chapter 18 practice questions

Which of the following is NOT a role of the pericardium? It prevents the heart from overfilling with blood. It protects the heart. It anchors the heart to surrounding structures. It facilitates heart contraction.

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

Into which chamber of the heart do the pulmonary veins deliver blood? right ventricle right atrium left ventricle left atrium

left atrium

Freshly oxygenated blood is delivered to the __________ and then it passes into the __________ to be pumped to the entire body. right atrium; right ventricle left atrium; left ventricle right ventricle; right atrium left ventricle; left atrium

left atrium; left ventricle

The role of the atrioventricular node (AV node) is to __________. initiate a sinus rhythm conduct impulses to the sinoatrial node (SA node) slow down impulses so that the atria can contract to fill the adjacent ventricles with blood initiate ventricular depolarization

slow down impulses so that the atria can contract to fill the adjacent ventricles with blood

The superior chambers of the heart are called the __________. atria coronary chambers ventricles cavea

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

The second heart sound (the 'dup' of 'lub-dup') is caused by the __________. opening of the atrioventricular valves opening of the semilunar valves closure of the atrioventricular valves closure of the semilunar valves

closure of the semilunar valves The first heart sound (the 'lub' 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.

Which is correctly paired? -heart block: uncoordinated atrial and -ventricular contraction -arrhythmia: AV node failure -fibrillation: premature contraction -ectopic focus: an abnormal pacemaker

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 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 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 most muscular chamber of the heart is the __________. right atrium left atrium right ventricle left ventricle

left ventricle The left side of the heart is the systemic circuit pump. Since the left ventricle pumps blood to the entire body, it makes sense that it is a more powerful pump than the right ventricle, which only needs to pump blood to the nearby lungs. The powerful pumping ability of the left ventricle is due in part to its thick musculature; the walls of the left ventricle are about three times thicker than the walls of the right ventricle. Since the demands on the left ventricle are so great, it receives the highest percentage of the coronary blood supply.

Which of the following would lead to a decrease in heart rate? exercise parasympathetic stimulation sharply decreased blood volume norepinephrine

parasympathetic stimulation

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

True

Which of the following is a difference between cardiac muscle and skeletal muscle? Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic. Unlike skeletal muscle cells, cardiac muscle cells do not rely on an influx of calcium ions for depolarization. Unlike skeletal muscle, cardiac muscle does not use a sliding filament mechanism for contraction. Unlike skeletal muscle, cardiac muscle is not striated.

Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic. Cardiac muscle is striated and utilizes the sliding-filament mechanism for contraction, like skeletal muscle. Both cardiac and skeletal muscle depend upon calcium ion influx to lead to depolarization. Unlike skeletal muscle, cardiac muscle cells have a greater concentration of mitochondria, giving cardiac cells a high resistance to fatigue. Cardiac muscle cells are highly dependent upon oxygen in order to carry out aerobic respiration. Cardiac muscle cells die faster than skeletal muscle cells if deprived of oxygen. Additionally, the plasma membranes of cardiac muscle cells interlock, while skeletal muscle cell fibers are independent. Cardiac cells can be autorhythmic, a property not seen in skeletal muscle fibers.

The P wave of an electrocardiogram represents __________. atrial depolarization ventricular depolarization atrial repolarization ventricular repolarization

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 lining of the heart chambers is called the __________. myocardium epicardium endocardium pericardium

endocardium