HEART

A damaged right bundle branch will prevent the passage of the action potential to the:

Purkinje fibers in the right ventricle

Predict the position of the valves during the ventricular ejection phase.

The AV valves are shut while both semilunar valves are forced open

What best describes the Frank-Starling law?

The Frank-Starling law states that the more the ventricular muscle cells are stretched, the more forcefully they contract.

Which of the following is a chronotropic agent that decreases heart rate?

acetylcholine

Where should the left ventricle send blood?

aorta

The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the:

atria

Which hormone decreases cardiac output by decreasing blood volume and preload?

atrial natriuretic peptide (ANP)

Autorhythmicity in the heart is the responsibility of:

cardiac pacemaker cells

The right side of the heart receives:

deoxygenated blood from the systemic circuit

The amount of blood remaining in each ventricle at the end of the ventricular ejection phase is called:

end systolic volume

Which of the following volumes should be the greatest?

end-diastolic volume (EDV)

What ion movement changes the membrane potential in a contractile cell from negative to positive during the rapid depolarization phase?

influx of sodium ions

As ventricular systole begins, all four heart valves are closed during the:

isovolumetric contraction phase

The pulmonary circuit involves blood flow from the heart to the:

lungs

The heart is situated in the middle of the thoracic cavity in a region known as the:

mediastinum

Which of the following is NOT part of the electrical conduction system of the heart?

papillary muscles

What is found between the visceral pericardium and the parietal pericardium?

pericardial fluid

During what phase of the action potential will calcium ions enter the contractile cell as potassium ions exit?

plateau phase

The degree of stretch experienced by the cardiac myocytes in the ventricle before they contract is called:

preload

What is the function of the valves in the heart?

prevent backflow of blood through the heart

Which vessel is guarded by a semilunar valve at its base?

pulmonary trunk

Which of the following does NOT return blood to the right atrium of the heart?

pulmonary vein

The volume of blood pumped by each ventricle in one heartbeat is known as:

stroke volume (SV)

What two values are needed in order to calculate cardiac output (CO) for a ventricle?

stroke volume (SV) and heart rate (HR)

Both the left and right atria receive blood from:

veins

During what phase does blood flow from the ventricles into the pulmonary trunk and aorta?

ventricular ejection phase