What is the first structure that contracts in a fish heart?Multiple choice question.The sinus venosusThe atriumThe conus arteriosusThe ventricle

In a fish, electrical impulses that cause the heart to contract are initiated in theMultiple choice question.conus arteriosus.SA node.ventricle.sinus venosus.

Which of the following structures is found between the right atrium and the right ventricle in a mammal?Multiple choice question.The SA nodeThe aortic valveThe bicuspid valveThe tricuspid valve

The opening of coronary sinus empties into what chamber of the heart?Group of answer choicesLeft atriumleft ventricleRight atriumRight ventricle

From what structure/vessel do the left and right coronary arteries arise?Multiple choice question.pulmonary trunkleft atriumright atriumaorta

What structure empties blood into the left ventricle?Multiple choice question.left atriumpulmonary veinsright ventricleaorta