Ch. 42: Introduction to the Cardiovascular System

A cardiovascular clinical nurse specialist describes the dysfunctional endothelium in relation to cardiovascular disease. What is the major factor in the development of the dysfunctional endothelium?

*Atherosclerosis* Explanation: Dysfunctional endothelium is considered a major factor in atherosclerosis, acute coronary syndromes, hypertension, and thromboembolic disorders. Dysfunctional endothelium is not related to inflammation, septicemia, or tumor. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 722

An instructor is describing the unique characteristic of cells of the conducting system, explaining that these cells can generate action potentials without outside stimulation. The instructor is describing:

*Automaticity* Explanation: Automaticity is the cell's ability to generate action potentials or electrical impulses without being excited to do so by external stimuli. Conductivity refers to the ability of the cells to conduct this action potential. Contractility refers to the unified contraction of the atria and ventricles to move blood through the vascular system. Capacitancy refers to the venous system, which is distensible and flexible and able to hold large amounts of blood. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 715

While intubated for surgery, a patient has inadvertently had his vagus nerve stimulated. What effect would the surgical team expect to observe?

*Decreased heart rate as a result of parasympathetic innervation of the heart* Explanation: Vagal stimulation results in lowered heart rate as a result of parasympathetic stimulation. Vascular perfusion, contractility and afterload would not be under direct effect. Acetylcholine reuptake would not be influenced. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 716

A client is diagnosed with an atrial septal defect (ASD) that has caused a hole between the two upper chambers of the heart. What is the direct result of such a defect?

*Deoxygenated and oxygenated blood will mix* Explanation: A partition called a septum separates the right half of the heart from the left half. The right half receives deoxygenated blood while the left half receives the oxygenated blood. A defect in the septum allows for the mixing of those different forms of blood. None of the other options are a direct result of this form of defect. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 714

The client has edema resulting from heart failure (HF) in both ankles. The nurse interprets this as indicating what likely cause?

*Hydrostatic pressure is exceeding oncotic pressure.* Explanation: Edema occurs when hydrostatic pressure pushing fluid out of the capillary exceeds the oncotic pressure that is trying to pull the fluid back into the vessel. This shift of fluid accounts for the edema seen in association with HF. Variations in pulse pressure do not cause edema, nor do variations in oxygen supply. "Fluid pressure" does not exist. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 724

Fluid moves into the arterial end of a capillary due to:

*Hydrostatic pressure* Explanation: Hydrostatic pressure regulates the movement of fluids at the arterial end of the capillary; entotic pressure regulates this movement at the venous end of the capillary. It is the pressure that directs flow through the loosely connected endothelial cells of the capillary. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 721

The principles of Starling's law attempt to explain the cause of which cardiovascular dysfunction?

*Ineffective contractibility of the heart's left ventricle* Explanation: Starling's law addresses the relationship between the contractile properties of the heart and the strength of its contractions. The other options are related to the heart's conductivity not its contractibility. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 713

A backflow of blood is noted in the left ventricle from the left atrium. The patient is suffering from a defect in which valve?

*Mitral valve* Explanation: The mitral valve separates the left atrium and left ventricle. This malfunction allows the backflow of blood due to a defect in the mitral valve. The tricuspid valve separates the right atrium and right ventricle. The pulmonic valve separates the right ventricle and pulmonary artery. The aortic valve separates the left ventricle and aorta. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 715

A patient is prescribed digoxin (Lanoxin), which affects the function of the sinoatrial node. Which statement describes the function of the sinoatrial node?

*Normal pacemaker* Explanation: The sinoatrial node is the normal pacemaker of the heart. The coronary arteries originate at the base of the aorta in the aortic cusps and fill during diastole, the resting or filling phase of the cardiac cycle. Contractile properties vary among blood vessels, with some being more responsive to stimuli than others. Collateral circulation provides a sufficient blood supply for myocardial function, at least during rest. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 713

A nurse is measuring the BP of a client. The client asks what the BP measures. What is the best response by the nurse about the measurement of BP?

