Simplify the complex fraction. 
Definitions:
Atrioventricular Node
A part of the heart's electrical system situated between the atria and ventricles that regulates the timing of heart muscle contractions.
Action Potential
Brief reversal of the charge difference across a neuron membrane.
Veins
Blood vessels that carry blood toward the heart, typically carrying deoxygenated blood from the tissues back to the heart except in the case of pulmonary veins.
Hemostasis
The physiological process by which bleeding ceases, involving blood vessel constriction and clot formation.
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