Maintenance of the Body
four pressures that causes bulk ﬂow at capillaries (see Figure 19.17).
First you encounter Mrs. Taylor in the medical ward awaiting
a liver transplant. What is the connection between liver
failure and her edema? (Hint: ±ink about the liver’s role in
producing plasma proteins.)
Next you follow a resident to the obstetric ward, where Mrs.
So is experiencing premature labor. Which of the pressures
that drive bulk ﬂow might be altered here? (Hint: What
might the expanded uterus be pressing on?)
±en you are called to emergency, where Mr. Herrera is in
anaphylactic shock. In anaphylactic shock, the capillaries
become leaky, allowing plasma proteins that are normally
kept inside the blood vessels to escape into the interstitial
ﬂuid. Which of the pressures driving bulk ﬂow is altered in
this case and in what direction is the change?
Finally, you go to the oncology ward where Mrs. O’Leary is
recovering from surgery for advanced breast cancer that had
inﬁltrated her right breast and axillary lymph nodes. All of her
axillary lymph nodes were removed and unfortunately, this
severed most of the lymphatic vessels draining her right arm.
You notice that her right arm is quite edematous. Why? Mrs.
O’Leary is given a compression sleeve to wear on this arm to
help relieve the edema. Which of the pressures driving bulk
ﬂow at the capillaries will be altered by the compression sleeve?
the pressure on the brain stem and cranial nerves.” ±e surgeons
were able to “replace the aneurysm with a section of plastic tubing,”
so the patient recovered. Joanie asks you what all this means.
Explain. (Hint: Check this chapter’s Related Clinical Terms below.)
±e Agawam High School band is playing some lively marches
while the coaches are giving pep talks to their respective
football squads. Although it is September, it is unseasonably hot
(88°F/31°C) and the band uniforms are wool. Suddenly, Harry
the tuba player becomes light-headed and faints. Explain his
fainting in terms of vascular events.
When we are cold or the external temperature is low, most venous
blood returning from the distal part of the arm travels in the
deep veins where it picks up heat (by countercurrent exchange)
from the nearby brachial artery en route. However, when we are
hot, and especially during exercise, venous return from the distal
arm travels in the superﬁcial veins and those veins tend to bulge
superﬁcially in a person who is working out. Explain why venous
return takes a diﬀerent route in the second situation.
Edema (swelling due to an increase in interstitial ﬂuid) is a
common clinical problem. On one of your ﬁrst days of an
introductory clinical experience, you encounter four patients who
all have severe edema for diﬀerent reasons. Your challenge is to
explain the cause of the edema. In each case, try to explain the
edema in terms of either an increase or a decrease in one of the
Related Clinical Terms
a widening) A balloonlike
outpocketing of an artery wall that places the artery at risk for
rupture; most o²en reﬂects gradual weakening of the artery by
chronic hypertension or atherosclerosis. ±e most common sites
of aneurysms are the abdominal aorta and arteries feeding the
brain and kidneys.
Diagnostic technique involving the infusion of a radiopaque
substance into the circulation for X-ray examination of speciﬁc
blood vessels. ±e major technique for diagnosing coronary
artery occlusion and risk of a heart attack.
urinate) A chemical that promotes urine
formation, thus reducing blood volume. Diuretic drugs are
frequently prescribed to manage hypertension.
of a vein accompanied by painful throbbing and redness of the
skin over the inﬂamed vessel. It is most o²en caused by bacterial
infection or local physical trauma.
cut) A venous incision or
puncture made for the purpose of withdrawing blood or
Procedure for removing varicose or spider veins. Tiny
needles are used to inject hardening agents into the abnormal
vein. ±e vein scars, closes down, and is absorbed by the body.
Condition of undesirable intravascular clotting
initiated by a roughened venous lining; o²en follows severe
episodes of phlebitis. An ever-present danger is that the clot may
detach and form an embolus.
AT T H E C L I N I C
Mr. Hutchinson, another middle-aged
victim of the collision on Route 91, has
a tourniquet around his thigh when
admitted in an unconscious state to
Noble Hospital. The emergency technician who brings him in states
that his right lower limb was pinned beneath the bus for at least 30
minutes. He is immediately scheduled for surgery. Admission notes
include the following:
Multiple contusions of lower limbs
Compound fracture of the right tibia; bone ends covered with
Right leg blanched and cold, no pulse
Blood pressure 90/48; pulse 140/min and thready; patient
Relative to what you have learned about tissue requirements for
oxygen, what is the condition of the tissues in the right lower limb?
Will the fracture be attended to, or will Mr. Hutchinson’s other
homeostatic needs take precedence? Explain your answer
choice and predict his surgical treatment.
What do you conclude regarding Mr. Hutchinson’s cardiovascular
measurements (pulse and BP), and what measures do you expect
will be taken to remedy the situation before commencing surgery?
(Answers in Appendix H)
Cardiovascular System: Blood Vessels