:a –
erythrocytes; b –
neutrophil;c –
eosinophil; d –
lymphocyte.]]
(SEM) image of a normal
red blood cell, a
platelet, and a
white blood cell.]]
Blood is a specialized
bodily fluid that delivers necessary substances to the body's
cells (in
animals) – such as nutrients and
oxygen – and transports
waste products away from those same cells.
In vertebrates, it is composed of blood cells suspended in a liquid called blood plasma. Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume), and contains dissipated proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), platelets and blood cells themselves. The blood cells are mainly red blood cells (also called RBCs or erythrocytes) and white blood cells, including leukocytes and platelets. The most abundant cells in vertebrate blood are red blood cells. These contain hemoglobin, an iron-containing protein, which facilitates transportation of oxygen by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is almost entirely transported extracellularly dissolved in plasma as bicarbonate ion.
Vertebrate blood is bright red when its hemoglobin is oxygenated. Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some molluscs use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this "blood" does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their tracheal system to suffice for supplying oxygen.
Jawed vertebrates have an adaptive immune system, based largely on white blood cells. White blood cells help to resist infections and parasites. Platelets are important in the clotting of blood. Arthropods, using hemolymph, have hemocytes as part of their immune system.
Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.
Medical terms related to blood often begin with hemo- or hemato- (also spelled haemo- and haemato-) from the Ancient Greek word (haima) for "blood". In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen.
Functions
Blood performs many important functions within the body including:
Supply of oxygen to tissues (bound to hemoglobin, which is carried in red cells)
Supply of nutrients such as glucose, amino acids, and fatty acids (dissolved in the blood or bound to plasma proteins (e.g., blood lipids))
Removal of waste such as carbon dioxide, urea, and lactic acid
Immunological functions, including circulation of white blood cells, and detection of foreign material by antibodies
Coagulation, which is one part of the body's self-repair mechanism (blood clotting after an open wound in order to stop bleeding)
Messenger functions, including the transport of hormones and the signaling of tissue damage
Regulation of body pH
Regulation of core body temperature
Hydraulic functions
Constituents of human blood
-anticoagulated blood. Left tube: after standing, the RBCs have settled at the bottom of the tube. Right tube: contains freshly drawn blood.]]
Blood accounts for 8% of the human body weight, with an average density of approximately 1060 kg/m
3, very close to pure water's density of 1000 kg/m
3. The average adult has a
blood volume of roughly 5
liters (1.3 gal), composed of plasma and several kinds of cells (occasionally called
corpuscles); these formed elements of the blood are erythrocytes (
red blood cells, RBCs), leukocytes (
white blood cells), and thrombocytes (
platelets). By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, and white cells about 0.7%.
Whole blood (plasma and cells) exhibits non-Newtonian, viscoelastic fluid dynamics; its flow properties are adapted to flow effectively through tiny capillary blood vessels with less resistance than plasma by itself. In addition, if all human hemoglobin were free in the plasma rather than being contained in RBCs, the circulatory fluid would be too viscous for the cardiovascular system to function effectively.
Cells
One microliter of blood contains:
4.7 to 6.1 million (male), 4.2 to 5.4 million (female) erythrocytes: In most mammals, mature red blood cells lack a
nucleus and
organelles. They contain the blood's
hemoglobin and distribute oxygen. The red blood cells (together with
endothelial vessel cells and other cells) are also marked by
glycoproteins that define the different
blood types. The proportion of blood occupied by red blood cells is referred to as the
hematocrit, and is normally about 45%. The combined surface area of all red blood cells of the human body would be roughly 2,000 times as great as the body's exterior surface.
4,000–11,000 leukocytes: White blood cells are part of the
immune system; they destroy and remove old or aberrant cells and cellular debris, as well as attack infectious agents (
pathogens) and foreign substances. The cancer of leukocytes is called
leukemia.
200,000–500,000 thrombocytes: Blood that has a pH below 7.35 is too
acidic, whereas blood pH above 7.45 is too
alkaline. Blood pH,
partial pressure of oxygen (pO
2), partial pressure of carbon dioxide (pCO
2), and
HCO3− are carefully regulated by a number of
homeostatic mechanisms, which exert their influence principally through the
respiratory system and the
urinary system in order to control the
acid-base balance and respiration. An
arterial blood gas will measure these. Plasma also circulates
hormones transmitting their messages to various tissues. The list of normal
reference ranges for various blood electrolytes is extensive.
