ch 17 circulatory function
Which statement most accurately captures a principle of blood flow? a. With constant pressure, a small increase in vessel radius results in an exponential increase in blood flow. b. Blood flows most quickly in the small-diameter peripheral capillaries. c. Blood flow is primarily determined by blood viscosity and temperature. d. Smaller cross-sectional vessel area is associated with lower flow velocity.
a Doubling the radius of a vessel is associated with a fourth-power increase in flow, as long as pressure remains constant. Blood flow is primarily a function of blood pressure, resistance, and viscosity. The small size of capillaries is associated with quite slow velocity, given their large total combined cross-sectional area. Smaller cross-sectional area is associated with greater velocity.
Which dysrhythmia is considered to be the most fatal and requires immediate treatment? a. Ventricular fibrillation b. Atrial flutter c. Premature ventricular contractions d. Premature atrial contractions
a Ventricular fibrillation represents severe derangements of cardiac rhythms that terminate fatally within minutes unless corrective measures are taken promptly. All of the other dysrhythmias need to have further investigation into etiology, but are not immediately fatal.
The circulatory system can be divided into two parts. What does the systemic circulation include? Select all that apply. a. Capillaries b. Right heart c. Pulmonary artery d. Aorta
a, d The systemic circulation includes the aorta and capillaries. The pulmonary circulation includes the right heart and pulmonary artery.
Valves in the veins prevent retrograde flow. In which veins are there no valves? Select all that apply. a. Abdominal b. Femoral c. Carotid d. Thoracic
a, d There are no valves in the abdominal or thoracic veins. Therefore, pressure in the abdominal and thoracic cavities heavily influence blood flow in these veins.
A nurse is caring for four clients with the diagnosis of atrial fibrillation. Which client will likely require cardioversion related to complications? a. Client admitted with blood clots in the lungs from undiagnosed atrial fibrillation b. Newly diagnosed client with atrial fibrillation and has developed pulmonary edema c. Client experiencing bleeding related to anticoagulants prescribed for the atrial fibrillation d. Client who fainted because of a very low pulse rate due to an antiarrhythmic medication
b Cardioversion may be considered in clients with atrial fibrillation, particularly when pulmonary edema and unstable cardiac status is present. cardioverson = sending electrical hots to your heart through electrodes placed on your chest The other clients have a complication related to lack of diagnosis or adverse reactions to prescribed treatments.
The cardiologist just informed a client that he has a reentry circuit in the electrical conduction system in his heart. This dysrhythmia is called Wolff-Parkinson-White (WPW) syndrome. After the physician has left the room, the client asks the nurse to explain this. Which statement most-accurately describes what is happening? a "For some reason, your electrical system is not on full charge so they will have to put in new leads and a pacemaker to make it work better." b. "There is an extra, abnormal electrical pathway in the heart that leads to impulses traveling around the heart very quickly, in a circular pattern, causing the heart to beat too fast." c. "This means that the SA node (which is the beginning of your heart's electrical system) has been damaged and is no longer functioning normal." d. "You must have a large clot in one of your arteries that supply oxygenated blood to the special conduction cells in your heart."
b There are several forms of reentry. The first is anatomic reentry. It involves an anatomic obstacle around which the circulating current must pass and results in an excitation wave that travels in a set pathway. Dysrhythmias that arise as a result of anatomic reentry are paroxysmal supraventricular tachycardias, as seen in WPW syndrome, atrial fibrillation, atrial flutter, etc. Sinus node dysrhythmias and sick sinus syndrome result in the SA node being damaged. A large clot in one of the arteries can result in dysrhythmias caused by MI. A third-degree block or ventricular standstill, for example, would result in new leads and a pacemaker for this client.
While intubated for surgery, a client has inadvertently had his vagus nerve stimulated. What effect would the surgical team expect to observe? a. Decreased heart rate as a result of impaired acetylcholine reuptake b. Decreased heart rate as a result of parasympathetic innervation of the heart c. Decreased vascular perfusion due to parasympathetic stimulation d. Decreased heart rate, contractility, and afterload
b Vagal stimulation results in a 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.
