chapter 18-the cardiovascular system: the heart
Which portion of the electrocardiogram represents the wave-like change in charge in the positive direction received by the atria from the sinoatrial (SA) node? S-T segment QRS complex P wave T wave
P wave
In a patient with an incompetent aortic valve, the nurse expects the patient to show signs and symptoms of which of the following? Peripheral congestion. Hepatic congestion. Cerebral congestion. Pulmonary congestion.
Pulmonary congestion.
Which portion of the electrocardiogram represents the time during which the ventricles are in systole? P wave T wave Q-T interval QRS complex
Q-T interval
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart? AV bundle (bundle of His) SA node AV node Purkinje fibers
SA node
Although Dr. El-Sheikh has a high systolic blood pressure, her heart rate is also high. This is most likely due to: Parasympathetic activation. Excessive vagus nerve firing. The Bainbridge reflex, caused by increased atrial filling. Sympathetic stimulation.
Sympathetic stimulation.
Name the irregular ridges of muscle lining the ventricles. Pectinate muscles Chordae tendineae Trabeculae carneae Papillary muscles
Trabeculae carneae
Identify the valve found between the left atrium and left ventricle. Bicuspid (mitral) valve Aortic valve Tricuspid valve Pulmonary valve
Bicuspid (mitral) valve
The normal heart sounds are S1 and S2. When do you predict you would hear Caleb's abnormal heart sound? between S1 and S2 after S2 before S1 during S2
between S1 and S2
An abnormal P wave could be indicative of ______. an abnormal AV node an abnormal AV bundle incomplete ventricular repolarization enlarged atria
enlarged atria
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane? fast calcium fast sodium potassium slow calcium
fast calcium
Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane? desmosomes gap junctions tight junctions intercalated discs
gap junctions
How would an increase in the sympathetic nervous system increase stroke volume? increased end diastolic volume decreased end diastolic volume increased contractility increased end systolic volume
increased contractility
By what mechanism would an increase in venous return increase stroke volume? increased end systolic volume increased contractility decreased end diastolic volume increased end diastolic volume
increased end diastolic volume
Which of the following would increase cardiac output to the greatest extent? decreased heart rate and decreased stroke volume increased heart rate and decreased stroke volume increased heart rate and increased stroke volume decreased heart rate and increased stroke volume
increased heart rate and increased stroke volume
Which heart chamber receives blood from the pulmonary veins? right ventricle left ventricle right atrium left atrium
left atrium
Which chamber pumps oxygenated blood out the aorta to the systemic circuit? right ventricle right atrium left atrium left ventricle
left ventricle
Which term describes the abnormal sounds produced by Caleb's heart? View Available Hint(s) systole conduction murmur diastole
murmur
Which layer of the heart wall contracts and is composed primarily of cardiac muscle tissue? endocardium visceral layer of the serous pericardium epicardium myocardium
myocardium
What separates the parietal and visceral pericardium? pericardial cavity fibrous pericardium epicardium myocardium
pericardial cavity
Which of these vessels returns blood to the left atrium of the heart? pulmonary trunk pulmonary veins coronary sinus superior vena cava
pulmonary veins
In an ischemic heart, the affected cardiac muscle cells are likely to have an altered ______. number of Z discs number of desmosomes number of slow Ca+2 channels resting membrane potential
resting membrane potential
Into which chamber of the heart do the superior vena cava, inferior vena cava, and coronary sinus return deoxygenated blood? left ventricle right atrium left atrium right ventricle
right atrium
Which heart chamber pumps unoxygenated blood out the pulmonary trunk? left atrium right atrium right ventricle left ventricle
right ventricle
In order to cause cardiac muscle contraction, the contractile cells must also depolarize. What causes the depolarization of the contractile cells? the flow of negative ions from adjacent cells the flow of positive ions from adjacent cells an unstable resting membrane potential in the contractile cells
the flow of positive ions from adjacent cells
Ventricular pressure is greater than aortic pressure during which phase of the cardiac cycle? isovolumetric relaxation isovolumetric contraction ventricular ejection ventricular filling
ventricular ejection
Most of the decrease in ventricular volume takes place during which phase of the cardiac cycle? atrial contraction ventricular filling isovolumetric relaxation ventricular ejection
ventricular ejection (As the ventricles contract, blood is forced through the semilunar valves and out into the arteries, resulting in a reduction in ventricular blood volume. At the end of this phase, ventricular volume is at a minimum−the "end-systolic volume" (ESV).)
