in humans only
temp increases(thermoreceptors)------feedback--------->hypothalamus(control centre)--------negative feedback---------------------------->sweat glands(afffector)(secret sweat)---------.temp decreases(back to set value approx 37C)
action potential is gay!
its simple its when the node of ranvier becomes permiable to NA+(sodium ions) and so this chemical enters the nside and becomes rapidaly positive relative to the outside. this is action potential and this allows the nerve impulse to pass through.
for cataracts the existing technology called 'phakoemulsifier. its where the lens is melted and sucked out and a plastic lens is inserted into the eye.