Downstream peripheral pulses have a higher pulse pressure because the pressure wave travels faster than the blood itself. What occurs in peripheral arterial disease? a. Downstream peripheral pulses are increased even more than normal. b. The pulse decreases, rather than increases, in amplitude. c. Downstream peripheral pulses are greater than upstream pulses. d. The reflected wave is transmitted more rapidly through the aorta.
b With peripheral arterial disease, there is a delay in the transmission of the reflected wave so that the pulse decreases, rather than increases, in amplitude.
A client is lying in a recumbent position. In this client, approximately how much total blood volume is in the central circulation? a. 15% - 20% b. 25% - 30% c. 20% - 25% d. 30% - 35%
b in the recumbent position, approximately 25 to 30 percent of the total blood volume is in the central circulation.
A nursing student is studying the properties of cardiac rhythm to better understand what causes dysrhythmias to occur. The student begins to understand that there is a programmed ability for certain cells to conduct impulses. Interruption in this ability can result in abnormalities of cardiac rate and rhythm; this property would be: a. refractoriness. b. conductivity. c. excitability. d. automaticity.
b. There are 4 properties of cardiac conduction and they are... -automaticity- the ability to initiate an electric impulse -excitability- the ability to respond to an impulse - conductivity- the ability to move that impulse along the pathway - refractoriness- which limits the ability to respond to stimuli. In this question the most accurate response is conductivity.
A client has prominent jugular veins. What type of medical problem is associated with prominent jugular veins? a. Left-sided heart failure b. Cerebrovascular accident (stroke) c. Right-sided heart failure d. Shock
c Right-sided heart failure is seen with prominent jugular veins.
Which of the following is true regarding pulmonary circulation? a. It consists of the left side of the heart, the aorta, and its branches. b. It is the larger of the two circulatory systems. c.. It is a low-pressure system that allows for improved gas exchange. d. The system functions with an increased arterial pressure to circulate through the distal parts of the body.
c The pulmonary circulation consists of the right heart and the pulmonary artery, capillaries, and veins. It is the smaller of the systems and functions at a lower pressure to assist with gas exchange.
The semilunar valves of the heart open at the onset of the ejection period. Approximately what percentage of the stroke volume is ejected during the first quarter of systole? a. 70% b. 50% c. 40% d. 60%
d Approximately 60 percent of the stroke volume is ejected during the first quarter of systole.
The nurse is teaching a client diagnosed with heart failure about preload. Which principle would be most appropriate to provide to the client? a. Preload determines the frequency by which the ventricles contract and blood is ejected. b. Preload is the ability of the heart to change its force of contraction. c. Preload is the pressure or tension work of the heart. d. Preload represents the volume work of the heart.
d Preload is the distending force that stretches the heart muscle just prior to work of the onset of ventricular contraction. It represents the volume of blood stretching the ventricular muscle fibers at end of diastole (i.e., end-diastolic volume) and is the sum of the blood remaining in the heart at the end of systole (end-systolic volume) and the venous return to the heart. The pressure or tension work of the heart refers to afterload. The ability of the heart to change its force of contraction refers to cardiac contractility. The frequency by which the ventricles contract and blood is ejected refers to heart rate.
A client has a blood pressure of 68/38 mm Hg and fainted after donating a unit of blood. The client is experiencing low preload from loss of blood volume. What is preload? a. Blood pumped by each ventricle in 1 minute b. Venous return to the heart c. Resistance to ventricular emptying d. Blood ejected from each ventricle with each contraction
b Preload is the amount of venous return to the heart. Afterload is the pressure in which the muscle exerts its contractile force in order to move blood into the aorta. Contractility is the ability of the heart to change its force of contraction without changing its resting length.
Which factor represents the amount of blood that the heart must pump with each beat and is determined by the stretch of the cardiac muscle fibers and the actions of the heart prior to cardiac contraction? a. Preload b. Heart rate c. Afterload d. Cardiac contractility
a Preload is the distending force that stretches the heart muscle just prior to the work of the onset of ventricular contraction. It represents the volume of blood stretching the ventricular muscle fibers at the end of diastole (i.e., end-diastolic volume) and is the sum of the blood remaining in the heart at the end of systole (end-systolic volume) and the venous return to the heart.