At what point in the cardiac cycle does the AV valve open? when ventricular pressure becomes greater than aortic pressure when the semilunar valve closes when aortic pressure becomes greater than ventricular pressure when atrial pressure becomes greater than ventricular pressure
when atrial pressure becomes greater than ventricular pressure
Which of the following cannot trigger tachycardia? cardiovascular center increased sympathetic stimulation increased vagal tone increased venous return
increased vagal tone
Which of the following is true during ventricular systole? The ventricles are empty. The ventricles are relaxed. The AV valves are closed. The atria are in systole.
The AV valves are closed. (At the beginning of ventricular systole, the one-way AV valves are forced shut. The AV valves remain shut throughout ventricular systole. This prevents blood from flowing back into the atria when the ventricles contract.)
Which of the following is equivalent to the ventricular volume during isovolumetric contraction? The end diastolic volume (EDV) the end systolic volume (ESV) the minimum ventricular volume (MVV) the stroke volume (SV)
The end diastolic volume (EDV)
Isovolumetric relaxation is characterized by which of the following? Pressure in the ventricle exceeds pressure in the aorta. The semilunar and AV valves are closed. Blood flows backward through the heart from high to low pressure. Pressure in the atrium exceeds pressure in the ventricle.
The semilunar and AV valves are closed.
During the ventricular ejection phase of the cardiac cycle, which of the following is true? The atria are in systole. The semilunar valves are open. The AV valves are open. The ventricles are in diastole.
The semilunar valves are open. (During ventricular ejection, blood flows from the ventricles into the arteries. )
When the atria contract, which of the following is true? The ventricles are in diastole. The atria are in diastole. The semilunar valves are open. The AV valves are closed.
The ventricles are in diastole.
Increased pressure in the ventricles would close what valve(s)? semilunar valves only AV valves only both semilunar and AV valves
AV valves only
Identify the ear like flaps that are attached to the top chambers of the heart. Pectinate muscles Coronary sinus Auricle Atrium
Auricle
Which of the following can be heard with a stethoscope most easily? Isovolumetric contraction Contraction of atria Closing of atrioventricular valves Blood flow into aorta
Closing of atrioventricular valves (The first heart sound, often described as a lubb, corresponds to the closing of the atrioventricular valves. The second heart sound is a sharper and crisper dupp that corresponds to the closing of the semilunar valves. )
Name the inner lining of the heart. Pericardium Epicardium Myocardium Endocardium
Endocardium
The base of the heart is located at the bottom of the heart. True False
False
Why are gap junctions a vital part of the intercellular connection of cardiac muscles? Gap junctions form strong intercellular connections. Gap junctions contract when stimulated, strengthening the force of cardiac cell contraction. Gap junctions allow action potentials to spread to connected cells. Gap junctions allow calcium to enter the cell, triggering calcium release from the SR.
Gap junctions allow action potentials to spread to connected cells.
Identify the most muscular chamber. Left atrium Right ventricle Right atrium Left ventricle
Left ventricle
Which of the following is correct about the filling of the ventricles? The majority of ventricular filling is caused by contraction of the atria. Most blood flows passively into the ventricles through open AV valves.
Most blood flows passively into the ventricles through open AV valves.
