Unit6: Ch 25 (Porth's 5th Ed) - Structure and Function of the Cardiovascular System Flashcards
- As part of presurgical teaching for patients who are about to undergo a coronary artery
bypass graft, a nurse is performing an education session with a group of surgical
candidates. Which of the following teaching points best conveys an aspect of the human
circulatory system?
A) “The blood pressure varies widely between arteries and veins and between
pulmonary and systemic circulation.”
B) “Only around one quarter of your blood is in your heart at any given time.”
C) “Blood pressure and blood volume roughly mimic one another at any given
location in the circulatory system.”
D) “Left-sided and right-sided pumping action on each beat of the heart must equal
each other to ensure adequate blood distribution.”
Ans: A
Feedback:
There is a large variation between the higher pressure in the systemic circulatory system
and arteries and the lower pressure in the pulmonary system and veins. Approximately
8% of the blood supply is in the heart at any given time. Blood pressure and blood
volume are inversely proportionate. The body is able to accommodate short-term
differences in left-sided and right-sided output.
- In which of the following situations would blood most likely rapidly relocate from
central circulation to the lower extremities?
A) A client undergoes a stress test on a treadmill.
B) A client does isotonic exercises in a wheelchair
C) A client is helped out of bed and stands up.
D) A client reclines from a sitting to supine position.
Ans: C
Feedback:
During a change in body position, blood is rapidly relocated from the central circulation
(when the patient is recumbent) to the lower extremities (when the patient stands up).
This results in a temporary drop in blood pressure known as postural hypotension and
reflects the redistribution of blood in the body
- Which of the following statements 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 flow is primarily determined by blood viscosity and temperature.
C) Blood flows most quickly in the small diameter peripheral capillaries.
D) Smaller cross-sectional vessel area is associated with lower flow velocity.
Ans: A
Feedback:
Doubling the radius of a vessel is associated with a fourth-power increase in flow,
provided 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.
- 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 patient that she has aortic stenosis. After the cardiologist has left the room, the
patient asks, “What caused this [aortic stenosis] to happen now?” The clinic nurse
responds,
A) “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.”
B) “Aortic stenosis is commonly seen in elderly patients. Basically, there is a
blockage in the valve that is causing blood to pool, causing decreased velocity of
flow.”
C) “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.”
D) “Because of the high amount of energy it takes to push blood through the aortic
valve to the body, your valve is just had to work too hard and it is weakening.”
Ans: A
Feedback:
Heart murmur results from turbulent flow through a diseased heart valve that may be too
narrow, too stiff, or too floppy. This turbulent flow causes a vibration called a murmur
- A physician is teaching a group of medical students about the physiological basis for
damage to the circulatory and neurological systems that can accompany hypotension.
Which of the following responses by a student would warrant correction by the
physician?
A) “As vessel wall thickness increases, tension decreases.”
B) “Smaller blood vessels require more pressure to overcome wall tension.”
C) “The smaller the vessel radius, the greater the pressure needed to keep it open.”
D) “Tension and vessel thickness increase proportionately.”
Ans: D
Feedback:
Tension and vessel wall thickness are inversely proportionate, in that thinner blood
vessels have greater tension and vice versa. Answer choices A, B, and C all express the
correct inverse relationship between tension and wall thickness.
- During an automobile accident where the patient is bleeding heavily, which vascular
component is the most distensible and can store large quantities of blood that can be
returned to the circulation at this time of need?
A) Liver and pancreas
B) Kidneys
C) Veins
D) Aorta
Ans: C
Feedback:
Compliance refers to the total quantity of blood that can be stored in a given portion of
the circulation for each mm Hg rise in pressure. The most distensible of all vessels are
the veins, which can increase their volume with only slight changes in pressure. This
allows the veins to function as a reservoir for storing large quantities of blood that can
be returned to the circulation when it is needed. The liver, pancreas, and kidneys are not
vascular components.
- A client has suffered damage to his pericardium following a motor vehicle accident.
Which consequence could be a possible complication of damaged pericardium that his
care providers should assess for?
A) Impaired physical restraint of the left ventricle
B) Increased friction during the contraction/relaxation cycle
C) Reduced protection from infectious organisms
D) Impaired regulation of myocardial contraction
Ans: D
Feedback:
Regulation of myocardial contraction is not a role of the fibrous covering around the
heart. The pericardium does restrain the left ventricle, reduce friction by way of fluid in
the pericardial cavity, and provide a physical barrier to infection.
- A pathologist is examining histological (tissue) samples from a client with an
autoimmune disease. Which of the following characteristics of muscle samples would
signal the pathologist that the samples are cardiac rather than skeletal muscle?
A) The cell samples lack intercalated disks.
B) The muscle cells have small and a few mitochondria.
C) The cells have a poorly defined sarcoplasmic reticulum.
D) The muscles are striated and composed of sarcomeres.