A group of nursing students is discussing ventricular dysrhythmias and one student is unsure why a client with frequent premature ventricular complexes (PVCs) has an irregular radial pulse. One of the other students explains that premature ventricular complexes often do not produce a palpable pulse due to: a. decreased ventricular filling time. b. weakness of the ventricle. c. ventricular compensatory pause. d. recurrent ventricular pathways.
a Premature ventricular complexes cause a decrease in ventricular filling time. They are caused by ectopic foci in the ventricles, often causing a delay in ventricular repolarization. This delay is caused by the inability of the ventricles to respond to the next impulse from the SA node, causing an irregular rhythm. Insufficient diastolic filling time during the premature ventricular complex causes a decrease in the blood being ejected from the ventricles, often without a palpable pulse.
A nurse working with a client in heart failure is explaining why the symptoms of the heart failure were not evident for a long period of time. When describing the Frank-Starling mechanism, the nurse will explain: a. the relationship between venous return and stroke volume. b. the molecular structure of actin and myosin and their effect on contraction. c. the high oxygenation needs of cardiac muscle and the role of coronary circulation. d. the physiologic function of chemoreceptors and baroreceptors.
a The Frank-Starling principle addresses the relationship between venous return and stroke volume. It does not directly address the characteristics of actin and myosin. The principle is unrelated to coronary circulation, chemoreceptors and baroreceptors.
When reviewing diagnostic test results and physical assessment data for a client with a history of stage II hypertension, which of the following would be of most concern to the nurse? a. An ejection fraction of 40% b. Blood pressure of 146/80 c. Point of maximum impulse is located midclavicular at the 5th intercostal space d. A heart rate (HR) of 62 beats/minute
a This ejection fraction is below normal (normal is about 55% to 75%) and indicates a poor prognosis. This low ejection fraction is a result of the complications of long-standing hypertension.
The heart is a four-chambered muscular pump. In one day, how many gallons of blood are pumped throughout the body? a. 1800 b. 1600 c. 1700 d. 1500
a. In one day, this pump moves more than 1800 gallons of blood throughout the body.
The linear velocity of blood flow in the circulatory system varies widely. What is the linear velocity in the aorta? a. 30 to 35 cm/second b. 40 to 45 cm/second c. 20 to 25 cm/second d. 50 to 55 cm/second
a. The linear velocity of blood flow in the circulatory system varies from 30 to 35 cm/second in the aorta.
Which client on the nurse's team will be given priority for cardiac monitoring based on medical history? a. Adult client who had a pacemaker implanted 5 years ago admitted with chronic obstructive pulmonary disorder (COPD) b. Adolescent client resuscitated following drowning in a swimming pool that required CPR at the scene c. Postoperative client who has a history of diabetes for the last 10 years d. Older adult client admitted with pneumonia for a few days of IV antibiotics
b Examples of clients categorized as class I are those who have been resuscitated from a cardiac arrest, are in the early phase of acute coronary syndrome, have unstable coronary syndromes or newly diagnosed high-risk coronary lesions, or have had recent cardiac surgery. Given these guidelines, the adolescent client who was resuscitated by CPR at the pool is the priority of this group of clients. A client with diabetes is at risk for coronary disease but this client underwent surgery without mention of cardiac abnormalities, which places the client at a lower priority for a monitor. The client with COPD is not the priority for monitoring, even though the client has a pacemaker. An older adult client needing IV antibiotics is also a lower priority for continuous monitoring of cardiac rhythm.
The physician states that a client has adequate collateral circulation. The nurse interprets this as: a. Anastomosis of the arterial and venous circulation b. Long-term compensatory regulation of blood flow c. Establishment of compensatory lymphatic drainage d. Development of increased collagen
b Collateral circulation is a mechanism for the long-term regulation of local blood flow. In the heart and other vital structures, anastomotic channels exist between some of the smaller arteries. These channels permit perfusion of an area by more than one artery. When one artery becomes occluded, these anastomotic channels increase in size, allowing blood from a patent artery to perfuse the area supplied by the occluded vessel. Lymph node removal requires establishment of compensatory lymphatic drainage. The aging process produces the development of increased collagen.
