Question: how does blood cells in our bodies form and why?

  1. Blood cells form from a haematopoietic stem cell (I know, terrible word. But it means to ‘make blood).

    These stem cells are in our bodies and when they divide they make a new copy of themselves and a common myleoid progenitor (CMP) or common lymphoid progenitor (CLP). These are difficult words too, but the CMP is a stem cell which can make red blood cells, platelets (which seal up wounds) and some immune cells (which protect us from disease). The CLP makes some different immune cells.

    It sounds pretty tricky, but mostly it means that there are stem cells which are able to make lots of different types of cells. Some stem cells can make any other kind of cell, some can only make blood cells.


  2. The “why” you put in there is interesting. “Why” questions are usually difficult. We produce red blood cells to carry oxygen round the body. If you’re asking why they’re made by stem cells, well that’s the way the body does a lot of stuff. The cells in our body all carry the same DNA. What makes a cell different is what bits of the DNA it decides to use. What determines that will decide what kinds of cells are made from the stem cell. This is all new science, so I imagine that not much is known. We can make stem cells produce different kinds of cells if we add stuff to the cells, but how the body does it is probably more complex.