SHORT ANSWER. Write the word or phrase that best completes each
statement or answers the question.
Figure 18.1 Using Figure 18.1, match the following: 1) Purkinje
fibers.
1)
Answer: EDiff: 1
Page Ref: 677; Fig. 18.14
2) SA node. Answer: ADiff: 1 Page Ref: 677; Fig. 18.14
2)
3) AV bundle. Answer: CDiff: 1 Page Ref: 677; Fig. 18.14
3)
4) AV node. Answer: BDiff: 1 Page Ref: 677; Fig. 18.14
4)
5) Bundle branches. Answer: DDiff: 1 Page Ref: 677; Fig.
18.14
5)
1
Figure 18.2 Using Figure 18.2, match the following: 6) Atrial
depolarization.
6)
Answer: ADiff: 1
Page Ref: 679; Fig. 18.16
7) Point after which pressure begins to rise in the aorta.
Answer: DDiff: 2 Page Ref: 679; Fig. 18.16
7)
8) Ventricular repolarization. Answer: EDiff: 2 Page Ref: 679;
Fig. 18.16
8)
9) Point that represents the "dup" sound made by the heart.
Answer: EDiff: 3 Page Ref: 679; Fig. 18.16
9)
2
Figure 18.3 Using Figure 18.3, match the following: 10)
Ventricular fibrillation.
10)
Answer: DDiff: 2
Page Ref: 681; Fig. 18.18
11) Second-degree heart block. Answer: CDiff: 3 Page Ref: 681;
Fig. 18.18
11)
12) Junctional rhythm. Answer: BDiff: 3 Page Ref: 681; Fig.
18.18
12)
3
13) Normal sinus rhythm. Answer: ADiff: 3 Page Ref: 681; Fig.
18.18
13)
MATCHING. Choose the item in column 2 that best matches each
item in column 1. Match the following: 14) The inner lining of the
heart. Answer: CDiff: 1 Page Ref: 664
A) Epicardium B) Myocardium C) Endocardium D) Parietal layer
14)
15) Heart muscle. Answer: BDiff: 1 Page Ref: 663
15)
16) Serous layer covering the heart muscle. Answer: ADiff: 1
Page Ref: 663
16)
17) The outermost layer of the serous pericardium. Answer:
DDiff: 2 Page Ref: 663
17)
Match the following: 18) The pacemaker of the heart. Answer:
ADiff: 1 Page Ref: 677; Fig. 18.14
A) SA node B) AV node C) AV bundle D) Purkinje fibers
18)
19) Found in the interventricular septum. Answer: CDiff: 1 Page
Ref: 677
19)
20) Network found in the ventricular myocardium. Answer: DDiff:
2 Page Ref: 677
20)
21) The point in the conduction system of the heart where the
impulse is temporarily delayed. Answer: BDiff: 2 Page Ref: 677
21)
4
Match the following: 22) Prevents backflow into the left
ventricle. Answer: DDiff: 1 Page Ref: 670
A) Tricuspid valve B) Mitral valve C) Pulmonary valves D) Aortic
valve
22)
23) Prevents backflow into the right atrium. Answer: ADiff: 1
Page Ref: 670
23)
24) Prevents backflow into the left atrium. Answer: BDiff: 1
Page Ref: 670
24)
25) Prevents backflow into the right ventricle. Answer: CDiff: 1
Page Ref: 670
25)
26) AV valve with two flaps. Answer: BDiff: 1 Page Ref: 670
26)
27) AV valve with three flaps. Answer: ADiff: 1 Page Ref:
670
27)
5
SHORT ANSWER. Write the word or phrase that best completes each
statement or answers the question.
Figure 18.4 Using Figure 18.4, match the following: 28)
Tricuspid valve.
28)
Answer: BDiff: 1
Page Ref: 667; Fig. 18.4e
29) Mitral valve. Answer: DDiff: 1 Page Ref: 667; Fig. 18.4e
29)
30) Right atrium. Answer: ADiff: 1 Page Ref: 667; Fig. 18.4e
30)
31) Left ventricle. Answer: EDiff: 1 Page Ref: 667; Fig.
