Question 1

The significance of the "atrial kick" is that it is the contraction of the:

Accepted Answer

Left atrial contraction, "atrial kick," provides a significant increase of blood to the left ventricle.

Question 2

Which of the following statements does not accurately describe the pericardium?

Accepted Answer

The pericardium is composed of a surface layer of mesothelium over a thin layer of connective tissue.

Question 3

Which cardiac chamber has the thinnest wall and why?

Accepted Answer

The two atria have the thinnest walls because they are low-pressure chambers that serve as storage units and conduits for blood that is emptied into the ventricles.

Question 4

Although both produce vasoconstriction, the effects of norepinephrine are quantitatively more vasoconstrictive than the effects of epinephrine.

Accepted Answer

Epinephrine, the hormone released from the adrenal medulla, causes vasoconstriction in most vascular beds (exceptions are coronary, liver, and skeletal muscle). However, the effects of norepinephrine (from the sympathetic nervous system and adrenal medulla) are quantitatively more vasoconstrictive than the effects of epinephrine.

Question 5

To produce an action potential, the sinoatrial node must be stimulated by the autonomic nervous system.

Accepted Answer

The heart's nodes and conduction system generate cardiac action potentials independently but the autonomic nervous system influences the rate of impulse generation (firing), depolarization, and repolarization of the myocardium and the strength of atrial and ventricular contraction.

Question 6

Ventricular hypertrophy results in the capillaries of the heart becoming more extensive as well as numerous.

Accepted Answer

In ventricular hypertrophy (enlargement of the ventricular myocardium), the capillary network does not expand along with muscle fiber size. Therefore, the same number of capillaries must now perfuse a larger area. This results in decreased exchange of oxygen and nutrients.

Question 7

The mitral and tricuspid valves close after the ventricles are filled with blood because the:

Accepted Answer

During ventricular relaxation the two atrioventricular valves open and blood flows from the higher-pressure atria to the relaxed ventricles. With increasing ventricular pressure these valves close and prevent backflow into the atria as the ventricles contract.

Question 8

The aortic valve obstructs coronary blood flow by pushing against the openings of the coronary arteries during systole.

Accepted Answer

Because of their location, the aortic valve cusps obstruct coronary blood flow by pushing against the openings of the coronary arteries during systole.

Question 9

Blood contained within the atria and ventricles is a recognized source of oxygen for the cells of the heart.

Accepted Answer

The blood within the heart chambers does not supply oxygen and other nutrients to the cells of the heart. Like all other organs, including the lungs, heart structures are nourished by vessels of the systemic circulation.

Question 10

Occlusion of the left anterior descending artery during a myocardial infarction would interrupt blood supply to the:

Accepted Answer

The left anterior descending artery (LAD), also called the anterior interventricular artery, delivers blood to portions of the left and right ventricles and much of the interventricular septum.

Question 11

Which chamber of the heart endures the highest pressures?

Accepted Answer

Pressure is greatest in the systemic circulation, driven by the left ventricle.

Question 12

Veins are less compliant than arteries.

Accepted Answer

Although the elastic arteries are more compliant than the muscular arteries, the veins are more compliant than either type of artery.

Question 13

Although the heart is innervated by the sympathetic nervous system, neural impulses are not needed to maintain the cardiac cycle.

Accepted Answer

Although the heart is innervated by the autonomic nervous system (sympathetic and parasympathetic fibers), neural impulses are not needed to maintain the cardiac cycle. Thus the heart will beat in the absence of any nervous connection.

Question 14

Autoregulation ensures constant coronary blood flow despite normal shifts in perfusion pressure.

Accepted Answer

Autoregulation in the coronary circulation maintains constant blood flow at perfusion pressures (mean arterial pressure) between 60 and 180 mm Hg when other influencing factors are held constant. Thus autoregulation ensures constant coronary blood flow despite shifts in the perfusion pressure within the stated range.

Question 15

Oxygenated blood flows through the:

Accepted Answer

The four pulmonary veins, two from the right lung and two from the left lung, carry oxygenated blood from the lungs to the left side of the heart.

Question 16

A function of the papillary muscles is to _____ valves.

Accepted Answer

The papillary muscles are extensions of the myocardium that pull the cusps together and downward at the onset of ventricular contraction, thus preventing their backward expulsion into the atria.

Question 17

The arteries in the peripheral vasculature system are less able to stretch and recoil than the arteries of the great vessels.

Accepted Answer

The elastic arteries have a very thick tunica media that contains more elastic fibers than smooth muscle fibers. Elastic arteries include the aorta and its major branches and the pulmonary trunk. The muscular arteries are the medium-size and small arteries farther from the heart and contain fewer elastic fibers and more muscle fibers than the elastic arteries because being farther from the heart, they have less need of the properties of stretch and recoil. The function of the muscular arteries is to distribute blood to arterioles throughout the body.

Question 18

Metabolic and hormonal agents produce changes in the heart and circulatory system faster than autonomic neural transmission.

Accepted Answer

Autonomic neural transmission produces changes in the heart and circulatory system faster than metabolic or humoral agents.

Question 19

During the cardiac cycle, the aortic and pulmonic valves close after the ventricles contract because the:

Accepted Answer

When the ventricles relax, blood fills the cusps and causes their free edges to meet in the middle of the vessel, closing the valve and preventing any backflow.

Question 20

Occlusion of the circumflex artery during a myocardial infarction would interrupt blood supply to the:

Accepted Answer

The circumflex artery supplies blood to the left atrium and the lateral wall of the left ventricle. The circumflex artery often branches to the posterior surfaces of the left atrium and left ventricle.

Quiz 29: Structure and Function of the Cardiovascular and Lymphatic Systems