#27 Calcium Causes Our Muscles To Contract
The process of rigor mortis (stiffening of the body) sets in about two-four after death, attains its maximum intensity at about 12 hours, and then ebbs away after 48 hours from the time of death.
But what causes this process? Our muscle cells have pumps located in their membranes that control the flow of calcium. Upon death, the pumps stop functioning and the calcium seeps in the cells, causing the muscles to become rigid.