In the ICU, the nurse hears an emergency cardiac monitor go off. The nurse looks at the telemetry and notices the client has gone into ventricular tachycardia. The nurse will likely assess for signs/symptoms of: a. oxygen deprivation with O2 saturation decreasing to ~90%. b. decreasing cardiac output due to less ventricular filling time. c. development of hypertension with BP 190/98. d. increasing cardiac index by correlating the volume of blood pumped by the heart with an individual's body surface area.
b One of the dangers of ventricular tachycardia is a reduction in cardiac output because the heart does not have time to fill adequately.
A client with heart disease has the left ventricular ejection fraction measured. What is the normal left ventricular ejection when determined by angiocardiography? a. 65% - 85% b. 55% - 75% c. 45% - 65% d. 35% - 55%
b The normal left ventricular ejection fraction is usually 55 percent to 75 percent when determined by angiocardiography.
A physician has ordered the measurement of a cardiac client's electrolyte levels as part of the client's morning blood work. Which statement best captures the importance of potassium in the normal electrical function of the client's heart? a. The impermeability of cardiac cell membranes to potassium allows for action potentials achieved by the flow of sodium ions. b. Potassium is central to establishing and maintaining the resting membrane potential of cardiac muscle cells. c. The reciprocal movement of one potassium ion for one sodium ion across the cell membrane results in the production of an action potential. d. Potassium catalyzes the metabolism of ATP, producing the gradient that results in electrical stimulation.
b The selective permeability of cell membranes to potassium, and its near-impermeability to sodium ions, produces the resting membrane potential of cardiac cells. Potassium does not catalyze the metabolism of ATP, and sodium and potassium ions do not move across the cell membrane in a 1:1 ratio.f
A client has been diagnosed with runs of intermittent ventricular tachycardia where the client loses consciousness and needs to be stimulated to recovery. Knowing this history, the nurse will educate the client about which treatment intervention/procedure that will depolarize the heart to allow the sinoatrial node to regain control of the heart? a. The benefits of anti-arrhythmic drugs and possible side effects b. Immediate pacemaker implantation c. Education involving automatic implantable cardioverter-defibrillators implantation d. The benefits of ablation therapy bi-monthly
c Automatic implantable cardioverter-defibrillators are used to treat people with life threatening ventricular tachyarrhythmias by the use of intrathoracic electrical countershock. A cardiac pacemaker is an electronic device that delivers an electrical stimulus to the heart. It is beneficial for those with atrioventricular heart block, symptomatic bradycardia, and other cardiac arrhythmias. Leads are placed in the atria, ventricles or both. Drugs may help control heart rhythms, but they cannot stop ventricular tachycardia unless given intravenously in an intensive care setting. Ablation therapy is used to treat recurrent, life-threatening supraventricular and ventricular tacyarrhythmias. Ablation therapy is performed by catheter or surgical techniques and involves localized destruction, isolation, or excision of cardiac tissue.
An 80-year-old male client arrives for his yearly physical without any complaints, and following the checkup the physician explains that he has noted atrial fibrillation (AF) on the client's ECG. Before the physician can explain the disorder, the client becomes very upset and states he thinks he is going to die. The physician explains that atrial fibrillation involves the top chambers of the heart and that: a. the client will experience severe palpitations. b. the client will be placed on anticoagulants immediately. c. many people live with atrial fibrillation without even knowing they have it. d. atrial fibrillation is a disorganized ventricular rhythm with recurrent circuits.
c Many people live with atrial dysrhythmias, including atrial fibrillation, without knowing the dysrhythmia exists. Atrial dysrhythmias are typically less serious because they do not impact the ability of the ventricles to pump. This client is at high risk to develop atrial fibrillation due to his advanced age; the rates of atrial fibrillation begin to increase over the age of 60 and males have a greater prevalence. It is true that atrial fibrillation is a disorganized rhythm; however it is not ventricular. The client may or may not need anticoagulation; there are other considerations to be made before these medications would be considered.
