​What is Pathology - What role does calcium play in acute cell injury?

​What is Pathology - What role does calcium play in acute cell injury?
 An increase in the concentration of free calcium ions in the hyaloplasm(cytosol) is associated with cell injury . These calcium ions come from the extracellular fluid, the mitochondrial compartment, and the RER's cisterns. By activating multiple enzymes, ionised calcium enhances the 
negative effects of hypoxia:
a)Lytic ATPase: Degrades ATP, reducing energy storage even more. 
b) Phospholipases: These enzymes degrade the function of plasma or mitochondrial membranes by removing phospholipids. 
c)Proteases: These enzymes break down proteins in the cell membrane or cytoskeleton. &
d) Endonucleases: Endonucleases are enzymes that operate on RNA and DNA. 

All of these alterations are initially reversible, but they can lead to irreversible cell harm if they are continued or increased.