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 system.
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: characteristics of blood group