.

Conclusion: The traditional beliefs that surrounded blood, the medical exploration of its properties, and the analogies it harbored to life itself, facilitated the adaptability of the vampire myth to a seemingly endless number of situations. Such adaptability has provided an understanding of why the vampire myth has stayed alive and has so many devotees to this day. Scientific considerations of the vital function played by blood in the human body have, if anything, given it an even more mystical place in human life and promoted its resacralization in this post-secular society.

Cox, Greg. The Transylvanian Library: A Consumer's Guide to Vampire Fiction. San Bernadino, CA: Borgo Press, 1993.
Scott, Kathryn Leigh, ed. The Dark Shadows Companion: 25th Anniversary Collection. Los Angeles: Pomegranate Press, 1990. Simmons, Dan. Children of the Night. New York: G. P. Putnam's Sons, 1992.
Strieber, Whitley. The Hunger. New York: William Morrow, 1981.
Teem, William. "She Only Goes Out at Night." Fantastic Universe 6, 3 (October 1956). Reprinted in Weird Vampire Tales. Ed. by Robert Weinberg, Stefan R. Dziemianowicz, and Martin H. Greenberg. New York: Gramercy Press, 1992.

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Dansk (Danish)
n. - blodsudgydelse
v. tr. - give blod på tanden

idioms:

• blood bank    blodbank
• blood brother    blodbroder
• blood count    blodtælling
• blood feud    blodfejde, vendetta
• blood group    blodtype, blodgruppe
• blood heat    legemstemperatur
• blood lust    blodtørst, blodrus
• blood money    blodpenge
• blood poisoning    blodforgiftning
• blood pressure    blodtryk
• blood relation    blodsbeslægtet, kødelig slægtning
• blood sport    jagt, rævejagt
• blood ties    blodets bånd
• blood transfusion    blodtransfusion
• blood type    blodtype, blodgruppe
• blood vessel    blodkar, blodåre
• make someone's blood boil    få nogens blod til at koge

n. - blod

Nederlands (Dutch)
bloed, het bloedvergieten, temperament, afstamming, familie, modieus man, bebloeden, ontgroenen, jachthond bloed laten ruiken

Français (French)
n. - (Biol, Physiol) sang, sang (royal, etc), (fig) mort, (fig) colère, rage, sang neuf, (US) frère, (fig) peau, petit-maître (arch)
v. tr. - (fig) donner le baptême du feu à, acharner, (Chasse) donner le goût du sang à, initier (un chasseur débutant) (en l'aspergeant du sang de la bête morte)

idioms:

• blood bank    (Méd) banque du sang
• blood brother    (US) frère
• blood count    (Méd) numération globulaire
• blood feud    vendetta
• blood group    (Méd) groupe sanguin
• blood heat    température du sang
• blood lust    (être) assoiffé de sang
• blood money    prix du sang, argent versé pour un meurtre
• blood poisoning    empoisonnement du sang, septicémie
• blood pressure    tension artérielle
• blood relation    (être) un parent par le sang
• blood sport    sport sanguinaire
• blood ties    liens du sang
• blood transfusion    transfusion sanguine
• blood type    (Méd) groupe sanguin
• blood vessel    vaisseau sanguin
• make someone's blood boil    faire enrager, faire bouillir le sang de qn

n. - (US) membre d'une tribu indienne d'Amérique du Nord et de la confédération de trois tribus indiennes (Blackfoot)

Deutsch (German)
n. - Blut
v. - an Blut gewöhnen

idioms:

• blood bank    Blutbank
• blood brother    leiblicher Bruder, Blutsbruder
• blood count    Blutbild, Blutkörperchenzählung
• blood feud    Blutrache
• blood group    Blutgruppe
• blood heat    Körpertemperatur
• blood lust    Blutgier
• blood money    Blutgeld
• blood poisoning    Blutvergiftung
• blood pressure    Blutdruck
• blood relation    Blutsverwandter
• blood sport    Sport, der Tiere verwundet oder tötet, Hetzjagd
• blood ties    Bande des Blutes
• blood transfusion    Bluttransfusion
• blood type    Blutgruppe
• blood vessel    Blutgefäß, Blutbahn
• make someone's blood boil    in Rage bringen, jmdn. rasend machen, jmdn. in Wut bringen

n. - Nordamerikanischer Indianer

Ελληνική (Greek)
n. - αίμα, συγγένεια, καταγωγή
v. - βαπτίζω με αίμα θηράματος, μυώ στα μυστικά του κυνηγιού, (μτφ.) μυώ (σε μυστικά τέχνης κ.λπ.)