Which statement regarding cardiac muscle structure is accurate? Cardiac cells possess fewer mitochondria than other types of muscle cells. Cardiac muscle cells are independent of one another both structurally and functionally. Cardiac cells are long, cylindrical, and multinucleate. Myofibrils of cardiac muscle tissue vary in diameter and branch extensively.
Myofibrils of cardiac muscle tissue vary in diameter and branch extensively.
Contraction of the atria results from which wave of depolarization on the ECG tracing? QRS complex P wave T wave
P Wave
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves. View Available Hint(s) Pressure in the ventricles would be greater than in the atria. Pressures in the atria and ventricles would be equal. Pressure in the atria would be greater than the pressure in the ventricles.
Pressure in the atria would be greater than the pressure in the ventricles.
What is the function of the coronary circulation? Provide a blood supply to the heart Provide a blood supply to the pericardium Provide a blood supply to the aortic arch Provide a blood supply to the lungs
Provide a blood supply to the heart
Blood enters the left and right coronary arteries directly from which vessel or chamber? left ventricle aorta circumflex artery pulmonary trunk
aorta
Heart murmurs caused by a stenotic mitral valve ______. are heard as a high pitched click when the valve should be—but is not—wide open during systole. are detected due to the turbulent blood flow that occurs as blood backflows into the left atrium are detected if the valve's cusps are thin and flexible All of the listed responses are true.
are heard as a high pitched click when the valve should be—but is not—wide open during systole.
Atrial pressure is greater than ventricular pressure during which phase of the cardiac cycle? isovolumetric relaxation isovolumetric contraction ventricular ejection atrial contraction
atrial contraction
How would a decrease in blood volume affect both stroke volume and cardiac output? decreased stroke volume and no change in cardiac output increased stroke volume and increased cardiac output no change in stroke volume and decreased cardiac output decreased stroke volume and decreased cardiac output
decreased stroke volume and no change in cardiac output ( a decreased blood volume would decrease the end diastolic volume, thus lowering the stroke volume. Although this would initially lead to a decrease in the cardiac output, heart rate would increase because of increased activity of the sympathetic nervous system in an effort to maintain cardiac output.)
Which of the following would cause a DECREASE in cardiac output (CO)? heightened use of skeletal muscle an increase in adrenal medulla output (epinephrine) decreasing thyroid function (thyroxine) suddenly standing up from a supine position
decreasing thyroid function (thyroxine)
What does the ECG wave tracing represent? electrical activity in the heart contraction of the heart
electrical activity in the heart
Which of the following is equivalent to the ventricular volume during isovolumetric relaxation? stroke volume (SV) end systolic volume (ESV) end diastolic volume (EDV) maximum ventricular volume (MVV)
end systolic volume (ESV) (Isovolumetric relaxation occurs at the beginning of ventricular diastole when the ventricular volume is at its minimum value−the end systolic volume (ESV). Because no volume changes occur during isovolumetric relaxation, ventricular volume remains at this value throughout the phase.)
Which of the following is the innermost layer of the heart? epicardium parietal layer visceral layer endocardium
endocardium
Which of the following would increase heart rate? acetylcholine epinephrine and norepinephrine increased activity of the parasympathetic nervous system decreased activity of the sympathetic nervous system
epinephrine and norepinephrine
Which of the following INCREASES stroke volume? decrease in end diastolic volume (EDV) decrease in preload exercise severe blood loss
exercise
What is the period during the cardiac cycle when the valves leading to and from the ventricles are completely closed and blood volume in the ventricles remains constant as the walls contract? isovolumetric contraction phase ventricular ejection ventricular filling isovolumetric relaxation phase
isovolumetric contraction phase
Which of these muscles is particularly associated with anchoring the right and left atrioventricular valves? pectinate muscles myocardium trabeculae carneae papillary muscles
papillary muscles
During which of these stages are the aortic and pulmonary valves open? phase 1 phase 2a phase 2b phase 3
phase 2b (During phase 2b, the pressure in the ventricles exceeds that of the aorta and pulmonary trunk, so their valves open and allow blood to be ejected.)
