CHAPTER 9 • CARDIOVASCULAR INTEGRATION, ADAPTATION, AND PATHOPHYSIOLOGY
233
the mixed vasodilator decreases pre-
load as well as afterload. Choice “b” is
incorrect because afterload is decreased.
Choice “d” is incorrect because reducing
afterload leads to a decrease in end-sys-
tolic volume, which increases in stroke
volume.
12. The correct answer is “c” because ven-
tricular filling (preload) is increased
(choice “d” is therefore incorrect)
because blood flows from the aorta
back into the ventricle during diastole
in aortic regurgitation; this increases
the volume of blood ejected into the
aorta, which increases aortic systolic
pressure (choice “b” is therefore incor-
rect). Choice “a” is incorrect because
the retrograde flow causes aortic
pressure to fall more rapidly during
diastole, which decreases the diastolic
pressure.
13. The correct answer is “b” because with
mitral stenosis, blood has difficulty
flowing from the left atrium into the
left ventricle. This leads to blood back-
ing up into the left atrium and increas-
ing its pressure. Choice “a” is incorrect
because turbulence occurs as blood
flows across the narrowed valve during
diastole, thereby producing a diastolic
murmur. Choice “c” is incorrect because
left ventricular filling can be impaired,
which decreases its end-diastolic volume
and pressure. Choice “d” is incorrect
because reduced ventricular filling is
accompanied by a reduced stroke vol-
ume; therefore, ejection fraction does
not change much.
ANSWERS TO CASES
CASE 9-1
Autonomic neuropathy affects the function
of most organ systems of the body because
autonomic nerves play a vital role in regu-
lating normal function. In the cardiovascu-
lar system, autonomic nerves, particularly
sympathetic adrenergic nerves, regulate
arterial pressure through their actions on
the heart and vasculature. Patients with type
2 diabetes who have impaired autonomic
control of the cardiovascular system may
have abnormal responses to exercise because
heart rate and inotropy may not increase
normally, and sympathetic stimulation
of the arterial and venous system may be
impaired. This loss of sympathetic control
may result in a fall in arterial pressure dur-
ing exercise owing to a greater-than-normal
reduction in systemic vascular resistance, a
decrease in central venous pressure owing to
loss of venous tone, and a reduction in car-
diac output caused by smaller-than-normal
increases in heart rate and stroke volume.
Hypotension during exercise impairs muscle
perfusion, causing fatigue. Decreased cere-
bral perfusion caused by hypotension can
lead to dizziness, visual disturbances, and
syncope.
CASE 9-2
Recovery from hemorrhage pardy involves
arterial and venous constriction, cardiac
stimulation, and renal retention of sodium
and water. The diuretic would counter the
normal renal compensatory mechanisms of
sodium and water retention. The ACE inhibi-
tor would reduce the formation of circulating
angiotensin II that normally plays an impor-
tant compensatory role through constricting
blood vessels and increasing blood volume by
enhancing renal reabsorption of sodium and
water. The calcium channel blocker, depend-
ing upon its class, would depress cardiac
function and cause systemic vasodilation,
both of which would counteract normal com-
pensatory responses to hemorrhage. These
drugs, therefore, would impair and prolong
the recovery process following hemorrhage.
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