idioms:

• blood bank    τράπεζα αίματος
• blood brother    αδερφοποιτός, σταυραδερφός
• blood count    ανάλυση αίματος, μέτρηση αιμοσφαιρίων
• blood feud    αιματηρή βεντέτα
• blood group    ομάδα αίματος
• blood heat    θερμοκρασία αίματος, κανονική θερμοκρασία σώματος
• blood lust    δίψα για αίμα
• blood money    λύτρα αίματος, αποζημίωση στην οικογένεια θύματος, αιματοβαμμένα χρήματα, αντίτιμο εγκλήματος ή προδοσίας
• blood poisoning    σηψαιμία, πυαιμία
• blood pressure    πίεση αίματος
• blood relation    συγγενής εξ αίματος
• blood sport    αιματηρά σπορ (π.χ. κυνήγι, ταυρομαχίες)
• blood ties    δεσμοί αίματος
• blood transfusion    μετάγγιση αίματος
• blood type    ομάδα αίματος
• blood vessel    αιμοφόρο αγγείο
• draw blood    χύνω αίμα, προκαλώ αιματοχυσία
• make someone's blood boil    ανεβάζω το αίμα κάποιου στο κεφάλι

Italiano (Italian)
sangue

idioms:

• blood bank    banca del sangue
• blood brother    fratello di sangue
• blood count    esame del sangue
• blood feud    faida
• blood group    gruppo sanguigno
• blood heat    temperatura corporea
• blood lust    sete di sangue
• blood money    prezzo del tradimento
• blood poisoning    avvelenamento del sangue
• blood pressure    pressione sanguigna
• blood relation    consanguineo
• blood sport    caccia
• blood ties    vincoli del sangue, legami di sangue
• blood transfusion    trasfusione sanguigna
• blood type    gruppo sanguigno
• blood vessel    vaso sanguigno
• clotted blood    sangue coagulato
• draw blood from    salassare
• drop of blood    goccia di sangue
• let blood    salassare
• lose blood    perdere sangue
• low blood pressure    ipotensione
• make someone's blood boil    far andare su tutte le furie
• red blood cell    globulo rosso
• shed blood    spargere sangue
• white blood cell    globulo bianco

Português (Portuguese)
n. - sangue (m)
v. - sangrar

idioms:

• bad blood    inimizade (f)
• blood bank    banco (m) de sangue
• blood brother    irmão (m) de sangue
• blood count    contagem (f) de glóbulos (Med.)
• blood feud    rixa (f) entre famílias
• blood group    grupo (m) sangüíneo
• blood heat    temperatura (f) corporal
• blood lust    forte desejo (m) de matar ou ferir
• blood money    dinheiro (m) pago para um assassino
• blood poisoning    septicemia (f) (Med.)
• blood pressure    pressão (f) arterial
• blood relation    parente (m) consangüíneo
• blood sport    caça (f)
• blood ties    laços (m pl) de sangue
• blood transfusion    transfusão (f) de sangue
• blood type    tipo (m) sangüíneo
• blood vessel    vaso (m) sangüíneo
• clotted blood    sangue (m) coagulado
• draw blood from    retirar sangue de
• drop of blood    gota (f) de sangue
• let blood    sangrar
• lose blood    perder sangue
• low blood pressure    pressão (f) arterial baixa
• make someone's blood boil    fazer o sangue ferver, irritar
• red blood cell    hemácias (f pl) (Med.)
• shed blood    derramamento (m) de sangue
• spill blood    matar
• stem blood    estancar o sangue
• stop blood    parar o sangue
• white blood cell    leucócitos (m pl) (Med.)

Русский (Russian)
кровь

idioms:

• bad blood    вражда
• blood bank    донорский пункт
• blood brother    брат, побратим
• blood count    анализ крови
• blood feud    кровная вражда
• blood group    группа крови
• blood heat    температура человеческого тела
• blood lust    жажда крови
• blood money    деньги, уплаченные наемному убийце, деньги, уплаченные вместо мести за убийство
• blood poisoning    заражение крови
• blood pressure    кровяное давление
• blood relation    кровное родство
• blood sport    охота
• blood ties    кровные узы
• blood transfusion    переливание крови
• blood type    группа крови
• blood vessel    кровеносный сосуд
• clotted blood    сгустки крови
• draw blood from    пускать кровь кому-либо
• drop of blood    капля крови
• let blood    пускать кровь
• lose blood    истекать кровью
• low blood pressure    низкое кровяное давление
• make someone's blood boil    доводить кого-либо до белого каления
• red blood cell    красная кровяная клетка
• shed blood    пролить кровь
• spill blood    пролить кровь
• stem blood    остановить поток крови
• stop blood    остановить кровотечение
• white blood cell    белая кровяная клетка

