Chapter 20 Heart Lecture Quiz

The following are structural components of the conducting system of the heart. 1. Purkinje fibers 2. AV bundle 3. AV node 4. SA node 5. bundle branches The sequence in which excitation would move through this system is

4,3,2,5,1

A patient has an end-diastolic volume of 125 ml. A heart attack has weakened her left ventricle so it can pump a stroke volume of only 40 ml. Calculate her end-systolic volume.

85ml

Considering the left ventricle, why does isovolumetric ventricular contraction occur during ventricular systole?

Aortic pressure is higher than ventricular pressure and the ventricle must pressurize the blood to open the aortic valve.

The principle that increasing the end-diastolic volume results in a corresponding increase in the stroke volume is known as

Frank-Starling principle.

Cardiac output can be increased by all of the following except

decreasing ejection fraction

The ________ is the amount of blood in a ventricle after it has contracted and before it begins to refill.

end systolic volume

If the connection between the SA node and AV node becomes blocked,

the ventricles will beat more slowly

The ________ circuit carries blood to and from the lungs.

pulmonary

The contraction phase of the cardiac cycle is called

systole

The normal pacemaker of the heart is located in

the sinoatrial node