Although the blood is the same in every person, there are differences in the antigens. Each antigen gives each person an individual identity. This identity is called a blood type.
The blood pumped by the heart circulates throughout the body, carrying minerals, oxygen, nutrients, and other substances to the organs. Blood also serves to remove waste products from the body.
Blood components and their role:
Blood is produced in the bone marrow, and each of its components has a very specific task:
Red blood cells: There are approximately 25 trillion of them in the adult body (1 trillion is equal to one billion). Their job is to transport oxygen to the organs and carbon dioxide to the lungs, where it is excreted.
White blood cells: These blood cells contribute to the body's immunity and defend it against foreign bodies in case of injury or viral disease such as a cold.