Español (Spanish)
n. - sangre
v. tr. - sangrar

idioms:

• blood bank    banco de sangre
• blood brother    hermano carnal
• blood count    recuento de glóbulos sanguíneos
• blood feud    enemistad mortal
• blood group    grupo sanguíneo
• blood heat    temperatura del cuerpo
• blood lust    sed de sangre
• blood money    precio de la sangre
• blood poisoning    envenenamiento de la sangre
• blood pressure    tensión arterial
• blood relation    pariente consanguíneo
• blood sport    deportes cruentos
• blood ties    parentesco
• blood transfusion    transfusión de sangre
• blood type    grupo sanguíneo
• blood vessel    vaso sanguíneo
• make someone's blood boil    hacer hervir la sangre a uno

n. - Indígena norteamericano

Svenska (Swedish)
n. - blod
v. - ge smak på blod, åderlåta

中文（简体）(Chinese (Simplified))
血, 血统, 血液

血, 血液, 脾气, 性子, 血统, 家族关系, 血气, 放血, 用血染

idioms:

• blood bank    血库
• blood brother    亲兄弟, 把兄弟
• blood count    血球计数
• blood feud    血仇
• blood group    血型
• blood heat    正常血温
• blood lust    嗜血狂, 杀戮欲
• blood money    血腥钱
• blood poisoning    血中毒, 败血症, 毒血症
• blood pressure    血压
• blood relation    血缘关系, 嫡亲
• blood sport    流血运动
• blood ties    血亲关系
• blood transfusion    输血, 输血法
• blood type    血型
• blood vessel    血管
• make someone's blood boil    使某人愤怒

中文（繁體）(Chinese (Traditional))
n. - 血, 血統, 血液

n. - 血, 血液, 脾氣, 性子, 血統, 家族關係, 血氣
v. tr. - 放血, 用血染

idioms:

• blood bank    血庫
• blood brother    親兄弟, 把兄弟
• blood count    血球計數
• blood feud    血仇
• blood group    血型
• blood heat    正常血溫
• blood lust    嗜血狂, 殺戮慾
• blood money    血腥錢
• blood poisoning    血中毒, 敗血症, 毒血症
• blood pressure    血壓
• blood relation    血緣關係, 嫡親
• blood sport    流血運動
• blood ties    血親關係
• blood transfusion    輸血, 輸血法
• blood type    血型
• blood vessel    血管
• make someone's blood boil    使某人憤怒

한국어 (Korean)
n. - 피, 생명, 혈통
v. tr. - ~에게 피를 맛 보이다[보이다, 뽑다]

idioms:

• make someone's blood boil    격분 시키다

n. - 일가친척, 가족

日本語 (Japanese)
n. - 血, 血液, 体液, 生命, 赤い樹液, 煽情小説, 流血, 犠牲, 血統, 血縁, 血潮, 気質
v. - 血を味わわせる, 新しい経験をさせる, 瀉血する

idioms:

• blood bank    血液銀行
• blood brother    血を分けた兄弟, 血盟した兄弟分
• blood count    血球数, 血球数測定
• blood feud    血讐
• blood group    血族, 血液型
• blood heat    血温
• blood lust    殺戮への欲望
• blood money    殺人謝礼金, 情報提供謝礼金
• blood poisoning    敗血症
• blood pressure    血圧
• blood relation    血族
• blood sport    血を見るスポーツ
• blood ties    血のつながり
• blood transfusion    輸血
• blood type    血液型
• blood vessel    血管
• clotted blood    凝血
• let blood    放血する
• make one's blood boil    憤激させる
• make someone's blood boil    激怒させる

العربيه (Arabic)
‏(الاسم) دم, دماء, أصل, عائله, نسب (فعل) جرب لأول مرة, أذاق كلب الصيد طعم الدم‏

עברית (Hebrew)
n. - ‮דם, קרבת-דם, להט, תשוקה, מוצא אתני‬
v. tr. - ‮הקיז דם‬
n. - ‮דם, קרבת-דם, הקיז דם, להט, תשוקה, מוצא אתני‬

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blood	blood glucose
blood pressure	in cold blood