Chapter 19: Cardiovascular System: Heart

During a cardiac cycle, how many of the four chambers contract at any one time?

A) 1 B) 2 C) 4 D) Highly variable, depending on the heart beat rate E) None of the choices is correct. B) 2

Which vein drains the posterior aspect of the ventricles of the heart?

A) Great cardiac vein B) Middle cardiac vein C) Small cardiac vein D) Circumflex vein B) Middle cardiac vein

The shutting of the semilunar valves occurs during which phase?

A) Isovolumetric contraction B) Ventricular ejection C) Isovolumetric relaxation D) Atrial contraction and ventricular filling E) Late ventricular diastole C) Isovolumetric relaxation

Which circuit of the cardiovascular system includes the left ventricle and aorta?

A) Pulmonary circuit B) Cardio circuit C) Coronary circuit D) Systemic circuit D) Systemic circuit

Someone with a heart block would have

A) a long P-R interval. B) a long T-P interval. C)a short P-R interval. D) a short T-P interval. A) a long P-R interval.

Which can be used to characterize blood flow in the human body? a: There is a unidirectional blood flow. b: Arteries always carry oxygenated blood. c: Veins always carry deoxygenated blood. d: Arteries carry blood away from the heart. e: Veins carry blood toward the heart.

A) a, c, d, e B) a, b, c, d, e C) a, d, e D) b, c, d, e E) d, e C) a, d, e

Which are functions performed by the fibrous skeleton of the heart? a: Separates the atria and ventricles b: Anchors the heart valves c: Provides electrical insulation between the atria and ventricles d: Provides the framework for the attachment of the myocardium e: None of these are true functions of the fibrous skeleton of the heart

A) a, d B) b, d C) a, c, d D) a, b, c, d E) e D) a, b, c, d

Metabolically, cardiac muscle relies on

A) aerobic metabolism using glycolysis of glycogen to meet most ATP demands. B) aerobic metabolism using many mitochondria and a rich supply of myoglobin. C) anaerobic metabolism using glycolytic enzymes to quickly generate ATP. D) anaerobic metabolism using myoglobin, creatin kinase, and ketone bodies. B) aerobic metabolism using many mitochondria and a rich supply of myoglobin.

The opening and closing of the heart valves is caused by

A) contraction and relaxation of papillary muscles that pull on heart strings. B) pressure changes of alternating contraction and relaxation during the cardiac cycle. C) contraction of the smooth muscle in the walls of the great vessels leaving the heart. D) action potentials within the cusps of the valves. B) pressure changes of alternating contraction and relaxation during the cardiac cycle.

Vagal tone refers to the

A) decreasing of the heart rate below its inherent rhythm by parasympathetic stimulation. B) decreasing of the heart rate below its inherent rhythm by sympathetic stimulation. C) increasing of the heart rate above its inherent rhythm by sympathetic stimulation. D) increasing of the heart rate above its inherent rhythm by parasympathetic stimulation. A) decreasing of the heart rate below its inherent rhythm by parasympathetic stimulation.

As with action potentials in other types of cells, the repolarization of cardiac muscle cells involves the

A) entrance of calcium through voltage-gated channels. B) exit of potassium through voltage-gated channels. C) entrance of sodium through voltage-gated channels. D) binding of ACh to ACh receptor. E) simultaneous closure of sodium channels and opening of calcium channels. B) exit of potassium through voltage-gated channels.

The units for perfusion of blood are typically

A) grams per minute. B) milliliters per minute per gram. C) millimiters per hour per kilogram. D) liters per gram. C) beats per minute per gram. B) milliliters per minute per gram.

The pericardial cavity is between the

A) heart muscle and serous pericardium. B) fibrous and serous layers of the pericardium. C) visceral and parietal layers of the serous pericardium. D) parietal and myocardial layers of the fibrous pericardium. C) visceral and parietal layers of the serous pericardium.

Occlusion of blood vessels tends to lead to

A) increases in perfusion. B) increases in capillary exchange. C) inadequate blood supply and damage to body tissues. D) defibrillation of cardic muscle cell contraction. C) inadequate blood supply and damage to body tissues.

The membrane of a contractile cardiac muscle cell contains

A) no calcium pumps. B) calcium pumps that move calcium out of the cell. C) calcium pumps that move calcium into the cell. D) calcium pumps that open and allow calcium to diffuse down its concentration gradient to reach equilibrium. B) calcium pumps that move calcium out of the cell.

The plateau phase of an action potential

A) occurs only in skeletal muscle and makes those fibers' contractions most forceful. B) leads to tetanic contractions in smooth and skeletal muscle. C) allows cardiac muscle cells to contract and then relax without locking up. D) allows cardiac muscle cells to exhibit synchronous fibrillation. C) allows cardiac muscle cells to contract and then relax without locking up.