Which of the following is a branch of the right coronary artery? circumflex artery coronary sinus anterior interventricular artery posterior interventricular artery
posterior interventricular artery
One of the changes that occurs in the pacemaker potential (unstable resting membrane potential) in the SA node (an autorhythmic cell) is a decreased efflux of what ion? potassium calcium sodium
potassium
Cardiac tamponade results in ineffective pumping of blood by the heart. This is because the excessive amount of fluid in the pericardial cavity will ______. prevent the visceral layer of the serous pericardium from properly surrounding the heart prevent the heart from filling properly with blood prevent proper oxygenation of the blood interfere with the ability of this fluid to lubricate the serous membranes
prevent the heart from filling properly with blood
Hypercalcemia could cause ______. increased osteoclast activity prolonged T wave hypersecretion of parathyroid hormone All of the listed responses are correct.
prolonged T wave
The presence of an incompetent tricuspid valve would have the direct effect of causing ______. reduced efficiency in the delivery of blood to the lungs reduced efficiency in the delivery of blood to the myocardium reduced efficiency in the delivery of blood from the lungs to the heart reduced efficiency in the delivery of blood from the head to the heart
reduced efficiency in the delivery of blood to the lungs
The right tricuspid valve prevents backflow of blood from the right ventricle into the __________. pulmonary trunk right atrium left atrium left ventricle
right atrium
Which chamber receives blood from the superior and inferior vena cavae? left ventricle right atrium left atrium right ventricle
right atrium
What is the main function of heart valves? to separate the left and right atria to separate the atria and ventricles to pump blood through the heart to prevent backward flow of blood
to prevent backward flow of blood
The heart is actually (one, two, or three) pumps? three pumps one pump two pumps
two pumps
As part of a blood drive on campus for the American Red Cross, you and your friends have just donated 500 ml of blood. You are now relaxing at the student lounge, waiting for A&P lab to begin. Unfortunately, even though you are thirsty, you haven't bothered to buy yourself a drink. Other than a little soreness of the skin and tissue around your median cubital vein, you feel fine. How has your 500 ml decrease in blood volume most likely affected your cardiac output, heart rate, and stroke volume? decrease in cardiac output, decreased heart rate, decreased stroke volume no change in cardiac output, decreased heart rate, increased stroke volume increase in cardiac output, increased heart rate, increased stroke volume no change in cardiac output, increased heart rate, decreased stroke volume
no change in cardiac output, increased heart rate, decreased stroke volume
Trace the pathway of stimulation through the heart. Which of these pathways shows stimulation in the correct order? subendocardial conducting network, interventricular septum, AV bundle, AV node AV bundle, subendocardial conducting network, interventricular septum, SA node SA node, interventricular septum, AV node, papillary muscles AV node, AV bundle, interventricular septum, subendocardial conducting network
AV node, AV bundle, interventricular septum, subendocardial conducting network
Calculate the stroke volume if the end diastolic volume (EDV) is 135 mL/beat and the end systolic volume (ESV) is 60 mL/beat. 60 mL/beat 75 mL/beat 205 mL/beat 8100 mL/beat
75 mL/beat (The SV is calculated by subtracting the ESV from the EDV. You are comparing the volume of the ventricle at its fullest to its emptiest.)
Which of these structures conduct(s) action potentials the slowest? Purkinje fibers AV node AV bundle Bundle branches
AV node
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles? bundle branches AV node Purkinje fibers SA node AV bundle (bundle of His)
AV node
A person notices his or her heart beat because he or she senses blood being pumped by the heart. Excessive caffeine intake can lead to irregular heart rhythms (arrhythmias) that patients perceive as "skipped beats." Given that caffeine is a stimulant, which of the following mechanisms best explains the reason for the feeling that the heart skipped a beat? Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early. Action potentials are not delayed sufficiently at the AV node. Action potentials propagate into the ventricles before the contractile cells have repolarized from the previous heartbeat. Spontaneous action potentials in the SA node overlap such that the repolarizing phase of one action potential cancels out the depolarizing phase of the next.
Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early. (certain drugs, such as caffeine, nicotine, or cocaine, can stimulate other pacemaker cells to speed up and temporarily "escape" the SA node rhythm. If this ectopic focus consists of Purkinje fibers, then ventricular contraction will occur prematurely, prior to ventricular filling. Without proper filling, this abnormal contraction pumps little blood and is not sensed.)
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a heartbeat? AV bundle Internodal pathway AV node SA node
SA node
What heart problem would be experienced by an individual whose ECG is seen at C? The atria are not pumping blood. The heart is not pumping any blood at all. The ventricles are not reaching systole in every cardiac cycle. The heart would pump with too much pressure (hypertension).
The ventricles are not reaching systole in every cardiac cycle. (This condition is known as a second-degree heart block. Some signals from the AV node are not being conducted to the ventricles.)
What is happening during the "pause" phase when the heart is resting (relaxing)? Valves are closing. Ventricles are filling. Ventricles are contracting. Atria are contracting.
Ventricles are filling.
Suppose a patient develops a myocardial infarction that disables the sinoatrial node. Would the heart still pump blood to the aorta and the pulmonary trunk? No, because there will be no contraction of the atria. Yes, because the atrioventricular node will still stimulate ventricular systole. No, because there would be no more connection between the atrioventricular node and the bundle branches. Yes, because the ventricles will depolarize on their own without nodal stimulation at a rate of 50 times per minute.
Yes, because the atrioventricular node will still stimulate ventricular systole.
A patent ductus arteriosus permits ______. the deoxygenated blood pumped out by the left ventricle to quickly flow into the pulmonary trunk blood to flow from the aorta into the pulmonary trunk blood to enter the pulmonary trunk from the aorta because the higher blood pressure in the pulmonary trunk forces blood to flow into the pulmonary trunk All of the listed responses are correct.
blood to flow from the aorta into the pulmonary trunk
What causes the abnormal swishing or whooshing sound that is heard as blood regurgitates back into an atrium from its associated ventricle? semilunar valve closure blood turbulence pulmonary trunk expansion aortic recoil
blood turbulence
The beginning of the QRS complex of the electrocardiogram (ECG) immediately precedes which of the following events? blood ejection from the ventricles closing of the atrioventricular valves atrial contraction closing of the semilunar valves
closing of the atrioventricular valves ( As the ventricles contract, the increase in ventricular pressure closes the atrioventricular valves, beginning isovolumetric contraction.)
An increase in sympathetic stimulation of the heart would increase stroke volume by increasing __________. contractility end diastolic volume heart rate end systolic volume
contractility
In what direction does blood flow through the heart? View Available Hint(s) from a region of high pressure to a region of low pressure from a region of high oxygen content to a region of low oxygen content from a region of high volume to a region of low volume from ventricles to atria
from a region of high pressure to a region of low pressure (Blood moves through the heart from atria to ventricles and out large arteries, always from areas of high pressure to areas of lower pressure through one-way valves.)
What causes the aortic semilunar valve to close? equal ventricular and aortic pressures greater pressure in the aorta than in the left ventricle higher ventricular pressure than aortic pressure
greater pressure in the aorta than in the left ventricle ( backflow of blood in the aorta (towards the left ventricle) closes the aortic semilunar valve.)
