How does blood cells are formed

Hematopoiesis 

Uncontrollable bleeding, dead internal organs and continuous bacterial infections: that would be the state of our bodies if we didn't have blood cells. Lucky for us, we do! They carry oxygen, defend the body against pathogens, and stop bleeding.

Blood cells are created throughout our life time in order to make sure that we have healthy ones at all times. Can you imagine how worn out our blood cells would be if the ones we were born with were still working in our bodies?New blood cells are created at the same rate as the ones that die.

The process of producing new blood cells is called hematopoiesis. Hematopoiesis started taking place long before you ever able to read this lesson - it began when you were a developing fetus inside of your mom. The process took place in your liver and spleen during that time. Once you were born - and ever since - it takes place in your bone marrow, found at the ends of your long bones.

Process

Interestingly, hematopoiesis forms three different types of blood cells from the same beginning cell, which is able to become more than one type of a cell. Cells with that ability are called stem cells. The beginning stem cell in hematopoiesis is classified as a hematopoietic stem cell, meaning it is a stem cell that can become any type of blood cell, and it's called a hemocytoblast. The process to make each type of blood cell is different.