Answer: stroke volume
Explanation:
Stroke volume is the amount of blood ejected during ventricular contraction or for each stroke of the heart.
The answer is graded potential<span>. Its made of various action potentials that depolarise the neuron incrementaly, in short interspersed intervals that do not give time for the neurons to return to resting potential. Therefore, the actions potentials, of varying sizes, grade up in sum and when they cumulatively reach the threshold level, they invoke an impulse in the nerve</span>
It is important because you need vitamins and minerals from them e.g. Scurvy no vitamin c