UNIT TWO - Heart Part 2 ASN

Movements of the conducting system of the heart

1. SA node activity and atrial activation begin 2. stimulus spreads scorsa the atrial surfaces and reaches the AV node 3. impulses travel along the AV bundle within the interventricular septum to the apex of the heart. Impulses also spread to the papillary muscles of the right ventricle by the moderator band 4. the impulse travels along the inter ventricular septum within the AV bundle and the bundle branches to the Purkinje fibers and, via the moderator band, to the papillary muscles of the right ventricle 5. the impulse is distributed by Purkinje fibers and relayed throughout the vernacular myocardium. Atrial contraction is completed, and ventricular contraction begins

Which event occurs during ventricular systole? a) atrioventricular valves are closed b) chord tendineae are loose c) the volume of the ventricles changes dramatically d) semilunar valves are open e) blood exits from the ventricles

a

There are many interconnections between the arterial branches of the coronary circulation, which function to maintain a constant blood supply to the muscle of the heart. These connections are called.....

anastomoses

A complete heartbeat is referred to as a(n)

cardiac cycle

The sinoatrial node, or cardiac pacemaker, is ..... a) electrically active nodal tissue located in the wall of the left ventricle b) able to cause the cardiac muscle to begin to contact at the apex c) able to cause the atria and ventricles to contract simultaneously d) embedded in the posterior wall of the right atrium, near the entrance of the superior vena cava e) embedded in the anterior two-thirds of the inter ventricular septum

d

Which of the following is TRUE of the coronary arteries? a) together they supply a small portion of the cardiac muscle with oxygen b) blood pressure in these vessels is the lowest found anywhere in the systemic circuit c) they drain into the right atrium inferior to the opening of the inferior vena cava d) they originate at the base of the ascending aorta and are the first branches off this vessel e) they transport blood directly into the ascending aorta

d

Which vessel gives rise to a circumflex branch and an anterior interventricular branch?

left coronary artery

Valves of the heart open and close due to

pressure changes

Which portion of the conducting system directly stimulates the ventricles?

purkinje fibers

Plaque buildup in the left coronary artery (LCA) would NOT affect which portion of the heart?

right atrium

The right border of the heart is supplied by the...

right marginal artery

During ventricular diastole

the semilunar valves close and the AV valves open