Which structure carries the electrical impulse from the AV node toward the apex of the heart?

The coronary sulcus (atrioventricular groove) primarily marks the boundary between the:

If the SA node fails, which structure can assume pacemaker activity at a slower rate?

Steroid hormones require membrane receptors to enter target cells.

A patient with chronic kidney disease has a low red blood cell count. Which mechanism best explains this finding?

Which chamber receives blood directly from the pulmonary veins?

Which characteristic distinguishes endocrine signaling from nervous system signaling? Endocrine, 

A decrease in platelet count would most directly impair:

A hormone that binds to an intracellular receptor is most likely:

The AV node delays electrical conduction to allow ventricular filling.