A&P II Ch.20 Cardiovascular System

1. A first-degree block is caused by ________________. 2. The rate of ventricular conduction is best determined by the _______________________ on an ECG. 3. An ECG tracing from someone with a third-degree AV block is best described as a tracing with a ______________________.

1. delay of the action potential between the SA and AV nodes 2. the number of QRS complexes present within a specific unit of time 3. 2:1 ratio of P waves to QRS complexes

1. The semilunar valves remain open throughout the ____________________ phase of the cardiac cycle. 2. The atria remain in diastole throughout both the _______________________ phases of the cardiac cycle.

1. late ventricular systole 2. ventricular systole & ventricular diastole

A) The image above is a tracing of B) The ions that contribute to these changes in potential are C) The dashed line represents

A) a pacemaker potential B) sodium, potassium, and calcium C) threshold

Match the component of the electrocardiogram to the correct definition. P wave QRS complex T wave PQ (PR) interval QT interval

Atrial depolarization Ventricular depolarization Ventricular repolarization Equates to atrial systole (and beginning diastole) Equates to ventricular systole (and beginning diastole)

Which of the following is false regarding the sarcoplasmic reticulum in cardiac muscle cells?

It has enlarged terminal cisternae similar to skeletal muscle cells.

Which of the following would be most likely if the heart skeleton was absent, but SA node activity was normal?

The atria and ventricles would contract nearly simultaneously.

Which of the following does not occur during ventricular systole?

The ventricles fill with blood.

Where is blood moving during the period of ejection?

Ventricles to great vessels

Match the cardiac cycle event with the correct ventricular activity. AV valves are open: Semilunar valves are open: First heart sound: Second heart sound: Third heart sound:

Ventricular diastole Ventricular systole Ventricular systole Ventricular diastole Ventricular diastole

The refractory period

- prevents tetanic contractions from occurring. - contributes to the rhythmicity of contractions. - ensures that muscle contraction and most of relaxation has been completed before another cycle begins.

Place the components of the electrical conducting system in order from the initiation of an action potential until the end.

1) SA node 2) Atrial Myocardium 3) AV Node 4) AV Bundle 5) Right & Left Bundle Branches 6) Purkinje Fibers

1) Heart rate in excess of 100 beats per minute 2) Cessation of P wave; new low heart rate due to AV node acting as pacemaker; normal QRS complex and T wave 3) Heart rate less than 60 bpm 4) PR interval greater than 0.2 second 5) No QRS complexes; no rhythmic contraction of the myocardium; many patches of asynchronously contracting ventricular muscle

1) Tachycardia 2) SA node block 3) Bradycardia 4) AV node block 5) Ventricular fibrillation

a. Just after the QRS complex, the ________occurs. b. Upon the left ventricular pressure reaching 80 mm Hg, the aortic semilunar valve opens. This is the ________. c. Atrial systole completes ventricular filling during _________. d. The T wave is completed and the ventricles are repolarizing during the ________.

a) period of isovolumetric contraction b) period of ejection c) . active ventricular filling d) period of isovolumetric relaxation

a. The __________ is a higher-pitched sound resulting from closure of the aortic and pulmonary semilunar valves at the beginning of ventricular diastole. b. The __________ is a low-pitched sound caused by vibration of the atrioventricular valves and surrounding fluid as the valves close at the beginning of ventricular systole. c. The __________ is occasionally heard in some normal people, particularly those who are thin and young. It is caused by blood flowing in a turbulent fashion into the ventricles.

a) second heart sound b) first heart sound c) third heart sound

In the conduction system of the heart, ___________.

action potentials pass slowly through the atrioventricular node

During __________, the AV valves are open, and blood flows from the atria into the ventricles.

passive ventricular filling

In the heart, an action potential originates in the

sinoatrial node.

The atrioventricular valves open during

ventricular diastole.

Indicate whether each statement is true or false. The heart skeleton consists of a bony plate of osseous tissue between the atria and ventricles. The heart skeleton forms rings around the atrioventricular and semilunar valves and provides support for them. The heart skeleton serves as insulation between the atria and the ventricles and provides a rigid site for attachment of the cardiac muscles. The heart skeleton serves as an electrical insulator between the atria and the ventricles.

False True True True

Identify the correct sequence of an action potential travelling through the heart.

Sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers