Chapter 20

The long plateau phase of the cardiac muscle action potential is due to decrease in the amount of calcium diffusing across the membrane. movement of fewer sodium ions across the cell membrane. increased membrane permeability to potassium ion. increased membrane permeability to sodium ions. calcium channels remaining open.

calcium channels remaining open

The amount of blood remaining in the ventricle when the semilunar valve closes is the start-diastolic volume. end-diastolic volume. end-systolic volume. stroke volume. ejection fraction.

end-systolic volume.

The pulmonary veins carry blood to the brain. liver. heart. intestines. lungs.

heart

If the pacemaker cells in the SA node become more permeable to potassium ions, the heart rate will decrease and cells will hyperpolarize. heart rate will increase. cells will depolarize. heart rate will decrease. cells will hyperpolarize.

heart rate will decrease and cells will hyperpolarize

________ is when the heart can't maintain adequate cardiac output. Coronary heart disease Fibrillation Heart failure Flutter Murmur

Heart failure

Abnormally slow depolarization of the ventricles would most change the shape of the ________ in an ECG tracing. P-R interval P wave QRS complex T wave R-T interval

QRS complex

Depolarization of the ventricles is represented on an electrocardiogram by the S wave. QRS complex. PR complex. T wave. P wave.

QRS complex

If there is a complete block between the SA node and the AV node, how would the ECG be affected? The QRS duration will be longer. The P-R interval will be shorter. The rate of P waves will be faster than the rate of QRS complexes. The ventricles will stop beating. There will be much bigger P waves.

The rate of P waves will be faster than the rate of QRS complexes

The inferior point of the heart is called the apex. mediastinum. hilum. septum. base.

apex

The ________ carry blood away from the heart. venules capillaries veins arteries arterioles

arteries

On an ECG, what phase of the cardiac cycle is masked by the QRS complex? atrial repolarization ventricular depolarization ventricular repolarization atrial depolarization

atrial repolarization

The ________ valve prevents backward flow into the left atrium. bicuspid pulmonic semilunar semicaval tricuspid

bicuspid

With each ventricular systole, blood pressure increases. the ventricles fill with blood. cardiac output decreases. blood pressure decreases. blood pressure remains steady.

blood pressure increases

During the T wave of the electrocardiogram, the ventricles are relaxing. contracting. repolarizing. depolarizing. both repolarizing and relaxing

both repolarizing and relaxing

A slower-than-normal heart rate is called tachycardia. hypercardia. hypocardia. procardia. bradycardia.

bradycardia

During the plateau phase of the cardiac action potential, which ion is entering the cardiac muscle cell? oxygen sodium potassium calcium

calcium

Heart rate is controlled by neurons of the cardiovascular center located in the higher centers. medulla oblongata. hypothalamus. thalamus. pons.

medulla oblongata

The heart lies within the ________ cavity. pericardial pleural peritoneal orbital dorsal

pericardial

Excess fluid in the ________ causes cardiac tamponade. left ventricle apex of heart visceral pericardium pericardial cavity both atria

pericardial cavity

The papillary muscles function to __________. push blood from the atria into the ventricles eject blood from the ventricles close the AV valves prevent the AV valves from reversing into the atria

prevent the AV valves from reversing into the atria

Contractions of the papillary muscles close the semilunar valves. close the atrioventricular valves. prevent the atrioventricular valves from reversing into the atria. eject blood from the atria into the ventricles. eject blood from the ventricles.

prevent the atrioventricular valves from reversing into the atria.

The ________ circuit carries blood to and from the lungs.

pulmonary

Blood leaves the right ventricle by passing through the mitral valve. aortic valve. bicuspid valve. tricuspid valve. pulmonary valve.

pulmonary valve.

The right ventricle pumps blood to the aorta. left ventricle. left atrium. right and left lungs. right atrium.

right and left lungs

Blood returning to the heart from the systemic circuit first enters the right atrium. conus arteriosus. right ventricle. left ventricle. left atrium.

right atrium

The left ventricle pumps blood to the right atrium. pulmonary circuit. aorta. lungs. right ventricle.

right atrium

The normal pacemaker of the heart is located in the Purkinje fibers. the atrioventricular node. the wall of the left ventricle. the sinoatrial node. both the left and right ventricles

sinoatrial node

Analysis of the electrocardiogram can reveal all of the following except the duration of the ventricular action potential. stroke volume. heart rate. the condition of the conducting system. the effects of drugs and poisons.

stroke volume

The ________ circuit carries blood from the aorta to the right ventricle. body pulmonary portal systemic oxygen

systemic

The contraction phase of the cardiac cycle is called depolarization. asystole. diastole. hyperpolarization. systole.

systole

A faster-than-normal heart rate is called procardia. hypocardia. hypercardia. tachycardia. bradycardia.

tachycardia

As a result of the long refractory period in the cardiac action potential, cardiac muscle cannot exhibit treppe. tonus. fatigue. recruitment. tetany.

tetany

Tetanic muscle contractions don't occur in a normal cardiac muscle because cardiac muscle tissue contracts on its own. the refractory period lasts until the muscle relaxes. neural stimulation is lacking. potassium channels outnumber sodium channels. the refractory period ends before the muscle reaches peak tension.

the refractory period lasts until the muscle relaxes.