There are three main atrial pressure waves that occur during the cardiac cycle. Which wave occurs during the last part of diastole and is caused by atrial contraction? a. c b. b c. v d. a
d a wave-- occurs during the last part of diastole and is caused by atrial contraction. c-- waveoccurs as the ventricles begin to contract, and their increased pressure causes the AV valves to bulge into the atria. v wave-- occurs toward the end of systole when the AV valves are still closed and results from a slow buildup of blood in the atria.
A 71-year-old man is slated for pacemaker insertion for treatment of a third-degree AV block. The man's nurse has been educating him around his diagnosis and treatment and answering the numerous questions he has about his health problem. Which teaching point should the nurse include in this client teaching? a. "Because the normal electrical communication is lacking, the bottom parts of your heart are beating especially fast to compensate for inefficiency." b. "This is almost certainly a condition that you were actually born with, but that is just now becoming a serious problem." c. "If left untreated, this would have put you at great risk for stroke or heart attack." d. "The root problem is that the top chambers of your heart and the bottom chambers of your heart aren't coordinating to pump blood efficiently."
d A third-degree AV block is characterized by independent, and thus uncoordinated, pacemaker action for the atria and for the ventricles. It can be either congenital or acquired, and ventricular contraction tends to be slow, not fast. Manifestations tend to be those associated with decreased cardiac output it is not necessarily associated with a large increase in stroke or MI risk.
Which statement describes phase 4 of the action potential of cells in the sinoatrial (SA) node? a. The fast sodium channels in the cellular membranes close, causing an abrupt decrease in intracellular positivity. b. The cells are capable of responding to a greater-than-normal stimulus before the resting membrane potential is reached. c. Potassium permeability is allowing the cell membrane to remain depolarized and the Ca++ channel opens, moving Ca++ back into the cell. d. a slow depolarization occurs when Na+ is transported out of the cell and K+ moves back in, resulting in resting membrane potential.
d During phase 4 in the cells of the SA node, a slow leakage of current through the slow channels of the cellular membrane leads to spontaneous depolarization; this slow response enables pacemaker function. The cells responding to greater-than-normal stimulus describes the relative refractory period of the action potential curve, which occurs at the end of phase 3 in cardiac cells. The fast sodium channels in the cellular membranes closing describes phase 1 of the action potential, which signals the end of depolarization. The sodium-potassium pump transports sodium out of the cell, and a smaller amount of potassium into it, contributing to the negative intracellular charge of the resting membrane potential in phase 4.
A 72-year-old female has been told by her physician that she has a new heart murmur that requires her to go visit a cardiologist. Upon examination, the cardiologist informs the client that she has aortic stenosis. After the cardiologist has left the room, the client asks, "What caused this [aortic stenosis] to happen now?" The clinic nurse responds: a. "Aortic stenosis is commonly seen in older adult clients. Basically, there is a blockage in the valve that is causing blood to pool, causing decreased velocity of flow." b. "This is caused by a tear in one of the papillary muscles attached to the valve. They can do a procedure where they thread a catheter into the heart and reattach the muscle ends." c. Because of the high amount of energy it takes to push blood through the aortic valve to the body, your valve just had to work too hard and it is weakening. d. "Heart murmurs result from tumultuous flow through a diseased heart valve that is too narrow and stiff. This flow causes a vibration called a murmur."
d Heart murmur results from turbulent flow through a diseased heart valve that may be narrow, too stiff, or too floppy. This turbulent flow causes a vibration called a murmur.
Humoral control of blood flow involves the effect of vasodilator and vasoconstrictor substances in the blood. Select the factor that has a powerful vasodilator effect on arterioles and increases capillary permeability. a. Norepinephrine b. Prostaglandins c. Serotonin d. Histamine
d Histamine has a powerful vasodilator effect on arterioles and has the ability to increase capillary permeability, allowing leakage of both fluid and plasma proteins into the tissues. Norepinephrine is a powerful vasoconstrictor. Serotonin causes vasoconstriction and plays a major role in control of bleeding. Prostaglandins produce either vasoconstriction or vasodilation.
