Which statement regarding the structure of the heart is correct?
- AThe semilunar valves close when the pressure in the ventricles falls lower than the pressure in the arteries.
- BA muscle called the septum separates the atria from the ventricles.
- CThere is a small patch of tissue in the right atrium that acts to delay the electrical impulse.
- DClosure of valves in the veins prevents backflow of blood into the ventricles.