18.4e
31)
32) Pulmonary veins. Answer: CDiff: 1 Page Ref: 667; Fig.
18.4e
32)
6
MATCHING. Choose the item in column 2 that best matches each
item in column 1. Match the following: 33) Heart muscle is deprived
of oxygen. Answer: ADiff: 1 Page Ref: 675
A) Ischemia B) Fibrillation C) Infarction D) Ectopic focus E)
Quiescent period
33)
34) Death of heart muscle cells. Answer: CDiff: 1 Page Ref:
670
34)
35) A condition of rapid and irregular or out-of-phase
contraction of heart muscle cells. Answer: BDiff: 1 Page Ref:
678
35)
36) An abnormal pacemaker. Answer: DDiff: 1 Page Ref: 679
36)
37) Total heart relaxation. Answer: EDiff: 1 Page Ref: 682
37)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the
statement is false. 38) The myocardium receives its blood supply
from the coronary arteries. Answer:Diff: 1 Page Ref: 670
38)
True
False
39) Cardiac muscle has more mitochondria and depends less on a
continual supply of oxygen than does skeletal muscle. Answer:Diff:
1 Page Ref: 673
39)
True
False
40) Anastomoses among coronary arterial branches provide
collateral routes for blood delivery to the heart muscle.
Answer:Diff: 2 Page Ref: 669
40)
True
False
41) Congestive heart failure means that the pumping efficiency
of the heart is depressed so that there is inadequate delivery of
blood to body tissues. Answer:Diff: 1 Page Ref: 687
41)
True
False
42) Tissues damaged by myocardial infarction are replaced by
connective tissue. Answer:Diff: 1 Page Ref: 670, 687
42)
True
False
7
43) The left side of the heart pumps the same volume of blood as
the right. Answer:Diff: 1 Page Ref: 668
43)
True
False
44) Chronic release of excess thyroxine can cause a sustained
increase in heart rate and a weakened heart. Answer:Diff: 1 Page
Ref: 686
44)
True
False
45) Arterial blood supply to heart muscle is continuous whether
the heart is in systole or diastole. Answer:Diff: 2 Page Ref:
669-670
45)
True
False
46) Trabeculae carneae are found in the ventricles and never the
atria. Answer:Diff: 1 Page Ref: 668
46)
True
False
47) The "lub" sounds of the heart are valuable in diagnosis
because they provide information about the function of the heart's
pulmonary and aortic valves. Answer:Diff: 2 Page Ref: 681
47)
True
False
48) Autonomic regulation of heart rate is via two reflex centers
found in the pons. Answer:Diff: 2 Page Ref: 685
48)
True
False
49) The papillary muscles contract after the other ventricular
muscles so that they can take up the slack on the chordae tendineae
before the full force of ventricular contractions sends blood
against the AV valve flaps. Answer:Diff: 2 Page Ref: 670
49)
True
False
50) An ECG provides direct information about valve function.
Answer:Diff: 3 Page Ref: 679
50)
True
False
51) As pressure in the aorta rises due to atherosclerosis, more
ventricular pressure is required to open the aortic valve.
