BLOOD

Blood Type



BLOOD:
" INTRODUCTION
" ROLE OF BLOOD
" COMPOSITION OF BLOOD
" Plasma
" Red Blood Cells
" Blood Type
" White Blood Cells
" Platelets and Clotting
" PRODUCTION AND ELIMINATION OF BLOOD CELLS
" Red Blood Cell Diseases
" White Blood Cell Diseases
" Coagulation Diseases
" BLOOD BANKS
" Blood Transfusion
" Blood Count
" Blood donation and registry
" Blood gas analysis
" Blood sugar tests
" Blood typing and crossmatching
" Blood urea nitrogen test
" Blood-viscosity reducing drugs
Circulatory System:
" INTRODUCTION
" COMPONENTS OF THE CIRCULATORY SYSTEM
" OPERATION AND FUNCTION
" Systemic Circulation
" Pulmonary Circulation
" Additional Functions
" Blood Pressure
" DISEASES AND DISORDERS
" HEART
Vasculature System:
" Arteries
" Veins
" Capillaries
" Vasculature of the Arm
" Vasculature of the Head
" Vasculature of the Leg
" Vasculature of the Torso

Blood Type

Blood Type, in medicine, classification of red blood cells by the presence of specific substances on their surface. Typing of red blood cells is a prerequisite for blood transfusion. In the early part of the 20th century, physicians discovered that blood transfusions often failed because the blood type of the recipient was not compatible with that of the donor. In 1901 the Austrian pathologist Karl Landsteiner classified blood types and discovered that they were transmitted by Mendelian heredity.

The four blood types are known as A, B, AB, and O. Blood type A contains red blood cells that have a substance A on their surface. This type of blood also contains an antibody directed against substance B, found on the red cells of persons with blood type B. Type B blood contains the reverse combination. Serum of blood type AB contains neither antibody, but red cells in this type of blood contain both A and B substances. In type O blood, neither substance is present on the red cells, but the individual is capable of forming antibodies directed against red cells containing substance A or B. If blood type A is transfused into a person with B type blood, anti-A antibodies in the recipient will destroy the transfused A red cells. Because O type blood has neither substance on its red cells, it can be given successfully to almost any person. Persons with blood type AB have no antibodies and can receive any of the four types of blood; thus blood types O and AB are called universal donors and universal recipients, respectively.

Other hereditary blood-group systems have subsequently been discovered. The hereditary blood constituent called Rh factor is of great importance in obstetrics and blood transfusions because it creates reactions that can threaten the life of newborn infants. More than twenty additional blood types have been discovered. Their primary importance is in legal cases involving proof of paternity. See also Genetics.

World Health Organization

Blood Clot in the Legs

Deep venous thrombosis (DVT) refers to a blood clot embedded in one of the major deep veins of the lower legs, thighs, or pelvis. A clot blocks blood circulation through these veins, which carry blood from the lower body back to the heart. The blockage can cause pain, swelling, or warmth in the affected leg.

Next: Blood Clot in the Legs

Blood Culture

A blood culture is done when a person has symptoms of a blood infection, also called bacteremia. Blood is drawn from the person one or more times and is tested in a laboratory to find and identify any microorganism present and growing in the blood. If a microorganism is found,...

Next: Blood Culture