If the connection between the SA node and AV node becomes blocked, cardiac output will increase. the ventricles will beat faster. the ventricles will beat more slowly. the atria will contract more forcefully. the ventricular beat will remain unchanged.

the ventricles will beat more slowly.

The T wave on an ECG tracing represents ventricular contraction. ventricular depolarization. atrial repolarization. ventricular repolarization. atrial depolarization.

ventricular repolarization.

The epicardium is also known as the __________. myocardium parietal pericardium endocardium visceral pericardium

visceral pericardium

The first heart sound is heard when the semilunar valves close. atria contract. AV valves close. AV valves open. blood enters the aorta.

AV valves close

Stroke volume depends on the pressure required to pump blood into the aorta. venous return of blood to the heart. end-diastolic volume. the contractility of the ventricle. All of the answers are correct.

All of the answers

A heart murmur might be caused by mitral valve insufficiency. aortic valve insufficiency. swirling of blood in the ventricle. pulmonic valve insufficiency. All of the answers are correct.

All of the answers are correct

Intercalated discs serve to transfer ________ from cell to cell. electrical signals action potentials the force of contraction ionic currents All of the answers are correct.

All of the answers are correct

In cardiac muscle, calcium ions play no role in the process of contraction. calcium ions do not bind to troponin molecules. calcium ions are not released from the sarcoplasmic reticulum. calcium ions play an important role in repolarizing the membrane after the depolarization phase. about 20 percent of the calcium ion required for contraction comes from outside the cell.

about 20 percent of the calcium ion required for contraction comes from outside the cell.

End-systolic volume is defined as the amount of blood remaining in an atrium after atrial systole. amount of blood remaining in a ventricle after contraction. amount of blood a ventricle ejects per cycle. stroke volume multiplied by the heart rate. amount of blood which backflows into a ventricle.

amount of blood remaining in a ventricle after contraction.

If you know both the heart rate and stroke volume, you can calculate the __________. end-diastolic volume cardiac output ejection fraction end-systolic volume

cardiac output

The cusps (leaflets) of atrioventricular valves attach directly to coronary sulci. papillary muscles. chordae tendineae. interatrial septa. trabeculae carneae.

chordae tendinae

The first heart sound ("lubb") is associated with atrial systole. opening of the atrioventricular valves. opening of the semilunar valves. closing of the semilunar valves. closing of the atrioventricular valves.

closing of the atrioventricular valves.

Which event occurs during ventricular systole? closing of the bicuspid and tricuspid valves release of an action potential from the sinoatrial node closing of the semilunar valves the second heart sound expansion of the ventricles

closing of the bicuspid and tricuspid valves

The P wave of the electrocardiogram is closely followed by __________. contraction of the right atrium contraction of both atria relaxation of both atria contraction of the left atrium

contraction of both atria

The first blood vessels to branch from the aorta are the ________ arteries. carotid subclavian circumflex pulmonary coronary

coronary

The ________ deliver(s) blood to the myocardium. cardiac veins coronary sinus carotid arteries coronary arteries superior vena cava

coronary arteries

The P wave of the electrocardiogram is a signal from the SA node. depolarization of the AV node. depolarization of the ventricles. repolarization of the atria. depolarization of the atria.

depolarization of the atria

The relaxation phase of the cardiac cycle is called hyperpolarization. systole. depolarization. diastole. asystole.

diastole

The ________ is the volume of blood in a ventricle at the beginning of systole. ejection fraction stroke volume start-diastolic volume end-systolic volume end-diastolic volume

end-diastolic volume

The foramen ovale in the fetal heart is located in the interatrial septum. right ventricle. left atrium. left ventricle. right atrium.

interatrial septum.

Blood returning to the heart from the pulmonary circuit first enters the right atrium. conus arteriosus. left ventricle. left atrium. right ventricle.

left atrium

Most of the mass of the heart lies on the sagittal plane. right of midline. left of midline. on the midline of the body. inferior to the midline.

left of the midline

The pulmonary arteries carry blood to the liver. intestines. lungs. heart. brain.

lungs

The coronary sulcus is a groove that separates the atrioventricular valves from the atria. marks the border between the atria and ventricles. separates the coronary arteries from the coronary veins. marks the boundary line between the right and left ventricles. marks the boundary line between the right and left atria.

marks the border between the atria and ventricles.