Today I’m going to talk about: blood I’ve divided my presentation into two parts: First I’d like to talk about Blood and second I’ll presentcharacteristics of blood groups. So, let’s start with blood

Blood, is a vital fluid found in humans and other animals thatprovides important nourishment to all body organs and tissues and carriesaway waste materials. Sometimes referred to as “the river of life,” bloodis pumped from the heart through a network of blood vessels collectivelyknown as the circulatory system. An adult human has about 5 to 6 liters (1 to 2 gal) of blood, which isroughly 7 to 8 percent of total body weight. Infants and children havecomparably lower volumes of blood, roughly proportionate to their smallersize. The volume of blood in an individual fluctuates. During dehydration,for example while running a marathon, blood volume decreases. Blood volumeincreases in circumstances such as pregnancy, when the mother’s blood needsto carry extra oxygen and nutrients to the baby.

Finally let’s consider: characteristics of blood group

1. Blood type A contains red blood cells that have a substance A ontheir surface. This type of blood also contains an antibody directedagainst substance B, found on the red cells of persons with blood type B. 2. Type B blood contains the reverse combination. 3. Serum of blood type AB contains neither antibody, but red cells inthis type of blood contain both A and B substances. 4. In type O blood, neither substance is present on the red cells, butthe individual is capable of forming antibodies directed against red cellscontaining substance A or B. If blood type A is transfused into a person with B type blood, anti-Aantibodies 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 noantibodies and can receive any of the four types of blood; thus blood typesO and AB are called universal donors and universal recipients,respectively.