Why is royal blood sometimes called "blue blood"?

I just heard a story of a disease associated with certain royal families, one of effects of which contributed to the birth of the term. Anyone has any sure answers?

Why is royal blood sometimes called "blue blood"?
I don't think it has to do with diseases. The word comes for the Spanish, sangre azul. I believe the term originated during the Reconquista. Blue bloods were the lighter skinned Catholics from northern spain as opposed to the darker moriscos (Moors), who were originally muslim. You could see the veins in the lighter skinned people. hence the name blue blood.
Reply:Yes the term blue blood comes from the condition of hemophilia, which most of the royal families was known to suffer from. Why did they suffer from it in such great numbers? People have said it was because most of the royal families were so closely related. A royal person could only marry another royal person, so as the generations went on you were lets say keeping it in the family i guess.


Some bleeding disorders are present at birth and are caused by rare inherited disorders. Others are developed during certain illnesses (such as vitamin K deficiency, severe liver disease), or treatments (such as use of anticoagulant drugs or prolonged use of antibiotics). They can include hemophilia and other very rare blood disorders. There are many causes of bleeding disorders, including:





von Willebrand's disease , which is an inherited blood disorder thought to affect between 1% and 2% of the population





Immune system-related diseases, such as allergic reactions to medications, or reactions to an infection





Cancer, such as leukemia, which is a blood cancer





Liver disease





Bone marrow problems





Disseminated intravascular coagulation, which is a condition often associated with child bearing, cancer, or infection, in which the body's clotting system functions abnormally





Pregnancy-associated eclampsia, also known as severe toxicity of pregnancy





Organ transplant rejection o Hemophilia A and B , which are inherited blood disorders





Exposure to snake venom





Antibodies, a type of immune system protein, that destroy blood clotting factors





Medicines, such as aspirin, heparin, warfarin, and drugs used to break up blood clots





Congenital bleeding disorders are very rare, and with the exception of hemophilia and von Willebrand disease, education about them has not been a priority of the medical community. Most have only been discovered and described in the past few decades.
Reply:This is sometimes referred to as purebred. Royals were considered pure breeds that's why they call them blue blood. as such they were rich enough to always stay indoors; thus having very pale skin and hire other people to do anything that required going outdoors. As a result of such pale skin, you could see a person's blood vessels more easily and overall skin would have a bluish tint.
Reply:Blue is the color blood is before it touches oxygen. It turns red when oxygen comes in contact with it. So Blue Blood is kind of like "pure" blood. Untouched, so it's supposed to be better than the others so to speak.





Many royal families inbreed so that may be the cause of disease.
Reply:blue blood also blue·blood (blbld)


n.





1. Noble or aristocratic descent.


2. A member of the aristocracy.





[Translation of Spanish sangre azul : sangre, blood + azul, blue (probably from the visible veins of fair-complexioned aristocrats).]





I had heard it was associated with hemophelia (which was common due to inbreeding, but the dictionary says no
Reply:its partially breeding and partially lifestyle... and partially mediaeval ignorance of body physiology.





the royal families would often try to get the fairest fiancee for their own children (i.e. lightest skin) so that the children would be ever whiter, as this made them both look higher class (dark skin coming from toiling in the fields) and more pure i.e. godly.





also, they hardly ever let much of their skin be exposed to the sun, even in summertime. therefore they didn't tan hardly at all, and mostly remained very very white (see portraits of the british Queen Elizabeth I for example).





when you get to that stage of fairness, your veins start to become rather prominent... as a load of blue lines all over you. most people recognised the blood as a red substance carried in arteries and visible surface capillaries. naturally.... it looked like, to the common man, as if they literally had "blue blood"
Reply:I think you're talking about hemophilia.