Bones are especially affected by blood pH as they tend to be used as a mineral source for pH buffering. Consuming a high ratio of animal protein to vegetable protein is implicated in bone loss in women.
Blood in non-human vertebrates
Human blood is typical of that of mammals, although the precise details concerning cell numbers, size,
protein structure, and so on, vary somewhat between species. In non-mammalian vertebrates, however, there are some key differences:
Red blood cells of non-mammalian vertebrates are flattened and ovoid in form, and retain their cell nuclei
There is considerable variation in the types and proportions of white blood cells; for example, acidophils are generally more common than in humans
Platelets are unique to mammals; in other vertebrates, small, nucleated, spindle cells are responsible for blood clotting instead
Physiology
Cardiovascular system
Blood is circulated around the body through blood vessels by the pumping action of the heart. In humans, blood is pumped from the strong left ventricle of the heart through arteries to peripheral tissues and returns to the right atrium of the heart through veins. It then enters the right ventricle and is pumped through the pulmonary artery to the lungs and returns to the left atrium through the pulmonary veins. Blood then enters the left ventricle to be circulated again. Arterial blood carries oxygen from inhaled air to all of the cells of the body, and venous blood carries carbon dioxide, a waste product of metabolism by cells, to the lungs to be exhaled. However, one exception includes pulmonary arteries, which contain the most deoxygenated blood in the body, while the pulmonary veins contain oxygenated blood.
Additional return flow may be generated by the movement of skeletal muscles, which can compress veins and push blood through the valves in veins toward the right atrium.
The blood circulation was famously described by William Harvey in 1628.
Production and degradation of blood cells
In vertebrates, the various cells of blood are made in the
bone marrow in a process called
hematopoiesis, which includes
erythropoiesis, the production of red blood cells; and myelopoiesis, the production of white blood cells and platelets. During childhood, almost every human bone produces red blood cells; as adults, red blood cell production is limited to the larger bones: the bodies of the vertebrae, the breastbone (sternum), the ribcage, the pelvic bones, and the bones of the upper arms and legs. In addition, during childhood, the
thymus gland, found in the
mediastinum, is an important source of
lymphocytes.
The proteinaceous component of blood (including clotting proteins) is produced predominantly by the
liver, while hormones are produced by the
endocrine glands and the watery fraction is regulated by the
hypothalamus and maintained by the
kidney.
Healthy erythrocytes have a plasma life of about 120 days before they are degraded by the spleen, and the Kupffer cells in the liver. The liver also clears some proteins, lipids, and amino acids. The kidney actively secretes waste products into the urine.
Oxygen transport
About 98.5% of the
oxygen in a sample of arterial blood in a healthy human breathing air at sea-level pressure is chemically combined with the Hgb. About 1.5% is physically dissolved in the other blood liquids and not connected to Hgb. The
hemoglobin molecule is the primary transporter of oxygen in
mammals and many other species (for exceptions, see below). Hemoglobin has an oxygen binding capacity of between 1.36 and 1.37 ml O
2 per gram Hemoglobin, which increases the total
blood oxygen capacity seventyfold, compared to if oxygen solely was carried by its solubility of 0.03 mL O
2 per liter blood per mmHg
partial pressure of oxygen (approximately 100 mmHg in arteries). to the body. In a healthy adult at rest,
oxygen consumption is approximately 200 - 250 mL/min, (70 to 78%) Oxygen saturation this low is considered dangerous in an individual at rest (for instance, during surgery under anesthesia. Sustained hypoxia (oxygenation of less than 90%), is dangerous to health, and severe hypoxia (saturations of less than 30%) may be rapidly fatal.
A fetus, receiving oxygen via the placenta, is exposed to much lower oxygen pressures (about 21% of the level found in an adult's lungs), and, so, fetuses produce another form of hemoglobin with a much higher affinity for oxygen (hemoglobin F) in order to function under these conditions.
