A&P 2 Chapter 18 Flashcards

Questions and Answers

Cardiac muscle cells are __________.

mechanically, chemically, and electrically connected to one another

Which structure provides a rapid-conduction path that tenses the papillary muscles before the ventricular myocardium contracts, preventing 'slamming' of the right AV cusps?

moderator band

Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.

ventricular diastole

Which of the following is correct about the filling of the ventricles?

Most blood flows passively into the ventricles through open AV valves. Signup and view all the answers

Describe the pressures in the atria and ventricles that would cause the opening of the AV valves.

Pressure in the atria would be greater than the pressure in the ventricles. Signup and view all the answers

What causes the aortic semilunar valve to close?

greater pressure in the aorta than in the left ventricle Signup and view all the answers

Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.

isovolumetric contraction, ventricular ejection, isovolumetric relaxation Signup and view all the answers

Increased pressure in the ventricles would close what valve(s)?

AV valves only Signup and view all the answers

Which of the following statements most accurately defines what is happening during the second phase of ventricular systole of the cardiac cycle?

Blood is being ejected from the ventricles through open semilunar valves. Signup and view all the answers

Which event does NOT happen during ventricular diastole?

Atrioventricular valves close because of the contracting ventricles. Signup and view all the answers

In the non-exercising heart, which event of the cardiac cycle lasts the longest?

atrial diastole Signup and view all the answers

Which statement is correct regarding the intrinsic heart rate?

During parasympathetic stimulation, acetylcholine released by parasympathetic neurons opens chemically gated potassium channels in the plasma membrane. Signup and view all the answers

In an ECG recording, which of the following coincides with ventricular repolarization?

T wave Signup and view all the answers

Which of the following statements is correct concerning the cardiac cycle?

In late ventricular diastole, all chambers are relaxed and filling to about seventy percent of their capacity. Signup and view all the answers

The portion of the tracing of an electrocardiogram, ECG, that represents ventricular depolarization is the __________.

QRS complex Signup and view all the answers

Study Notes

Cardiac Muscle and Conduction

Cardiac muscle cells are mechanically, chemically, and electrically interlinked, facilitating synchronized contractions.
The moderator band provides a rapid conduction path, pre-tensing the papillary muscles before ventricular contraction to prevent valve slamming.

Cardiac Cycle Phases

Ventricular diastole includes isovolumetric relaxation and ventricular filling, where the ventricles relax and fill with blood.
Most ventricular filling occurs passively through open atrioventricular (AV) valves, with minimal contribution from atrial contraction.
AV valves open when the atrial pressure exceeds ventricular pressure, allowing blood to flow into the ventricles.

Valve Functionality

The aortic semilunar valve closes due to higher pressure in the aorta compared to the left ventricle, preventing backflow.
Increased pressure in the ventricles results in the closure of the AV valves.

Phases of Ventricular Systole

The phases of the cardiac cycle after ventricular filling are isovolumetric contraction, ventricular ejection, and isovolumetric relaxation.
During the second phase of ventricular systole, blood is ejected from the ventricles through open semilunar valves as the ventricles contract.

Events During Ventricular Diastole

Atrioventricular valves do not close during ventricular diastole; they remain open as the ventricles are relaxed and filling.
Atrial diastole lasts the longest in a non-exercising heart, ensuring adequate blood return for sufficient cardiac output.

Intrinsic Heart Rate and ECG

Intrinsic heart rate is affected by parasympathetic stimulation, where acetylcholine opens potassium channels in cardiac cell membranes.
The T wave in an ECG correlates with ventricular repolarization.

Cardiac Cycle Completion

In late ventricular diastole, all heart chambers are relaxed, filling to about 70% of their capacity, completing the cardiac cycle.
The QRS complex on an ECG tracing represents the entire sequence of ventricular depolarization.

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Test your knowledge with these flashcards on Chapter 18 of Anatomy & Physiology 2. This quiz covers key concepts related to cardiac muscle cells and the cardiac cycle. Perfect for reviewing essential terms and structures!