Explain how a supernova would create the environment for the formation of our solar system.

Match the following terms describing electrical events with the correct phases of the cardiac cycle. the ventricular muscle cells depolarize at the start of this phase. during this phase, na+ entry through the funny channels causes the pacemaker potential of sa nodal cells to gradually become less negative until it reaches threshold. the ventricular muscle cells repolarize right before this phase. the cytosolic concentration of calcium in the contractile cells of the ventricle is highest during this phase. a. isovolumetric relaxation b. ventricular ejection c. isovolumetric contraction d. ventricular filling

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

All eukaryotic cells contain small bodies called