Carbon dioxide transport
When blood flows through capillaries, carbon dioxide diffuses from the tissues into the blood. Some carbon dioxide is dissolved in the blood. A part of CO
2 reacts with hemoglobin and other proteins to form
carbamino compounds. The remaining carbon dioxide is converted to
bicarbonate and
hydrogen ions through the action of RBC
carbonic anhydrase. Most carbon dioxide is transported through the blood in the form of bicarbonate ions.
Carbon dioxide (CO2), the main cellular waste product is carried in blood mainly dissolved in plasma, in equilibrium with bicarbonate (HCO3-) and carbonic acid (H2CO3). 86–90% of CO2 in the body is converted into carbonic acid, which can quickly turn into bicarbonate, the chemical equilibrium being important in the pH buffering of plasma. Blood pH is kept in a narrow range (pH between 7.35 and 7.45).
Invertebrates
In
insects, the blood (more properly called
hemolymph) is not involved in the transport of oxygen. (Openings called
tracheae allow oxygen from the air to diffuse directly to the tissues). Insect blood moves nutrients to the tissues and removes waste products in an open system.
Other invertebrates use respiratory proteins to increase the oxygen-carrying capacity. Hemoglobin is the most common respiratory protein found in nature. Hemocyanin (blue) contains copper and is found in crustaceans and mollusks. It is thought that tunicates (sea squirts) might use vanabins (proteins containing vanadium) for respiratory pigment (bright-green, blue, or orange).
In many invertebrates, these oxygen-carrying proteins are freely soluble in the blood; in vertebrates they are contained in specialized red blood cells, allowing for a higher concentration of respiratory pigments without increasing viscosity or damaging blood filtering organs like the kidneys.
Giant tube worms have unusual hemoglobins that allow them to live in extraordinary environments. These hemoglobins also carry sulfides normally fatal in other animals.
Color
Hemoglobin
Hemoglobin is the principal determinant of the color of blood in vertebrates. Each molecule has four heme groups, and their interaction with various molecules alters the exact color. In
vertebrates and other hemoglobin-using creatures, arterial blood and capillary blood are bright red, as oxygen imparts a strong red color to the heme group. Deoxygenated blood is a darker shade of red; this is present in veins, and can be seen during
blood donation and when venous blood samples are taken. Blood in
carbon monoxide poisoning is bright red, because
carbon monoxide causes the formation of
carboxyhemoglobin. In
cyanide poisoning, the body cannot utilize oxygen, so the venous blood remains oxygenated, increasing the redness. While hemoglobin-containing blood is never blue, there are several conditions and diseases wherein the color of the heme groups make the skin appear blue. If the heme is oxidized,
methaemoglobin, which is more brownish and cannot transport oxygen, is formed. In the rare condition
sulfhemoglobinemia, arterial hemoglobin is partially oxygenated, and appears dark red with a bluish hue (
cyanosis).
Veins in the skin appear blue for a variety of reasons only weakly dependent on the color of the blood. Light scattering in the skin, and the visual processing of color play roles as well.
Skinks in the genus Prasinohaema have green blood due to a buildup of the waste product biliverdin.
Hemocyanin
The blood of most
mollusks – including
cephalopods and
gastropods – as well as some
arthropods, such as
horseshoe crabs, is blue, as it contains the copper-containing protein hemocyanin at concentrations of about 50 grams per liter. and it turns dark blue when exposed to the oxygen in the air, as seen when they bleed. A healthy adult can lose almost 20% of blood volume (1 L) before the first symptom, restlessness, begins, and 40% of volume (2 L) before
shock sets in.
Thrombocytes are important for blood
coagulation and the formation of blood clots, which can stop bleeding. Trauma to the internal organs or bones can cause
internal bleeding, which can sometimes be severe.
* Dehydration can reduce the blood volume by reducing the water content of the blood. This would rarely result in shock (apart from the very severe cases) but may result in orthostatic hypotension and fainting.
Disorders of circulation
* Shock is the ineffective perfusion of tissues, and can be caused by a variety of conditions including blood loss, infection, poor cardiac output.
* Atherosclerosis reduces the flow of blood through arteries, because atheroma lines arteries and narrows them. Atheroma tends to increase with age, and its progression can be compounded by many causes including smoking, high blood pressure, excess circulating lipids (hyperlipidemia), and diabetes mellitus.