*Pressure of blood within the arteries* Explanation: When measuring BP, the systolic (contraction) pressure and the diastolic (relaxation) pressure of the blood within the arteries are recorded. The pressure of blood within the veins, within the heart, or within the lungs is not recorded for measuring BP. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 723

Which client diagnosis is related to left-sided heart failure?

*Pulmonary edema* Explanation: Pulmonary edema results when the left side of the heart fails; peripheral, abdominal, and liver edema occur when the right side of the heart fails. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 724

Which area of the heart is supplied by the right coronary artery?

*Right side of the heart* Explanation: The right coronary artery supplies most of the right side of the heart, including the SA node. The left circumflex artery supplies most of the left ventricle. The left anterior descending artery feeds the septum and anterior areas, including much of the conduction system. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 722

Considering the phases of the action potential of the cardiac muscle cell, what is the characteristic event associated with phase 1?

*Sodium is present in equal amounts both inside and outside of the cell* Explanation: Phase 1 is the very short period when the sodium ion concentrations are equal inside and outside the cell. All the other options are associated with Phase 2 Reference: Chapter 42: Introduction to the Cardiovascular System - Page 716

A client who has been diagnosed with blood pressure problems is eager to know more about the condition. What should the nurse explain is one of the internal processes that attempt to maintain blood pressure within normal limits?

*Special sensory receptors in blood vessel walls called baroreceptors are stimulated.* Explanation: Special sensory receptors in blood vessel walls, called baroreceptors, are stimulated by a change in blood pressure (BP). They send signals, which cause various body reactions to help maintain normal BP. The left anterior descending (LAD) artery descends along the anterior intraventricular groove to provide blood to most of the ventricular septum and the anterior portion of the left ventricle. The right and left coronary arteries extend over the heart's surface and divide into smaller branches to supply heart tissue with oxygen and nourishment. Blood moves on through the pulmonic valve during ventricular contraction to enter the pulmonary artery and lungs to receive oxygen. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 723

The nurse is caring for a client who is experiencing a backflow of blood from the left ventricle to the left atrium. How should the nurse best interpret this finding?

*The client's mitral valve is incompetent.* Explanation: The valve between the atrium and ventricle on the left side of the heart, called the mitral or bicuspid valve, is composed of two leaflets or cusps that allow the left ventricle to fill with blood and then close to prevent backflow of blood into the left atrium. If this valve is damaged, contraction of the ventricle will push blood back into the left atrium and result in inadequate cardiac output. The tricuspid valve is the valve between the right atria and ventricle. PVCs are a conduction problem that would not cause backflow of blood. Increased preload means the heart must work harder to move a larger volume of blood, but this would not cause regurgitation in the absence of a valve defect. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 714

A client, diagnosed with heart failure, would like the nurse to explain what the diagnosis means. How should the nurse explain heart failure?

*The heart muscle cannot pump as effectively as normal, causing a backup of blood.* Explanation: Heart failure occurs when the heart muscle fails to do its job of effectively pumping blood through the system and blood backs up and the system becomes congested. The rise in venous pressure that results from the backup of blood increases hydrostatic pressure on the venous end of the capillaries. The hydrostatic pressure pushing fluid out of the capillaries becomes greater than the oncotic pressure that is trying to pull the fluid back into the vessel, thus causing fluid to be lost into the body tissues. Protein loss can lead to a fall in oncotic pressure and an inability to pull fluid back into the vascular system. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 724

What primary event has occurred when a client experiences an ectopic focus?

*The location of the heart's functioning pacemaker is no longer the sinoatrial (SA) node* Explanation: An ectopic focus results in a shift in the pacemaker of the heart from the sinoatrial node to some other site. None of the other options accurately describe the actual event associated with this shift. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 719

A client is diagnosed with a dysfunctional syncytia. What assessment finding supports this diagnosis?

*The pumping of the heart's chambers of are not properly coordinated* Explanation: Syncytia is an intertwining networks of muscle fibers that allow for a coordinated pumping contraction of the heart. Blood is normally transported away from the heart by arteries. Neither of the remaining options are related to a dysfunctional syncytia. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 714

After teaching a group of students about circulation, the instructor determines that the teaching was successful when the students identify it as:

*a high to low pressure system.* Explanation: Circulation is a high to low pressure system. Circulation is a closed system. Circulation involves a resistance and capacitance system. Circulation follows two courses, a systemic and a pulmonary courses. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 720

The nurse is caring for a client with coronary artery disease and hypertension. The nurse explains to the client that coronary artery disease disables what process that controls blood pressure?

