Which of the following is important for muscle contraction and nerve impulse transmission?

• Ca²⁺ ions

• Mg²⁺ ions

• Both (a) and (b)

• Fe²⁺ ions

A.

Ca²⁺ ions

Ca²⁺ ions are essential for muscle contraction, neutro- muscular functions and nerve impulse transmission. During its transmission, impulse arrives at a synaptic knob, Ca²⁺ ions diffuse into the knobs from surrounding tissue fluid.

It basically triggers a process in which numerous synaptic vesicles fuse with the membrane of the knob and the areas of fusion break down, releasing the contents of vesicles into the fluid of synaptic clefts.