One day you are walking on a concrete surface and you fall and scrape your knee. The wound starts to bleed. Later, a scab has formed.
Scabs are created when platelets in your blood are sent to go and collect at a wound site. They dry up as the crusty, rough cover over the wound. As the scab continues to cover the wound, new skin is being made underneath.
This new skin is formed when the skin on the edges of the wound duplicate and create new skin cells. This process happens when the GPCR’s, or, G-protein coupled receptors on the outside of the skin cells retrieve messages from other proteins which convey that the skin on the edge of a wound must duplicate and make new skin underneath. Cell division is the name for the process when a cell divides to create two identical daughter cells.
Cell division is made up of four phases: prophase, metaphase, anaphase, and telophase.
The prophase is sort of like a ‘preparation’ to divide. The nuclear envelope that surrounds the nucleus of a cell starts to dissolve and protein structures are forming into place.
The metaphase is when the actual dividing is starting to take place. A spindle is created by the microtubules in the cell and a polar force on the edges of the spindle is causing the cell to become oblong.
The anaphase is the second-to-last stage before the division. Here, the free chromosomes inside the cell are moving to the opposite ends of the cell where it has become oblong.
In the telophase, new nuclei have been formed in the almost-separate cells. A cleavage furrow is the last connection between the newly created cells. Now, a cleanup has started inside the cell.
Cytokinesis is essentially the real ‘dividing’ of the cell to make two cells. Cytokinesis happens after the four phases and moves the cell apart into two cells.
So all this happens just to make even a scrape on the knee heal.