Ans: C
Feedback:
Cardiac cells have a less clearly defined sarcoplasmic reticulum than do skeletal
muscles. They also have intercalated disks and large, numerous mitochondria. Both
types of muscles are striated and composed of sarcomeres
- An 81-year-old female client of a long-term care facility has a history of congestive
heart failure. The nurse practitioner caring for the client has positioned her sitting up at
an angle in bed and is observing her jugular venous distention. Why is jugular venous
distention a useful indicator for the assessment of the client’s condition?
A) Increased cardiac demand causes engorgement of systemic blood vessels, of
which the jugular vein is one of the largest.
B) Blood backs up into the jugular vein because there are no valves at the point of
entry into the heart.
C) Peripheral dilation is associated with decreased stroke volume and ejection
fraction.
D) Heart valves are not capable of preventing backflow in cases of atrial congestion.
Ans: B
Feedback:
Because there are no valves at the entry points to the atria, congestion can result in
engorgement of the jugular veins, which are proximal to the heart. Increased cardiac
demand is not associated with engorgement of vessels or peripheral dilation.
- 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 of the
following teaching points best captures a component of cardiac function?
A) “Efficient heart function requires that the ventricles do not retain any blood at the
end of the cardiac cycle.”
B) “Recall that the heart sounds that we listen to as part of our assessments are the
sounds of the myocardium contracting.”
C) “The diastolic phase is characterized by relaxation of ventricles and their filling
with blood.”
D) “Aortic pressure will exceed ventricular pressure during systole.”
Ans: C
Feedback:
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 patient is experiencing impaired circulation secondary to increased systemic arterial
pressure. Which of the following statements is the most relevant phenomenon?
A) Increased preload due to vascular resistance
B) High afterload because of backpressure against the left ventricle
C) Impaired contractility due to aortic resistance
D) Systolic impairment because of arterial stenosis
Ans: B
Feedback:
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
- In the ICU, the nurse hears an emergency cardiac monitor go off. The nurse looks at the
telemetry and notices the patient has gone into ventricular tachycardia. The nurse will
likely assess for signs/symptoms of
A) development of hypertension with BP 190/98.
B) oxygen deprivation with O2 saturation decreasing to approximately 90%.
C) decreasing cardiac output due to less ventricular filling time.
D) increasing cardiac index by correlating the volume of blood pumped by the heart
with an individual’s body surface area.
Ans: C
Feedback:
One of the dangers of ventricular tachycardia is a reduction in cardiac output because
the heart does not have time to fill adequately.
- A nurse is using a stethoscope and blood pressure cuff to manually measure a client’s
blood pressure. The nurse knows that which of the following facts related to blood flow
underlies the ability to hear blood pressure by auscultation (listening)?
A) The force of blood with each cardiac contraction produces friction on vessel walls
that can be heard and felt.
B) The movement of smooth muscle surrounding vessels produces noise that is
audible by a stethoscope.
C) Turbulent flow of blood during systole produces sound while laminar flow during
diastole is silent.
D) Pressure pulsation that exceeds the velocity of blood flow is audible and coincides
with systolic BP.
Ans: D
Feedback:
The pressure pulsations that accompany intermittent blood ejection from the ventricles
cause sounds that are audible when measuring blood pressure and palpable at pulse
sites. Friction, muscle movement, and turbulent blood flow do not account for the
pressure pulsations.
- Analysis has shown that a client’s right atrial pressure is 30 mm Hg. What is the most
likely conclusion that the client’s care team will draw from this piece of data?
A) The result is likely normal and gravity dependent given the lack of valves in
thoracic and central veins.
B) The pressure is insufficient to provide adequate stroke volume and cardiac output.
C) The pressure is excessive given that the right atrium should be at atmospheric
pressure.
D) Pressure pulsations are likely to be undetectable given the low atrial pressure
Ans: C
Feedback:
Normal right atrial pressure is around 0 mm Hg, or atmospheric pressure. Right atrial
pressure does not have a direct influence on stroke volume or pulse pressure.
- A patient arrived at the emergency department 2 days after the development of “chest
pressure” and “tightness” was treated with antacids thinking it was indigestion. His
enzymes show a massive myocardial infarction (MI). Following angioplasty, the patient
asks why so much muscle was damaged if only one vessel was blocked, the left
circumflex. The nurse responds,
A) “With any blockage in the heart, muscle damage always occurs.”
B) “If a major artery like the circumflex is occluded, the smaller vessels supplied by
that vessel cannot restore the blood flow.”
C) “Since the circumflex artery supplies oxygenated blood flow to the posterior
surface of the left ventricle, any amount of blockage will result in vital muscle
tissue being lost.”
D) “When it comes to arteries in the heart, all vessels are equal, and any blockage
causes a massive amount of damage that will not be restored.”
Ans: B
Feedback:
Hyperemia cannot occur when the arteries that supply the capillary beds are narrowed.
For example, if a major coronary artery becomes occluded, the opening of channels
supplied by that vessel cannot restore blood flow.