During ventricular contraction

A) only the AV valves open. B) only the AV valves close. C) only the semilunar valves close. D) the semilunar valves close and the AV valves open. E) the semilunar valves open and the AV valves close. E) the semilunar valves open and the AV valves close.

A drug that decreased calcium levels in a muscle cell and thereby lowered the number of crossbridges formed during the heart's contractions would be a

A) positive chronotropic agent. B) negative chronotropic agent. C) positive inotropic agent. D) negative inotropic agent. D) negative inotropic agent.

The base of the heart faces in the _____________ directions.

A) anterior and inferior B) anterior and superior C) posterior and superior D) posterior and inferior E) None of these choices is correct. C) posterior and superior

The left and right coronary arteries

A) are interconnected with several high-volume anastomoses allowing for well perfused alternate blood paths. B) are functional end arteries because the blockage of one of them leads to tissue death in the area it supplies. B) are functional end arteries because the blockage of one of them leads to tissue death in the area it supplies.

The pulmonary trunk receives blood from the right ventricle and conducts it toward the lung. The pulmonary trunk is a(n)

A) artery. B) capillary. C) vein. A) artery.

Cardiac output is usually expressed in

A) beats per minute. B) mL per beat. C) mm Hg. D) liters per minute. D) liters per minute.

What is the sequence of events in the transmission of an impulse through the heart muscle? a: AV node b: AV bundle c: SA node d: Through the atria e: Through the ventricles f: Bundle branches g: Purkinje fibers

A) c, d, a, b, f, g, e B) d, b, a, c, f, g, e C) b, a, d, c, f, g, e D) f, g, d, c, b, a, e E) c, d, a, f, b, g, e A) c, d, a, b, f, g, e

Coronary vessels are open when the heart is

A) contracting. B) relaxed. B) relaxed.

During the plateau phase of a cardiac muscle cell's action potential, the membrane stays

A) depolarized as potassium exits and calcium enters. B) depolarized as potassium enters and calcium exits. C) repolarized as sodium enters and calcium exits. D) hyperpolarized as sodium and calcium exit. E) hyperpolarized as potassium enters and calcium exits. A) depolarized as potassium exits and calcium enters.

Atrial contraction occurs just before

A) isovolumetric relaxation. B) atrial relaxation and ventricular filling. C) ventricular ejection. D) isovolumetric contraction. D) isovolumetric contraction.

Blood moves into and then out of a heart chamber because

A) it moves along its pressure gradient, and that gradient depends on contraction and relaxation during the cardiac cycle. B) it is under constant pressure, but its movement is dictated by the control of valve openings and closures. C) the veins and arteries constrict and dilate to propel and attract blood. A) All of the choices are correct. A) it moves along its pressure gradient, and that gradient depends on contraction and relaxation during the cardiac cycle.

The fossa ovalis appears just above the opening of the coronary sinus within the

A) left atrium. B) left ventricle. C) right atrium. D) right ventricle. C) right atrium.

Norepinephrine is considered a positive chronotropic agent because it causes

A) less calcium to enter heart cells, which leads to lower risk of heart attack. B) more forceful contractions during each heart rate. C) an increase in the firing rate of SA node cells. D) thyroid hormone to have a steadying effect on heart activity. E) heart cell membrane potentials to become more positive during action potentials. C) an increase in the firing rate of SA node cells.

Large doses of certain stimulants can lead to dangerous increases in heart rates. Such a stimulant is a

A) positive chronotropic agent. B) negative chronotropic agent. C) positive inotropic agent. D) negative inotropic agent. A) positive chronotropic agent.

At the AV node of the conduction system, the action potential is

A) rapidly advanced due to the cells being large and well connected by gap junctions. B) rapidly advanced due to the cells being small and well insulated by myelin. C) delayed due to the cells being small and having few gap junctions. D) delayed due to the cells being large and having many leakage channels. C) delayed due to the cells being small and having few gap junctions.

For the repolarization phase of an SA nodal cell action potential,

A) sodium and potassium channels open. B) calcium channels open and sodium channels close. C) calcium and potassium channels close. D) calcium channels close and potassium channels open. E) sodium and chloride channels open. D) calcium channels close and potassium channels open.

Cardiac reserve is

A) the potential increase in stroke volume someone would show if they engaged in athletic training. B) the increase in cardiac output an individual is capable of demonstrating during vigorous exercise. C) the amount of blood left in the heart after the ventricle has contracted during cardiac cycles at rest. D) the blood that the heart uses to nourish its cardiac muscle and does not put into general circulation. B) the increase in cardiac output an individual is capable of demonstrating during vigorous exercise.