Answer:Diff: 3 Page Ref: 687
51)
True
False
52) Proxysmal atrial tachycardia is characterized by bursts of
atrial contractions with little pause between them. Answer:Diff: 2
Page Ref: 690
52)
True
False
8
MULTIPLE CHOICE. Choose the one alternative that best completes
the statement or answers the question. 53) Normal heart sounds are
caused by which of the following events? A) excitation of the SA
node B) opening and closing of the heart valves C) closure of the
heart valves D) friction of blood against the chamber walls Answer:
CDiff: 1 Page Ref: 681
53)
54) Which of the events below does not occur when the semilunar
valves are open? A) AV valves are closed. B) Blood enters pulmonary
arteries and the aorta. C) Ventricles are in diastole. D)
Ventricles are in systole. Answer: CDiff: 2 Page Ref: 670
54)
55) Hemorrhage with a large loss of blood causes ________. A) no
change in blood pressure but a slower heart rate B) a lowering of
blood pressure due to change in cardiac output C) no change in
blood pressure but a change in respiration D) a rise in blood
pressure due to change in cardiac output Answer: BDiff: 1 Page Ref:
682-684
55)
56) The left ventricular wall of the heart is thicker than the
right wall in order to ________. A) pump blood through a smaller
valve B) pump blood with greater pressure C) expand the thoracic
cage during diastole D) accommodate a greater volume of blood
Answer: BDiff: 2 Page Ref: 668
56)
57) Damage to the ________ is referred to as heart block. A) AV
node B) SA node C) AV bundle Answer: ADiff: 1 Page Ref: 679
D) AV valves
57)
58) The P wave of a normal electrocardiogram indicates ________.
A) atrial repolarization B) ventricular repolarization C)
ventricular depolarization D) atrial depolarization Answer: DDiff:
1 Page Ref: 679
58)
59) Blood within the pulmonary veins returns to the ________. A)
right ventricle B) left ventricle C) right atrium Answer: DDiff: 1
Page Ref: 668
D) left atrium
59)
9
60) Small muscle masses attached to the chordae tendineae are
the ________. A) trabeculae carneae B) papillary muscles C) venae
cavae D) pectinate muscles Answer: BDiff: 1 Page Ref: 670
60)
61) The term for pain associated with deficient blood delivery
to the heart that may be caused by the transient spasm of coronary
arteries is ________. A) angina pectoris B) myocardial infarct C)
pericarditis D) ischemia Answer: ADiff: 1 Page Ref: 670
61)
62) To auscultate the aortic semilunar valve, you would place
your stethoscope in the ________. A) second intercostal space to
the left of the sternum B) fifth intercostal space inferior to the
left nipple C) second intercostal space to the right of the sternum
D) fifth right intercostal space Answer: CDiff: 1 Page Ref: 681;
Fig. 18.19
62)
63) The source of blood carried to capillaries in the myocardium
would be the ________. A) fossa ovalis B) coronary veins C)
coronary arteries D) coronary sinus Answer: CDiff: 1 Page Ref:
669
63)
64) The fact that the left ventricle of the heart is thicker
than the right ventricle reveals that it ________. A) expands the
thoracic cage B) pumps a greater volume of blood C) sends blood
through a smaller valve D) pumps blood against a greater resistance
Answer: DDiff: 1 Page Ref: 668
64)
65) Which of the following factors does not influence heart
rate? A) skin color B) body temperature C) gender D) age Answer:
ADiff: 1 Page Ref: 685-687
65)
66) Which of the following is not an age-related change
affecting the heart? A) fibrosis of cardiac muscle B) decline in
cardiac reserve C) thinning of the valve flaps D) atherosclerosis
Answer: CDiff: 2 Page Ref: 686-687
66)
10
67) If cardiac muscle is deprived of its normal blood supply,
damage would primarily result from ________. A) an inadequate
supply of lactic acid B) a decrease in the number of available
