Global Calcium Waves
Global calcium waves are calcium signals that propagate through the entire cell. They are initiated by stimulation of the IP3 receptors, which leads to the stimulation of an amplifier, phospholipase C. This triggers a cascade which leads to the release of calcium from ion channels based on the endoplasmic reticulum within the cell.
Intracellular and Intercellular Global Calcium Waves
Global calcium waves can be categorised into intracellular or intercelluar waves. During intracellular calcium waves, calcium spreads throughout the whole cell, via diffusion and calcium induced calcium release (CICR).
Intercellular global calcium waves differ from intracellular calcium waves as the signal doesn't stop at the plasma membrane. It transmits across a monolayer of cells via gap junctions, which are permeable to Ca2+ and IP3. The signal stays strong as it is regenerated. Intercellular global calcium waves are present in beating cilia. The cell is stimulated by a foreign body landing on the cell, which promotes a calcium propagated signal throughout the cell, which leads to the beating of the cilia all in the same direction in order to remove the foreign body.