* Coagulation can form a thrombosis, which can obstruct vessels.
* Problems with blood composition, the pumping action of the heart, or narrowing of blood vessels can have many consequences including hypoxia (lack of oxygen) of the tissues supplied. The term ischemia refers to tissue that is inadequately perfused with blood, and infarction refers to tissue death (necrosis), which can occur when the blood supply has been blocked (or is very inadequate).
Hematological disorders
Anemia
* Insufficient red cell mass (anemia) can be the result of bleeding, blood disorders like thalassemia, or nutritional deficiencies; and may require blood transfusion. Several countries have blood banks to fill the demand for transfusable blood. A person receiving a blood transfusion must have a blood type compatible with that of the donor.
* Sickle-cell anemia
Disorders of cell proliferation
* Leukemia is a group of cancers of the blood-forming tissues.
* Non-cancerous overproduction of red cells (polycythemia vera) or platelets (essential thrombocytosis) may be premalignant.
* Myelodysplastic syndromes involve ineffective production of one or more cell lines.
Disorders of coagulation
* Hemophilia is a genetic illness that causes dysfunction in one of the blood's clotting mechanisms. This can allow otherwise inconsequential wounds to be life-threatening, but more commonly results in hemarthrosis, or bleeding into joint spaces, which can be crippling.
* Ineffective or insufficient platelets can also result in coagulopathy (bleeding disorders).
* Hypercoagulable state (thrombophilia) results from defects in regulation of platelet or clotting factor function, and can cause thrombosis.
Infectious disorders of blood
* Blood is an important vector of infection. HIV, the virus that causes AIDS, is transmitted through contact with blood, semen or other body secretions of an infected person. Hepatitis B and C are transmitted primarily through blood contact. Owing to blood-borne infections, bloodstained objects are treated as a biohazard.
* Bacterial infection of the blood is bacteremia or sepsis. Viral Infection is viremia. Malaria and trypanosomiasis are blood-borne parasitic infections.
Carbon monoxide poisoning
Substances other than oxygen can bind to hemoglobin; in some cases this can cause irreversible damage to the body.
Carbon monoxide, for example, is extremely dangerous when carried to the blood via the lungs by inhalation, because carbon monoxide irreversibly binds to hemoglobin to form
carboxyhemoglobin, so that less hemoglobin is free to bind oxygen, and fewer oxygen molecules can be transported throughout the blood. This can cause suffocation insidiously. A fire burning in an enclosed room with poor ventilation presents a very dangerous hazard, since it can create a build-up of carbon monoxide in the air. Some carbon monoxide binds to hemoglobin when smoking
tobacco.
Medical treatments
Blood products
Blood for transfusion is obtained from human donors by
blood donation and stored in a
blood bank. There are many different
blood types in humans, the
ABO blood group system, and the
Rhesus blood group system being the most important. Transfusion of blood of an incompatible blood group may cause severe, often fatal, complications, so
crossmatching is done to ensure that a compatible blood product is transfused.
Other blood products administered intravenously are platelets, blood plasma, cryoprecipitate, and specific coagulation factor concentrates.
Intravenous administration
Many forms of medication (from
antibiotics to
chemotherapy) are administered intravenously, as they are not readily or adequately absorbed by the digestive tract.
After severe acute blood loss, liquid preparations, generically known as plasma expanders, can be given intravenously, either solutions of salts (NaCl, KCl, CaCl2 etc.) at physiological concentrations, or colloidal solutions, such as dextrans, human serum albumin, or fresh frozen plasma. In these emergency situations, a plasma expander is a more effective life-saving procedure than a blood transfusion, because the metabolism of transfused red blood cells does not restart immediately after a transfusion.
Bloodletting
In modern
evidence-based medicine, bloodletting is used in management of a few rare diseases, including
hemochromatosis and
polycythemia. However,
bloodletting and
leeching were common unvalidated interventions used until the 19th century, as many diseases were incorrectly thought to be due to an excess of blood, according to
Hippocratic medicine.
History
According to the
Oxford English Dictionary, the word "blood" originated before the 12th century. The word is derived from Middle English, which is derived from the Old English word
blôd, which is akin to the Old High German word
bluot, meaning blood. The modern German word is
(das) Blut.