mitochondria for energy production C) decreased delivery of oxygen
D) a lack of nutrients to feed into metabolic pathways Answer:
CDiff: 1 Page Ref: 675
67)
68) If the length of the absolute refractory period in cardiac
muscle cells was the same as it is for skeletal muscle cells
________. A) tetanic contractions might occur, which would stop the
heart's pumping action B) contractions would last as long as the
refractory period C) it would be much longer before cardiac cells
could respond to a second stimulation D) it would be less than 1 2
ms Answer: ADiff: 2 Page Ref: 673
68)
69) Norepinephrine acts on the heart by ________. A) decreasing
heart contractility B) causing a decrease in stroke volume C)
causing threshold to be reached more quickly D) blocking the action
of calcium Answer: CDiff: 2 Page Ref: 685-686
69)
70) If the vagal nerves to the heart were cut, the result would
be that ________. A) the AV node would become the pacemaker of the
heart B) the heart rate would increase by about 25 beats per minute
C) the heart would stop, since the vagal nerves trigger the heart
to contract D) parasympathetic stimulation would increase, causing
a decrease in heart rate Answer: BDiff: 2 Page Ref: 686
70)
71) Foramen ovale ________. A) is a connection between the
pulmonary trunk and the aorta in the fetus B) is a shallow
depression in the interventricular septum C) connects the two atria
in the fetal heart D) is a condition in which the heart valves do
not completely close Answer: CDiff: 1 Page Ref: 688
71)
72) Which vessel of the heart receives blood during right
ventricular systole? A) aorta B) pulmonary veins C) pulmonary trunk
D) venae cavae Answer: CDiff: 1 Page Ref: 668, 682
72)
11
73) Which of these vessels receives blood during ventricular
systole? A) aorta only B) both the aorta and pulmonary trunk C)
pulmonary veins only D) pulmonary arteries only Answer: BDiff: 1
Page Ref: 682
73)
74) Which of the following is not part of the conduction system
of the heart? A) bundle of His B) AV node C) AV valve Answer:
CDiff: 1 Page Ref: 677; Fig. 18.14
D) SA node
74)
75) The tricuspid valve is closed ________. A) while the atrium
is contracting B) by the movement of blood from atrium to ventricle
C) when the ventricle is in systole D) while the ventricle is in
diastole Answer: CDiff: 2 Page Ref: 682; Fig. 18.20
75)
76) When viewing a dissected heart, it is easy to visually
discern the right and left ventricles by ________. A) noticing the
thickness of the ventricle walls B) tracing out where the auricles
connect C) finding the papillary muscles D) locating the apex
Answer: ADiff: 1 Page Ref: 668
76)
77) Select the correct statement about the heart valves. A) The
AV valves are supported by chordae tendineae so that regurgitation
of blood into the atria during ventricular contraction does not
occur. B) The tricuspid valve divides the left atrium from the left
ventricle. C) The mitral valve separates the right atrium from the
right ventricle. D) Aortic and pulmonary valves control the flow of
blood into the heart. Answer: ADiff: 2 Page Ref: 670
77)
78) Select the correct statement about the function of
myocardial cells. A) The refractory period in skeletal muscle is
much longer than that in cardiac muscle. B) Each cardiac muscle
cell is innervated by a sympathetic nerve ending so that the
nervous system can increase heart rate. C) The influx of potassium
ions from extracellular sources is the initiating event in cardiac
muscle contraction. D) The entire heart contracts as a unit or it
does not contract at all. Answer: DDiff: 3 Page Ref: 673-675
78)
12
79) Select the correct statement about the structure of the
heart wall. A) The fibrous skeleton forms the bulk of the heart. B)
The myocardium is the layer of the heart that actually contracts.