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling. ventricular ejection, ventricular relaxation, isovolumetric contraction isovolumetric relaxation, ventricular ejection, isovolumetric contraction isovolumetric contraction, ventricular ejection, isovolumetric relaxation ventricular ejection, isovolumetric contraction, isovolumetric relaxation
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
Failure in a particular structure of the heart tends to cause a backup of blood in the lungs, known as pulmonary congestive heart failure. Failure of which structure of the heart would lead to such a backup? left ventricle pulmonary semilunar valve right ventricle right atrium
left ventricle
The greater the mass of tissue in an organ, the greater its need for an adequate blood supply. Which chamber of the heart has the highest probability of being the site of a myocardial infarction? right atrium left atrium left ventricle right ventricle
left ventricle
Which chamber of the heart sends oxygenated blood directly to the systemic circuit via the aorta? left atrium right atrium right ventricle left ventricle
left ventricle
A blockage in which of these vessels would most likely cause a myocardial infarction in the lateral right side of the heart? right marginal artery posterior interventricular artery anterior interventricular artery circumflex artery
right marginal artery
Specifically, what part of the intrinsic conduction system stimulates the atrioventricular (AV) node to conduct impulses to the atrioventricular bundle? bundle branches subendocardial conducting network (Purkinje fibers) sinoatrial (SA) node interventricular septum
sinoatrial (SA) node
The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important? because the Purkinje fibers conduct action potentials away from the heart apex because the AV bundle is the only electrical connection between the atria and the ventricles so blood is forced upward, toward the semilunar valves so the atria can finish contracting before the ventricles contract
so blood is forced upward, toward the semilunar valves (This makes ventricular ejection more efficient, much like squeezing a tube of toothpaste up from the bottom is more efficient at dispensing the toothpaste than is squeezing from the top.)
Consider the following characteristics of the cells found in muscle tissue. Which feature is shared by both cardiac muscle and skeletal muscle? intercalated discs branched cells striations triads
striations
When an ectopic pacemaker leads to an extrasystole, the ______. SA node has to increase its rate of activity in order to keep up with the ectopic pacemaker's activity SA node has to decrease its rate of activity in order to allow the ectopic pacemaker's activity to set the pace ventricles contract without any significant force ventricles contract before the atria contract
ventricles contract before the atria contract (The conduction system normally follows an ordered excitation route starting with SA node firing, which stimulates atrial contraction. As the Purkinje fibers depolarize and excite the ventricular myocardium, they contract.)
What does the QRS complex represent in the ECG wave tracing? ventricular depolarization ventricular repolarization atrial repolarization atrial depolarization
ventricular depolarization
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________. ventricular systole ventricular diastole
ventricular diastole (both occur during ventricular diastole when the ventricles are not actively contracting and ejecting blood.)
Most of the increase in left ventricular volume takes place during what phase of the cardiac cycle? atrial contraction ventricular filling isovolumetric relaxation ventricular ejection
ventricular filling
At what point in the cardiac cycle is pressure in the ventricles the highest (around 120 mm Hg in the left ventricle)? ventricular systole mid-to-late diastole (atrial contraction) early diastole (isovolumetric relaxation) ventricular filling
ventricular systole
Repolarization of an autorhythmic cell is due to the opening of which channels? Chemically gated potassium channels voltage-gated sodium channels chemically gated calcium channels voltage-gated potassium channels
voltage-gated potassium channels
At what point in the cardiac cycle does the semilunar valve close? when atrial pressure becomes greater than ventricular pressure when ventricular pressure becomes greater than aortic pressure when ventricular pressure becomes greater than atrial pressure when pressure in the ventricle becomes less than aortic pressure
when pressure in the ventricle becomes less than aortic pressure
At what point in the cardiac cycle does the semilunar valve open? when the AV valve closes when atrial pressure becomes greater than ventricular pressure when ventricular pressure becomes greater than aortic pressure when ventricular pressure becomes greater than atrial pressure
when ventricular pressure becomes greater than aortic pressure
At what point during the cardiac cycle does the AV valve close? when the semilunar valve opens when ventricular pressure becomes greater than atrial pressure when aortic pressure becomes greater than ventricular pressure when ventricular pressure becomes greater than aortic pressure
when ventricular pressure becomes greater than atrial pressure