Classical Greek medicine
In classical Greek medicine, blood was associated with air, with Springtime, and with a merry and gluttonous (
sanguine) personality. It was also believed to be produced exclusively by the
liver.
Hippocratic medicine
In
Hippocratic medicine, blood was considered to be one of the
four humors, the others being
phlegm,
yellow bile, and
black bile.
Cultural and religious beliefs
Due to its importance to life, blood is associated with a large number of beliefs. One of the most basic is the use of blood as a symbol for family relationships through birth/parentage; to be "related by blood" is to be related by ancestry or descendance, rather than marriage. This bears closely to
bloodlines, and sayings such as "
blood is thicker than water" and "
bad blood", as well as "
Blood brother". Blood is given particular emphasis in the Jewish and Christian religions because
Leviticus 17:11 says "the life of a creature is in the blood." This phrase is part of the Levitical law forbidding the drinking of blood or eating meat with the blood still intact instead of being poured off.
Mythic references to blood can sometimes be connected to the life-giving nature of blood, seen in such events as childbirth, as contrasted with the blood of injury or death.
Indigenous Australians
In many
indigenous Australian Aboriginal peoples' traditions,
ochre (particularly red) and blood, both high in
iron content and considered
Maban, are applied to the bodies of dancers for ritual. As Lawlor states:
In many Aboriginal rituals and ceremonies, red ochre is rubbed all over the naked bodies of the dancers. In secret, sacred male ceremonies, blood extracted from the veins of the participant's arms is exchanged and rubbed on their bodies. Red ochre is used in similar ways in less-secret ceremonies. Blood is also used to fasten the feathers of birds onto people's bodies. Bird feathers contain a protein that is highly magnetically sensitive.
Lawlor comments that blood employed in this fashion is held by these peoples to attune the dancers to the invisible energetic realm of the Dreamtime. Lawlor then connects these invisible energetic realms and
magnetic fields, because iron is
magnetic.
European paganism
Among the
Germanic tribes (such as the
Anglo-Saxons and the
Norsemen), blood was used during their sacrifices; the
Blóts. The blood was considered to have the power of its originator, and, after the butchering, the blood was sprinkled on the walls, on the statues of the gods, and on the participants themselves. This act of sprinkling blood was called
blóedsian in
Old English, and the terminology was borrowed by the
Roman Catholic Church becoming
to bless and
blessing. The
Hittite word for blood,
ishar was a cognate to words for "oath" and "bond", see
Ishara.
The
Ancient Greeks believed that the blood of the gods,
ichor, was a substance that was poisonous to mortals.
As a relic of Germanic Law the cruentation, an ordeal where the corpse of the victim was supposed to start bleeding in the presence of the murderer was used until the early 17th. century.
Judaism
In
Judaism, blood cannot be consumed even in the smallest quantity (
Leviticus 3:17 and elsewhere); this is reflected in Jewish
dietary laws (
Kashrut). Blood is purged from
meat by
salting and soaking in water.
Another ritual involving blood involves the covering of the blood of fowl and game after slaughtering (Leviticus 17:13); the reason given by the Torah is: "Because the life of the animal is [in] its blood" (ibid 17:14).
Also if a person of the orthodox Jewish faith suffers a violent death, religious laws order the collection of their blood for burial with them.
Christianity
Some Christian churches, including Roman Catholicism, Eastern Orthodoxy, Oriental Orthodoxy, and the Assyrian Church of the East teach that, when consecrated, the Eucharistic wine actually becomes the blood of Jesus for worshippers to drink. Thus in the consecrated wine, Jesus becomes spiritually and physically present. This teaching is rooted in the Last Supper, as written in the four gospels of the Bible, in which Jesus stated to his disciples that the bread that they ate was his body, and the wine was his blood. "This cup is the new testament in my blood, which is shed for you." ().
Various forms of Protestantism, especially those of a Wesleyan or Presbyterian lineage, teach that the wine is no more than a symbol of the blood of Christ, who is spiritually but not physically present. Lutheran theology teaches that the body and blood is present together "in, with, and under" the bread and wine of the Eucharistic feast.