C) The heart chambers are lined by the endomysium. D) Connective
tissue in the heart wall aids in the conduction of the action
potential. Answer: BDiff: 2 Page Ref: 663-664
79)
80) Compared to skeletal muscle, cardiac muscle ________. A) has
gap junctions that allow it to act as a functional syncytium B)
lacks striations C) cells are larger than skeletal muscle cells D)
has more nuclei per cell Answer: ADiff: 2 Page Ref: 672-673
80)
81) During the period of ventricular filling ________. A) it is
represented by the P wave on the ECG B) pressure in the heart is at
its peak C) the atria remain in diastole D) blood flows passively
through the atria and the open AV valves into the ventricles
Answer: DDiff: 2 Page Ref: 682
81)
82) The second heart sound is heard during which phase of the
cardiac cycle? A) isovolumetric relaxation B) isovolumetric
contraction C) ventricular filling D) ventricular ejection Answer:
ADiff: 3 Page Ref: 682; Fig. 18.20
82)
83) The time of day most hazardous for heart attacks is
________. A) morning B) noontime C) evening Answer: ADiff: 3 Page
Ref: 685-686
D) during sleep
83)
84) If we were able to artificially alter the membrane
permeability of pacemaker cells so that sodium influx is more
rapid, ________. A) heart rate would decrease, but blood pressure
would rise due to the excess sodium present B) threshold is reached
more quickly and heart rate would increase C) potassium channels
compensate and no change in heart rate would occur D) tetanic
contraction would occur due to the short absolute refractory period
of cardiac muscle Answer: BDiff: 3 Page Ref: 676-677
84)
13
85) Select the correct statement about cardiac output. A) A slow
heart rate increases end diastolic volume, stroke volume, and force
of contraction. B) If a semilunar valve were partially obstructed,
the end systolic volume in the affected ventricle would be
decreased. C) Decreased venous return will result in increased end
diastolic volume. D) Stroke volume increases if end diastolic
volume decreases. Answer: ADiff: 3 Page Ref: 682-684
85)
86) During contraction of heart muscle cells ________. A) the
action potential is prevented from spreading from cell to cell by
gap junctions B) the action potential is initiated by voltage-gated
slow calcium channels C) calcium is prevented from entering cardiac
fibers that have been stimulated D) some calcium enters the cell
from the extracellular space and triggers the release of larger
amounts of calcium from intracellular stores Answer: DDiff: 2 Page
Ref: 673-675
86)
87) Isovolumetric contraction ________. A) occurs only in people
with heart valve defects B) occurs immediately after the aortic and
pulmonary valves close C) refers to the short period during
ventricular systole when the ventricles are completely closed
chambers D) occurs while the AV valves are open Answer: CDiff: 3
Page Ref: 682; Fig. 18.20
87)
88) Commotio cordis is heart failure due to a ________. A)
severe electrical shock to the body B) loss of blood from an artery
C) relatively mild blow to the chest that occurs during a
vulnerable interval (2 ms) when the heart is repolarizing D) mild
electrical shock to the heart itself Answer: CDiff: 3 Page Ref:
690
88)
SHORT ANSWER. Write the word or phrase that best completes each
statement or answers the question. 89) The enlarged coronary vessel
outside the heart that empties blood into the right atrium is the
________. Answer: coronary sinusDiff: 1 Page Ref: 669
89)
90) What structure in the fetal heart allows blood to flow from
the right atrium directly to the left atrium? Answer: foramen
ovaleDiff: 1 Page Ref: 688
90)
14
91) The ECG T wave interval represents ________. Answer:
ventricular repolarizationDiff: 1 Page Ref: 679; Fig. 18.16
91)
92) CO = ________ SV. Answer: HR or heart rateDiff: 1 Page Ref:
683
92)
93) The ________ membrane covers the heart. Answer: visceral
layer of the serous pericardiumDiff: 1 Page Ref: 663
93)
94) The ________ valve of the heart has three valves with
chordae tendineae. Answer: tricuspidDiff: 1 Page Ref: 670
94)
95) The ________ and ________ valves of the heart have no
chordae tendineae attached. Answer: aortic; pulmonaryDiff: 1 Page
Ref: 670; Fig. 18.9
95)
96) Define systole and diastole. Which heart chambers are
usually referenced when these terms are used? Answer: Systole is
contraction of the muscle. Diastole is relaxation of the muscle.
The contraction and relaxation of the ventricles are normally
described with the terms systole and diastole.Diff: 1 Page Ref:
682
96)
97) Define the terms end diastolic volume (EDV) and end systolic
volume (ESV) and relate them to the calculation of stroke volume.
Answer: EDV is the amount of blood that collects in a ventricle
during diastole. ESV is the volume of blood remaining in a
ventricle after it has contracted. Stroke volume (ml/beat) equals
EDV - ESV.Diff: 1 Page Ref: 684
97)
98) What is the difference between the auricles and the atria?