The troponin complex is one of a number of important proteins that regulate actin-myosin binding. Troponin works in striated muscle to help regulate calcium-mediated contraction of the muscle. Which of the troponin complexes is diagnostic of a myocardial infarction? a. Troponin A and troponin I b. Troponin C and troponin T c. Troponin A and troponin C d. Troponin T and troponin I
d In clinical practice, the measurement of the cardiac forms of troponin T and troponin I is used in the diagnosis of myocardial infarction. Troponin C is not diagnostic of a myocardial infarction. Troponin A is not one of the troponin complexes.
A client is experiencing impaired circulation secondary to increased systemic arterial pressure. Which statement is the most relevant phenomenon? a. Systolic impairment because of arterial stenosis b. Increased preload due to vascular resistance c. Impaired contractility due to aortic resistance d. High afterload because of backpressure against the left ventricle
d Increased pressure in the aorta and other arteries constitutes a greater amount of afterload work. This situation is not indicative of increased preload or impaired contractility. Systolic impairment is not a recognized characterization of inadequate cardiac performance.
A client says that when the hospital checked his blood pressure after he lost a lot of blood in a work-related accident, the top number (systolic pressure) was lower than usual but the bottom number (diastolic pressure) was about the same. Why is this? a. The heart rate increased with blood loss. b. The stroke volume increased with blood loss. c. Systemic vasodilation maintained the diastolic pressure. d. Systemic vasoconstriction maintained the diastolic pressure.
d Systemic vasoconstriction, not vasodilation, would maintain the diastolic pressure. The stroke volume and heart would not affect the diastolic pressure with blood loss.
A nurse is teaching a client the correct technique for taking an arterial pulse. The nurse explains that the pulsations are: a. Turbulence of the blood flow b. Korotkoff sounds c. Blood flow in the veins d. Pressure pulses
d The arterial pressure pulse represents the energy that is transmitted from molecule to molecule along the length of the vessel. When taking a pulse, it is the pressure pulses that are felt. Pressure pulses have no direct relation to the blood flow. It is the pressure pulses that produce the Korotkoff sounds heard during blood pressure measurement. Pressure pulses would be felt even if there was no blood flow at all.
The school nurse is doing a health class on the functional organization of the circulatory system. What is the function of the capillaries in the circulatory system? a. Pump blood b. Collect deoxygenated blood from the tissues c. Distribute oxygenated blood to the tissues d. Exchange gases, nutrients, and wastes
d The circulatory system consists of the heart, which pumps blood; the arterial system, which distributes oxygenated blood to the tissues; the venous system, which collects deoxygenated blood from the tissues and returns it to the heart; and the capillaries, where exchange of gases, nutrients, and waste takes place.
The lymph system correlates with the vascular system without actually being a part of the vascular system. Among other things, the lymph system is the main route for the absorption of fats from the gastrointestinal system. The lymph system empties into the right and left thoracic ducts, which are the points of juncture with the vascular system. What are these points of juncture? a. The internal and external jugular veins b. The bifurcation of the common carotid arteries c. The junction of the subclavian and the pulmonary veins d. Junctions of the subclavian and internal jugular veins
d The lymph capillaries drain into larger lymph vessels that ultimately empty into the right and left thoracic ducts. The thoracic ducts empty into the circulation at the junctions of the subclavian and internal jugular veins. The lymphatic system only joins the vascular system in one place, so no other answer is accurate.
Which neurotransmitter is associated with the parasympathetic nervous system? a. Norepinephrine b. Epinephrine c. Dopamine d. Acetylcholine
d. The actions of the autonomic nervous system are mediated by chemical neurotransmitters. Acetylcholine is the postganglionic neurotransmitter for parasympathetic neurons norepinephrine is the main neurotransmitter for postganglionic sympathetic neurons. Sympathetic neurons also respond to epinephrine, which is released into the bloodstream by the adrenal medulla. dopamine can also act as a neurotransmitter for some sympathetic neurons.