Christ's blood is the means for the atonement of sins. Also, ″… the blood of Jesus Christ his [God] Son cleanseth us from all sin.” (1 John 1:7), “… Unto him [God] that loved us, and washed us from our sins in his own blood.” (Revelation 1:5), and “And they overcame him (Satan) by the blood
of the Lamb [Jesus the Christ], and by the word of their testimony …” (Revelation 12:11).
At the Council of Jerusalem, the apostles prohibited Christians from consuming blood (except Jesus's), probably because this was a command given to Noah (Genesis 9:4, see Noahide Law). This command continued to be observed by the Eastern Orthodox.
Islam
Consumption of food containing blood is forbidden by
Islamic dietary laws. This is derived from the statement in the
Qur'an, sura
Al-Ma'ida (5:3): "Forbidden to you (for food) are: dead meat, blood, the flesh of swine, and that on which has been invoked the name of other than Allah."
Blood is considered as unclean and in Islam cleanliness is part of the faith, hence there are specific methods to obtain physical and ritual status of cleanliness once bleeding has occurred. Specific rules and prohibitions apply to menstruation, postnatal bleeding and irregular vaginal bleeding.
Jehovah's Witnesses
Based on their interpretation of scriptures such as Acts 15:28, 29 ("Keep abstaining...from blood."), Jehovah's Witnesses neither consume blood nor accept transfusions of whole blood or its major components: red blood cells, white blood cells, platelets (thrombocytes), and plasma. Members may personally decide whether they will accept medical procedures that involve their own blood or substances that are further fractionated from the four major components.
Chinese and Japanese culture
In Chinese popular culture, it is often said that if a man's nose produces a small flow of blood, he is experiencing sexual desire. This often appears in
Chinese-language and
Hong Kong films as well as in
Japanese culture parodied in
anime and
manga. Characters, mostly males, will often be shown with a
nosebleed if they have just seen someone
nude or in little clothing, or if they have had an erotic thought or fantasy; this is based on the idea that a male's blood pressure will spike dramatically when aroused.
Blood libel
Various religious and other groups have been falsely accused of using human blood in rituals; such accusations are known as
blood libel. The most common form of this is
blood libel against Jews. Although there is no ritual involving human blood in Jewish law or custom, fabrications of this nature (often involving the murder of children) were widely used during
the Middle Ages to justify
Antisemitic persecution.
Vampire legends
Vampires are mythical creatures that drink blood directly for sustenance, usually with a preference for human blood. Cultures all over the world have myths of this kind; for example the '
Nosferatu' legend, a human who achieves damnation and immortality by drinking the blood of others, originates from Eastern European folklore.
Ticks,
leeches, female
mosquitoes,
vampire bats, and an assortment of other natural creatures do consume the blood of other animals, but only bats are associated with vampires. This has no relation to vampire bats, which are
new world creatures discovered well after the origins of the European myths.
Applications
In the applied sciences
Blood residue can help
forensic investigators identify weapons, reconstruct a criminal action, and link suspects to the crime. Through
bloodstain pattern analysis, forensic information can also be gained from the spatial distribution of bloodstains.
Blood residue analysis is also a technique used in archeology.
In art
Blood is one of the body fluids that has been used in art. In particular, the performances of
Viennese Actionist Hermann Nitsch,
Franko B,
Lennie Lee,
Ron Athey,
Yang Zhichao, and
Kira O' Reilly, along with the photography of
Andres Serrano, have incorporated blood as a prominent visual element.
Marc Quinn has made sculptures using frozen blood, including a cast of his own head made using his own blood.
In genealogy & family history
The term,
blood, is used in
genealogical circles to refer to one's
ancestry,
origins, and
ethnic background, as in the word,
bloodline. Other terms where blood is used in a family history sense are
blue-blood,
royal blood,
mixed-blood and
blood relative.
See also
Autotransfusion
Blood as food: see black pudding and tiết canh
Blood donation
Blood pressure
Blood substitutes ("Artificial blood")
Blood test
Hemophobia
List of human blood components
Taboo food and drink: Blood
Oct-1-en-3-one ("Smell" of blood)
References
External links
Blood Groups and Red Cell Antigens. Free online book at NCBI Bookshelf ID: NBK2261
Category:Hematology
Category:Tissues