Answer: Auricles are the flaplike appendages attached to the atria
that increase the atrial volume. The atria are receiving chambers
for blood returning to the heart from the pulmonary and systemic
circulation.Diff: 1 Page Ref: 664
98)
99) The heart is called a "double pump" because there are two
functionally separate circulations. Trace the pathway of each of
these circulations and include the following information: heart
chambers involved, major blood vessels involved, and general areas
through which the blood flows. Begin with the right atrium. Answer:
Right atrium to right ventricle to pulmonary arteries to lungs
(pulmonary circuit pump); pulmonary veins to left atrium to left
ventricle to aorta to body tissues to venae cavae (systemic circuit
pump).Diff: 2 Page Ref: 668-670
99)
15
100) What two important functions does the cardiac conduction
system perform? Answer: The important functions of the cardiac
conduction system are to initiate impulses (pacemaker) and to
distribute impulses throughout the heart so that it depolarizes and
contracts in an orderly, sequential manner.Diff: 2 Page Ref:
676
100)
101) Explain autorhythmicity in cardiac muscle cells. Answer:
Autorhythmic cells do not maintain a stable resting membrane
potential. Instead, they have an unstable resting potential that
continuously depolarizes, drifting toward threshold for firing.
These spontaneously changing membrane potentials, called pacemaker
potentials, initiate the action potentials that trigger the hearts
rhythmic contractions.Diff: 3 Page Ref: 676
101)
102) Why is oxygen so much more critical to the heart muscle
than to skeletal muscles? Answer: Cardiac muscle cells are highly
dependent on oxygen and rely almost exclusively on aerobic
respiration. Thus, they cannot incur much oxygen debt. When there
is a forced switch to anaerobic respiration, lactic acid and rising
H + levels impair heartDiff: 3
102)
function.
Page Ref: 675
103) What is the functional importance of the intercalated discs
of cardiac muscle? What is the functional importance of the fibrous
skeleton of the heart? Answer: Intercalated discs contain anchoring
desmosomes that prevent cell separation, and gap junctions that
allow ions to travel from cell to cell, transmitting current across
the entire heart. The fibrous skeleton acts both as a tendon and an
insertion, giving the cardiac cells something to pull or exert
their force on.Diff: 2 Page Ref: 673
103)
104) What is bradycardia? Answer: Bradycardia is a heart rate
slower than 60 beats per minute.Diff: 1 Page Ref: 687
104)
105) Why is fibrosis of the cardiac muscle serious? Answer: With
fibrosis the heart muscle stiffens and is unable to fill the atria
as it once did; therefore, less blood is pumped. Further, as the
muscle stiffens it takes more energy to expel the bolus of blood
from the heart, which will eventually weaken the heart.Diff: 2 Page
Ref: 689
105)
ESSAY. Write your answer in the space provided or on a separate
sheet of paper. 106) A 14-year-old girl undergoing a physical
examination prior to being admitted to summer camp was found to
have a loud heart diastolic murmur at the second intercostal space
to the left side of the sternum. Explain the reason for the loud
heart murmur associated with this girl's condition. Answer: The
heart murmur is due to incomplete closing of the pulmonary
valve.Diff: 2 Page Ref: 681
16
107) A man enters the hospital complaining of chest pain. His
history includes smoking, a stressful job, a diet heavy in
saturated fats, lack of exercise, and high blood pressure. Although
he is not suffering from a heart attack, his doctor explains to him
that a heart attack is quite possible. What did the chest pain
indicate? Why is this man a prime candidate for a heart attack?
