Answer:
SA node
Explanation:
The SA node (called the pacemaker of the heart) sends out an electrical impulse. The upper heart chambers (atria) contract. The AV node sends an impulse into the ventricles. The lower heart chambers (ventricles) contract or pump.
kinetic energy and potential energy i believe
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A glass flask and sodium and hydrogen hope it helped
photosystem 2, photosystem 1, pumping hydrogen..., and making NADPH
