Chapter 42: Introduction to the Cardiovascular System

Proper function of the cardiovascular system relies on blood following the correct pathway through the heart. Valves within the heart separate the organ's chambers and prevent blood from flowing in the wrong direction. What valve separates the left atrium and left ventricle?

Mitral *The mitral valve separates the left atrium and left ventricle.

The client has had a myocardial infarction. The nurse realizes the significance of this injury is damage to what layer of the heart?

myocardium *The fibers of the cardiac muscle, or myocardium, form two intertwining networks called the atrial and ventricular syncytia. A myocardial infarction impacts this layer, which results in reduced pumping ability. The endocardium is the inner lining of the heart that comes in contact with the blood. The pericardium is the sac around the heart. The epicardium is the outermost layer of the heart.

After explaining an electrocardiogram to a patient, which statement indicates that the patient understands this test?

"It will show how impulses are moving through my heart." *An electrocardiogram is a recording of the patterns of electrical impulses as they move through the heart. It is a measure of electrical activity and provides no information about the mechanical function of the heart.

As part of their orientation to a cardiac care unit, a group of recent nursing graduates is receiving a refresher in cardiac physiology from the unit educator. Which teaching point best captures a component of cardiac function?

"The diastolic phase is characterized by relaxation of ventricles and their filling with blood." *Diastole is associated with ventricular filling and relaxation. Cardiac output is not 100% or near to it with each cardiac cycle, and heart sounds are associated with valve closing. Ventricular pressure exceeds that of the aorta during systole.

A client who is on a ventilator has been declared brain dead. A family member asks the nurse how the heart can still function if the client's brain is dead. What statement is an appropriate response by the nurse?

"The heart is self-controlled and does not depend on the brain to beat." *The heart can generate action potentials on its own and can function without connection to the rest of the body. The heart will continue to function as long as oxygen and glucose are supplied to it. The brain does not initiate heart functioning. The cardiovascular center in the medulla helps to regulate blood pressure, not heart function.

After teaching a group of students about the events that occur when blood flow to the kidneys is reduced, the students demonstrate understanding when they identify that what occurs last?

Aldosterone release *When blood flow to the kidneys is reduced, the cells in the kidney release renin, which then converts angiotensinogen to angiotensin I. This is converted by angiotensin converting enzyme (ACE) to angiotensin II, which reacts with specific receptor sites on blood vessels to cause vasoconstriction. Angiotensin II also causes the release of aldosterone.

A nurse is explaining to a client the physiology of the heart with reference to the cardiac valves. Which statement by the client about the function of the cardiac valves demonstrates the correct understanding of the nurse's explanation?

Allow blood to flow in one direction only *The cardiac valves are one-way flaps of tissue that open and close in response to pressure changes within the chambers. These unidirectional valves allow blood to flow in one direction only, preventing backflow. The cardiac valves do not contract with sufficient force to pump blood; that is the function of the left ventricle. The atria heart chambers are receiving centers for blood. A complete muscular wall called the septum divides the heart into right and left sides.

A client is admitted to the cardiac unit with a diagnosis of a myocardial infarction (MI). The nurse notes that the client is having regular premature ventricular contractions (PVCs). Why would the nurse be concerned?

Blood is not efficiently pumped from the heart with PVCs. *Arrhythmias can alter cardiac output that could affect every cell in the body. Arrhythmias usually do not cause pain, disrupt healing, or interfere with the diagnosis of an MI.

A client is admitted to the cardiac unit with a diagnosis of a myocardial infarction (MI). The nurse notes that the client is having regular premature ventricular contractions (PVCs). Why would the nurse be concerned?

Blood is not efficiently pumped from the heart with PVCs. *Arrhythmias can alter cardiac output that could affect every cell in the body. Arrhythmias usually do not cause pain, disrupt healing, or interfere with the diagnosis of an MI.

When considering vital signs, which assessment is focused on the functioning of the body's resistance system

Blood pressure *The resistance system acts to control blood pressure. None of the other assessments are directly associated with the body's arteries and their influence on blood pressure.

Which property is related to the ability of the heart cells to transmit an action potential of electrical impulse?

Conductivity *Conductivity is the property of heart cells to rapidly conduct an action potential of electrical impulse.

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 *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.

The nurse assists and educates clients about blood pressure regulation. Which information is important to include in the review with clients about blood pressure?

Force exerted by the blood against the walls of the blood vessels *Blood pressure is the force exerted by the blood against the walls of the blood vessels. Cardiac output is the amount of blood the ventricles pump out in 1 minute, normally, 4 to 6 L/minute. Systolic blood pressure is the force during ventricular contraction. Diastolic blood pressure is the force during ventricular relaxation.

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

Hydrostatic pressure *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.

An electrocardiogram (ECG) is prescribed for a client experiencing signs and symptoms associated with a cardiac dysfunction. Which function of the heart will this diagnostic tool help evaluate?

Ineffective pumping *An electrocardiogram (ECG) is a measure of electrical activity. The important aspect of cardiac output—the degree to which the heart is doing its job of pumping blood out to all of the tissues is evaluated by this diagnostic tool. The remaining options related to the mechanical activity of the heart; the ECG provides no information about the mechanical activity of the heart.

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 *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.

A nurse is caring for a neonate born with a congenital heart anomaly. To better help the parents understand the impact of this disorder, the nurse begins by describing the usual flow of blood through the heart. What course should the nurse describe?

Oxygenated blood from the lungs enters the left atrium through the pulmonary veins. *Oxygenated blood from the lungs enters the left atrium through the pulmonary veins and passes through the mitral valve into the left ventricle, which contracts and ejects blood through the aortic valve into the aorta and out to the systemic circulation.

