BIOL 2010 Chapter 18

True or False? The myocardium is the thickest layer in the wall of the heart.

True The myocardium is composed of cardiac muscle and forms the bulk of the heart.

The superior chambers of the heart are called the __________.

atria

The P wave of an electrocardiogram represents __________.

atrial depolarization

The lining of the heart chambers is called the __________.

endocardium

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

parasympathetic stimulation

circumflex artery

supplies blood to the left atrium and posterior walls of the left ventricle

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

closure of the semilunar valves

systole

contraction

Which is correctly paired?

ectopic focus: an abnormal pacemaker

The most muscular chamber of the heart is the __________.

left ventricle

tricuspid valve

valve between the right atrium and right ventricle

diastole

relaxation

posterior interventricular artery

runs to the apex of the heart

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

stroke volume

the volume of blood pumped by one ventricle with each heartbeat

mitral valve

valve between the left atrium and left ventricle

cardiac cycle

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

True or False? An ECG measures the contraction of the atria and the ventricles.

False An ECG measures the flow of electric current through the wall of the heart.

True or False? Cardiac output (CO) is the amount of blood pumped out by each ventricle each time the heart beats.

False Cardiac output (CO) is the amount of blood pumped out by each ventricle in one minute.

True or False? The contraction of the ventricles precedes the QRS complex.

False The QRS complex (depolarization of the ventricles) precedes ventricular contraction

True or False? The AV node is the normal pacemaker of the heart.

False The SA node, which depolarizes faster than the AV node, is the pacemaker of the heart.

True or False? The blood vessels that carry blood to and from the body tissues form the pulmonary circuit.

False The blood vessels that carry blood to and from all the body tissues form the systemic circuit.

True or False? The right and the left coronary sinuses supply oxygenated blood to the wall of the heart.

False The right and the left coronary arteries supply blood to the heart wall.

True or False? The superior vena cava, the inferior vena cava, and the coronary sinus empty into the left atrium.

False They bring blood from all over the body and empty into the right atrium.

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

It facilitates heart contraction.

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

True

True or False? When the ventricles are in systole, the atria are in diastole.

True As the atria relax, the ventricles begin contracting.

True or False? Ventricular fibrillation is a condition of rapid and irregular contractions of the ventricles.

True Defects in the intrinsic conduction system can cause either atrial or ventricular irregular heartbeats.

True or False? Both gap junctions and desmosomes are found within intercalated discs.

True Intercalated discs provide tight junctions and cell-to-cell communications between adjacent cardiac muscle cells.

True or False? Serous fluid is found in the space between the visceral and parietal layers of the pericardium.

True Serous fluid is a lubricant surrounding the outer wall of the heart.

True or False? The aortic and pulmonary semilunar valves prevent backflow of blood into the associated ventricles.

True The aortic and pulmonary semilunar valves guard the bases of the large arteries issuing from the ventricles and prevent backflow into the associated ventricles.

True or False? The first heart sound is produced by the closure of the atrioventricular valves.

True The simultaneous closure of the tricuspid and bicuspid valves causes the first sound.

True or False? The "discharging" chambers of the heart are the ventricles.

True The ventricles are the discharging chambers, or actual pumps, of the heart.

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

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

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

left atrium

Freshly oxygenated blood is delivered to the __________ and then it passes into the __________ to be pumped to the entire body.

left atrium; left ventricle

aortic semilunar valve

prevents backflow of blood into the left ventricle

pulmonary semilunar valve

prevents backflow of blood into the right ventricle

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

cardiac output

the amount of blood pumped by each ventricle in one minute