*ability of the arterioles to increase or decrease resistance* Explanation: The entire arterial system contains muscles in the walls of the vessels all the way to the terminal branches or arterioles, which consist of fragments of muscle and endothelial cells. These muscles offer resistance to the blood that is sent pumping into the arterial system by the left ventricle, generating pressure. The arterial system is referred to as a resistance system. Its vessels can either constrict or dilate, thus increasing or decreasing resistance, respectively, based on the needs of the body. The capacitance system is the venous system and does not contribute to regulation of arterial blood pressure. Oncotic pressure acts to pull the fluid back into the vessel. The venules have no impact on regulation of arterial blood pressure. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 721

A client presents at the clinic complaining of shortness of breath, fatigue, and difficulty performing activities of daily living (ADLs). The nurse notes the bluish color around the client's mouth and fingernail beds. What condition would the nurse expect the client has?

*heart failure* Explanation: If the heart muscle fails to do its job of pumping blood through the system effectively, blood backs up and the system becomes congested. This is called heart failure (HF). In the case described, the client does not present with symptoms characteristic of a arrhythmia, hypotension, or hypertension. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 724

When explaining blood supply to the heart muscle, the nurse explains that the left circumflex artery supplies the:

*left ventricle* Explanation: Left circumflex artery supplies most of the left ventricle. The right coronary artery supplies most of the right side of the heart. The left anterior descending artery feeds the septum and anterior areas including much of the conduction system. The left anterior descending artery feeds the septum and anterior areas, including much of the conduction system. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 722

A client has developed left-sided heart failure. What assessment finding should the nurse attribute to this health problem?

*shortness of breath* Explanation: Pulmonary edema can occur when the heart is damaged and the left side of the heart is unable to effectively pump blood returning from the right side of the heart into systemic circulation. Accumulation of fluid in the lungs can cause shortness of breath. Right-sided failure is more closely associated with peripheral edema. Heart failure does not directly cause arrhythmias. Increased abdominal girth is more closely associated with fluid imbalances. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 724

What structure makes it possible for the heart to be harvested for transplantation when donated by a client who is declared "brain dead"?

*sinoatrial (SA) node* Explanation: The sinoatrial (SA) node allows the heart to beat as long as it has enough nutrients and oxygen to survive, regardless of the status of the rest of the body. This property protects the vital cardiovascular function in many disease states; it is the same property that allows the heart to continue functioning in a client who is "brain dead" allowing for the transplantation of that heart. The remaining options are related to the conduction system within the heart after the impulse has been initiated. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 715

When describing Starling's law of the heart, the instructor compares this to:

*stretching of a rubber band* Explanation: Starling's law of the heart is often compared with the stretching of a rubber band, such that the heart returns to its normal size after it is stretched—the further it is stretched, the stronger is the spring back to normal. Reference: Chapter 42: Introduction to the Cardiovascular System - Page 714

angiotensin

a peptide hormone that causes vasoconstriction and stimulates aldosterone and ADH release; part of the renin-angiotensin system

seperation of the atrium and the ventricle

atrioventricular valves

Left AV valve

bicuspid (mitral) valve

systole

contracting phase of the heart, during which blood is pumped out of the heart

ADH

released from the posterior pituitary and acts in the distal convoluted tubule of the kidney to increase water retention

diastole

resting phase of the heart; blood is returned to the heart during this phase

resistance system

the arteries; the muscles of the arteries provide resistance to the flow of blood, leading to control of blood pressure

oncotic pressure

the pulling pressure of the plasma proteins, responsible for returning fluid to the vascular system at the capillary level

peripheral, abdominal, and liver edema occur when

the right side of the heart fails.

pulse pressure

the systolic blood pressure minus the diastolic blood pressure; reflects the filling pressure of the coronary arteries

Right AV valve

tricuspid valve

veins

vessels that return blood to the heart; distensible tubes

arteries

vessels that take blood away from the heart; muscular, resistance vessels