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 present

characteristics of blood groups.

So, let’s start with blood

Blood, is a vital fluid found in humans and other animals that

provides important nourishment to all body organs and tissues and carries

away waste materials. Sometimes referred to as “the river of life,” blood

is pumped from the heart through a network of blood vessels collectively

known as the circulatory ssystem.

An adult human has about 5 to 6 liters (1 to 2 gal) of blood, which is

roughly 7 to 8 percent of total body weight. Infants and children have

comparably lower volumes of blood, roughly proportionate to their smaller

size. The volume of blood in an individual fluctuates. During dehydration,

for example while running a marathon, blood volume decreases. Blood volume

increases in circumstances such as pregnancy, when the mother’s blood needs

to carry extra oxygen and nutrients to the baby.

Finally let’s consider: ccharacteristics of blood group

1. 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 BB.

2. Type B blood contains the reverse combination.

3. Serum of blood type AB contains neither antibody, but red cells in

this type of blood contain both A and B substances.

4. 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.