Answers
1. 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 heartbeat must equal
each other to ensure adequate blood distribution.": A
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 ditterences
in left-sided and right-sided output.
2. 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 a 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.
,3. 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 expo-
nential 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.
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 patient that she has aortic stenosis. After the cardi-
ologist 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 isScausingTbloodOtoMpool, causing decreased flow
velocity."
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 stitt, or too floppy.
This turbulent flow causes a vibration called a murmur.
5. A physician is teaching a group of medical students about the physiolog-
ical 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.
6. 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.