A nurse is explaining blood flow through the heart to a patient who has experienced a myocardial infarction. How would the nurse explain flow from the lungs to the heart?

Oxygenated blood from the lungs enters the left atrium through the pulmonary veins. *The left atrium receives oxygenated blood from the lungs through the pulmonary veins.

What component of the normal ECG waveform immediately precedes the contraction of the atria?

P wave *The P wave immediately precedes the contraction of the atria. The QRS complex immediately precedes the contraction of the ventricles and then relaxation of the ventricles during the T wave. The P-R interval reflects the normal delay of conduction at the AV node.

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

Pulmonary edema *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.

A client's ventricles are not contracting effectively and the problem has been determined to be at the cellular level. What component of the heart's conduction system will be evaluated first?

Purkinje fibers *The AV node then sends the impulse from the atria into the ventricles by way of the bundle of His, which enters the septum and then divides into three bundle branches. These bundle branches, which conduct the impulses through the ventricles, break into a fine network of conducting fibers called the Purkinje fibers, which deliver the impulse to the ventricular cells.

When describing cardiac conduction, the nurse explains that conduction velocity is fastest in the:

Purkinje fibers. *The conduction velocity is the slowest in the AV node and the fastest in the Purkinje fibers.

Which is released initially when blood flow to the kidneys is decreased?

Renin *When blood flow to the kidneys is reduced, the cells in the kidney release renin, which then converts angiotensinogen to angiotensin I. This is converted by angiotensin-converting enzyme to angiotensin II, which reacts with specific receptor sites on blood vessels to cause vasoconstriction. Angiotensin II also causes the release of aldosterone.

The pathway for blood flow through the heart is:

Right atria to right ventricle to pulmonary artery through lungs to pulmonary veins to left atria and then to left ventricle. *The heart has four chambers: two atria and two ventricles. The right atrium receives deoxygenated blood from the body by way of the vena cava; the right ventricle sends deoxygenated blood through the pulmonary circulation. The left atrium receives oxygenated blood from the lungs through the pulmonary veins. The left ventricle pumps oxygenated blood through the systemic circuit.

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

Right side of the heart *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.

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. *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.

It is determined that a client's cardiac rhythm is being originated in the sinoatrial (SA) node. What mechanism is responsible for the triggering of this node?

Specialized cells within the node itself *Each cycle of cardiac contraction and relaxation is controlled by impulses that arise spontaneously in the sinoatrial (SA) node of the heart. These continuous, rhythmic contractions are controlled by the heart itself; the brain does not stimulate the heart to beat. None of the other mechanisms described are involved in SA node function.

What sequence describes the flow of electrical impulses in the heart?

The Sinoatrial node, the atrioventricular node, bundle of His, right and left bundle branches, and the Purkinje fibers. *The heart contains special cells that can carry electrical impulses much more rapidly than ordinary muscle fibers. This special conduction system consists of the sinoatrial (SA) node, the atrioventricular node, bundle of His, right and left bundle branches, and Purkinje fibers. The electrical current flows over the heart in an orderly way to produce contraction of both atria, then both ventricles.

A client has severe aortic valve disease. When educating the client about anatomy, what would the nurse include?

The aortic valve separates the left ventricle and aorta. *Heart valves function to maintain the one-way flow of blood and prevent backflow. The mitral valve separates the left atrium and left ventricle. 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.

A client has been declared "brain dead". The family asks the nurse to explain why their loved one's heart continues to beat in spite of the damage to the brain. The nurse should provide what explanation to the family?

The heart beats in response to impulses that are generated by specialized cells located in the heart not the brain. *Each cycle of cardiac contraction and relaxation is controlled by impulses that arise spontaneously in certain pacemaker cells of the sinoatrial (SA) node of the heart. This property allows the heart to continue functioning in a patient who is "brain dead." None of the other options accurately describe the relationship between "brain death" and cardiac functioning.

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 *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.

A client has been diagnosed with a problem associated with the heart's right atrium. Which statement indicates the client

The top chamber, responsible for receiving blood from my body's veins, is the problem. *An atrium is a top chamber of the heart that receives unoxygenated blood from veins. The left atrium is larger in size than the right atrium.

The nurse is reviewing with the client the three major layers of the heart wall and how they relate to the pericardium. What is the best description by the nurse to the client about the myocardium layer of the heart?

Thick, strong muscles making up the middle layer *Thick, strong muscles making up the middle layer is known as the myocardium. The thin outer layer of the cardiac wall is known as the epicardium. The endocardium is a membrane lining the heart's interior wall. The pericardium is the outermost layer anchoring the heart.

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. *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.

The nurse is caring for a client with severe coronary artery disease (CAD) who is experiencing chest pain because the oxygen demand exceeds supply. What forces could potentially be lowered to reduce oxygen consumption? Select all that apply.

afterload stretch on the ventricles heart rate preload

The nurse is caring for an older adult client who is displaying alterations in the conduction of impulses in the SA node. What assessment finding is most likely?

cardiac arrhythmias *Alterations in the generation of conduction of impulses in the heart cause arrhythmias (arrhythmias), which can upset the normal balance in the cardiovascular system and lead to a decrease in cardiac output, affecting all of the cells of the body. Tachycardia is only one of the possible arrhythmias that may result. Cardiac gallop and murmurs in the older adult with no history of congenital anomalies is usually caused by a poorly functioning heart valve and not by an alteration in conduction.

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

left ventricle. *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.

A group of nursing students is preparing a poster presentation describing the anatomy and function of the heart. In their diagram of the organ, they label the structure that separates the left and right sides of the heart as the:

septum *The septum is a muscular wall that separates the right and left sides of the heart.

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 *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.

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

stretching of a rubber band *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.