Answer: His symptoms indicate angina pectoris, possibly due to
either atherosclerosis or stress-induced spasms of the coronary
arteries. If the arteries are occluded (atherosclerosis), the heart
muscle could be deprived of blood, and therefore oxygen. A heart
attack could occur if the coronary vessels experience further (or
progressive) occlusion.Diff: 3 Page Ref: 670
108) An older woman complains of shortness of breath and
intermittent fainting spells. Her doctor runs various tests and
finds that the AV node is not functioning properly. What is the
suggested treatment? Answer: The suggested treatment is surgery to
implant an artificial pacemaker.Diff: 2 Page Ref: 678-679
109) An angiocardiogram was performed on an infant who had
symptoms of breathlessness and it was found that he had a patent
ductus arteriosus. Discuss the location and function of the ductus
arteriosus in the fetus and relate it to the reason for the
infant's breathlessness. Answer: The ductus arteriosus is a shunt
between the pulmonary trunk and the aorta in the fetus, which
normally closes at birth. Breathlessness is due to the mixing of
oxygenated and deoxygenated blood because the connection between
the aorta and the pulmonary trunk remains slightly open.Diff: 2
Page Ref: 689
110) A patient takes a nitroglycerin tablet sublingually for
chest pain. Nitroglycerin acts directly on smooth muscle, producing
relaxation and vessel dilation. How would this relieve chest pain?
Answer: Angina pectoris is thoracic pain caused by a fleeting
deficiency in blood delivery to the myocardium, with resulting
decreased oxygen being delivered to the cells. Because
nitroglycerin acts as a vasodilator, blood flow is increased,
promoting the delivery of oxygen to the cells.Diff: 3 Page Ref:
670
111) A patient was admitted to the hospital with chest pains. On
admission, his pulse was 110 and blood pressure was 96/64.
According to his history, his normal pulse rate is usually between
80 and 88 and his blood pressure runs from 120/70 to 130/80.
Explain why these changes in BP and HR occur. Answer: Increased
heart rate (measured by taking his pulse) without maintaining his
normal blood pressure is suggestive of reduced stroke volume. Both
a drop in blood volume and a weakened heart could cause this, but
the chest pains suggest heart damage. Failure of compensating
mechanisms to maintain blood pressure suggest a serious decline in
cardiac output.Diff: 3 Page Ref: 682, 684
17
112) A 55-year-old male was admitted to the hospital with heart
failure. He complains of increasing shortness of breath on exertion
and needing to sleep on three pillows at night. On physical
assessment, the nurse determines that his ankles and feet are very
swollen. Which of these symptoms reflect left-sided heart failure
and which reflect right-sided heart failure? Answer: Because the
heart is a double pump, each side can initially fail independently
of the other. If the left side fails, pulmonary congestion occurs.
The right side of the heart continues to propel blood to the lungs,
but the left side does not adequately eject the returning blood
into the systemic circulation. Thus, blood vessels in the lungs
become engorged with blood, pressure within them increases, and
fluid leaks from the circulation into the lung tissue, causing
pulmonary edema. Shortness of breath and difficulty breathing in a
prone position may occur.If the right side of the heart fails,
peripheral congestion occurs. Blood stagnates within body organs,
and pooled fluids in the tissue spaces impair the ability of body
cells to obtain adequate nutrients and oxygen and to rid themselves
of wastes. Edema is most noticeable in the extremities (feet,
ankles, and fingers).Page Ref: 687
Diff: 3
113) Asystole is the total absence of ventricular electrical
activity. Explain why defibrillation would not be effective in this
situation. Answer: Defibrillation is accomplished by electrically
shocking the heart, which interrupts its chaotic twitching by
depolarizing the entire myocardium. In this case, the ventricles
are at a total standstill and defibrillation would not be
effective.Diff: 3 Page Ref: 678-679
114) A patient is prescribed a calcium channel blocker to
prevent angina (chest pain), by decreasing the demand for oxygen.
Explain why. Answer: By preventing the influx of calcium ions into
myocardial and vascular smooth muscle cells, calcium channel
blockers inhibit the intracellular release of additional stores of
calcium ions. A drug that inhibits the release of intracellular
calcium ions decreases the force of myocardial contractility,
thereby decreasing the oxygen demand.Diff: 3 Page Ref: 676, 687
18