Chapter 18: cardiovascular system

Into which chamber of the heart do the pulmonary veins deliver blood?

left atrium The pulmonary veins deliver oxygen-rich blood to the left atrium.

circumflex artery

runs to the apex of the heart

mitral (bicuspid) valve

valve between the left atrium and left ventricle

cardiac output

the amount of blood pumped by each ventricle in one minute

diastole

relaxation

Which of the following is NOT a role of the fibrous pericardium?

It facilitates heart contraction. The fibrous pericardium is the superficial part of the pericardium that encloses the heart. It protects the heart, prevents the heart from overfilling with blood, and anchors the heart to surrounding structures.

The superior chambers of the heart are called the __________.

atria The heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle. The atria are the superior chambers; the ventricles are inferior to the atria.

Which of the following would lead to a decrease in heart rate?

parasympathetic stimulation Sympathetic stimulation (for example, exercise) can lead to the release of epinephrine and norepinephrine, which increase heart rate. A sharp decrease in blood volume also leads to an increase in heart rate. Low metabolic rate, cold temperatures, and parasympathetic stimulation decrease heart rate.

aortic semilunar valve

prevents backflow of blood into the left ventricle

pulmonary semilunar valve

prevents backflow of blood into the right ventricle

The role of the atrioventricular node (AV node) is to __________.

slow down impulses so that the atria can contract to fill the adjacent ventricles with blood An impulse of the heart originates at the sinoatrial (SA) node. The impulse is then transmitted to the atrioventricular (AV) node, where the impulse slows down to allow the atria to completely contract, thereby filling the adjacent ventricles. The AV node then transmits the impulse to the atrioventricular bundle (bundle of His), which branches into left and right bundle branches. The bundle branches give rise to the subendocardial conducting network (Purkinje fibers), which transmit the impulse to the ventricle walls and stimulate ventricular contraction.

anterior interventricular artery

supplies blood to the interventricular septum and anterior walls of both ventricles

right marginal artery

supplies blood to the lateral right side of the myocardium

stroke volume

the volume of blood pumped by one ventricle with each heartbeat

tricuspid valve

valve between the right atrium and right ventricle

cardiac cycle

the events associated with blood flow through the heart during one complete heartbeat

In the fetus, blood from the left and right sides of the heart normally mix.

True

Which of the following is a difference between cardiac muscle and skeletal muscle?

Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic.

The P wave of an electrocardiogram represents __________.

atrial depolarization The P wave reflects the depolarization of the atria. The QRS complex shows ventricular depolarization, and the T wave is generated by ventricular repolarization. Since the QRS complex is so large, it obscures the wave that is generated by atrial repolarization.

The second heart sound (the "dup" of "lub-dup") is caused by the __________.

closure of the semilunar valves The first heart sound (the the "lup" of "lub-dup") is generated by the closure of the atrioventricular valves. The second heart sound (the "dup" sound) is caused by closure of the semilunar valves.

systole

contraction

Which of the following are correctly paired?

ectopic focus: an abnormal pacemaker Extrasystole, or premature contraction, can be caused by ectopic or abnormal pacemakers (also called ectopic foci). An ectopic focus can result when the sinoatrial (SA) node is defective. Additionally, some substances (such as caffeine and nicotine) consumed in excess can generate an ectopic focus. Any defect in the intrinsic conduction system of the heart can generate an irregular heart rhythm (an arrhythmia). Damage to the atrioventricular (AV) node can lead to a heart block. In a complete heart block, impulses do not reach the ventricles; as a result, the ventricles beat at their intrinsic rate, which is too slow to maintain adequate circulation. Fibrillation is characterized by rapid and irregular or out-of-phase contractions of the heart chambers.

The lining of the heart chambers is called the __________.

endocardium The layers of the heart wall from superficial to deep are the epicardium, the myocardium, and the endocardium. The endocardium lines the heart chambers.

Freshly oxygenated blood is delivered to the __________, and then it passes into the __________ to be pumped to the body tissues (systemic circuit).

left atrium; left ventricle The left side of the heart pumps blood to the body tissues and is known as the systemic circuit pump. Freshly oxygenated blood from the lungs is returned to the left atrium. From the left atrium, the blood flows into the left ventricle. The left ventricle then pumps the blood to the aorta, which distributes it to the body tissues (systemic circuit).

The most muscular chamber of the heart is the __________.

left ventricle

posterior interventricular artery

runs to the apex of the heart