The cardiac cycle consists of a distinct relaxation and contraction phase. Which term is

Visit this site (http://openstaxcollege.org/l/heartvalve) to observe an echocardiogram of actual heart valves opening and closing. Although much of the heart has been removed from this gif loop so the chordae tendineae are not visible, why is their presence more critical for the atrioventricular valves (tricuspid and mitral) than the semilunar (aortic and pulmonary) valves?

Which of the following is not important in preventing backflow of blood? a. chordae tendineae b. papillary muscles c. AV valves d. endocardium

Which valve separates the left atrium from the left ventricle? a. mitral b. tricuspid c. pulmonary d. aortic

Which of the following lists the valves in the order through which the blood flows from the vena cava through the heart? a. tricuspid, pulmonary semilunar, bicuspid, aortic semilunar b. mitral, pulmonary semilunar, bicuspid, aortic semilunar c. aortic semilunar, pulmonary semilunar, tricuspid, bicuspid d. bicuspid, aortic semilunar, tricuspid, pulmonary semilunar

Which chamber initially receives blood from the systemic circuit? a. left atrium b. left ventricle c. right atrium d. right ventricle

The ________ layer secretes chemicals that help to regulate ionic environments and strength of contraction and serve as powerful vasoconstrictors. a. pericardial sac b. endocardium c. myocardium d. epicardium

The myocardium would be the thickest in the ________. a. left atrium b. left ventricle c. right atrium d. right ventricle

In which septum is it normal to find openings in the adult? a. interatrial septum b. interventricular septum c. atrioventricular septum d. all of the above

Which of the following is unique to cardiac muscle cells? a. Only cardiac muscle contains a sarcoplasmic reticulum. b. Only cardiac muscle has gap junctions. c. Only cardiac muscle is capable of autorhythmicity d. Only cardiac muscle has a high concentration of mitochondria.

Which of the following is unique to cardiac muscle cells? a. Only cardiac muscle contains a sarcoplasmic reticulum. b. Only cardiac muscle has gap junctions. c. Only cardiac muscle is capable of autorhythmicity d. Only cardiac muscle has a high concentration of mitochondria.

Which portion of the ECG corresponds to repolarization of the atria? a. P wave b. QRS complex c. T wave d. none of the above: atrial repolarization is masked by ventricular depolarization

Which component of the heart conduction system would have the slowest rate of firing? a. atrioventricular node b. atrioventricular bundle c. bundle branches d. Purkinje fibers

The cardiac cycle consists of a distinct relaxation and contraction phase. Which term is typically used to refer ventricular contraction while no blood is being ejected? a. systole b. diastole c. quiescent d. isovolumic contraction

Most blood enters the ventricle during ________. a. atrial systole b. atrial diastole c. ventricular systole d. isovolumic contraction

The first heart sound represents which portion of the cardiac cycle? a. atrial systole b. ventricular systole c. closing of the atrioventricular valves d. closing of the semilunar valves

Ventricular relaxation immediately follows ________. a. atrial depolarization b. ventricular repolarization c. ventricular depolarization d. atrial repolarization

The force the heart must overcome to pump blood is known as ________. a. preload b. afterload c. cardiac output d. stroke volume

The cardiovascular centers are located in which area of the brain? a. medulla oblongata b. pons c. mesencephalon (midbrain) d. cerebrum

In a healthy young adult, what happens to cardiac output when heart rate increases above 160 bpm? a. It increases. b. It decreases. c. It remains constant. d. There is no way to predict.

What happens to preload when there is venous constriction in the veins? a. It increases. b. It decreases. c. It remains constant. d. There is no way to predict.

Which of the following is a positive inotrope? a. Na+ b. K c. Ca2+ d. both Na+ and K+

The earliest organ to form and begin function within the developing human is the ________. a. brain b. stomach c. lungs d. heart

Of the three germ layers that give rise to all adult tissues and organs, which gives rise to the heart? a. ectoderm b. endoderm c. mesoderm d. placenta

The two tubes that eventually fuse to form the heart are referred to as the ________. a. primitive heart tubes b. endocardial tubes c. cardiogenic region d. cardiogenic tubes

Which primitive area of the heart will give rise to the right ventricle? a. bulbus cordis b. primitive ventricle c. sinus venosus d. truncus arteriosus

The pulmonary trunk and aorta are derived from which primitive heart structure? a. bulbus cordis b. primitive ventricle c. sinus venosus d. truncus arteriosus

Describe how the valves keep the blood moving in one direction.

Why is the pressure in the pulmonary circulation lower than in the systemic circulation?

Why is the plateau phase so critical to cardiac muscle function?

How does the delay of the impulse at the atrioventricular node contribute to cardiac function?

How do gap junctions and intercalated disks aid contraction of the heart?

Why do the cardiac muscles cells demonstrate autorhythmicity?

Describe one cardiac cycle, beginning with both atria and ventricles relaxed.

Why does increasing EDV increase contractility?

Why is afterload important to cardiac function?

Why is it so important for the human heart to develop early and begin functioning within the developing embryo?

Describe how the major pumping chambers, the ventricles, form within the developing heart.