The Medical College - Page 47
147.
Which of the graphs lead(s) you to believe
that
there is a breakdown in the normal
thyroid-pitu-
itary functional relationship?
A.
I and III
C.
II
B.
III
D.
II and III
148.
A lack of iodine in the diet usually is
associated
with which disorder?
A.
acromegaly
C.
rickets
B.
goiter
D.
skin rash
149.
Thyroid stimulating hormone (TSH) is
produced
by which of the following?
A.
acidophils (alpha cells)
B.
basophils (beta cells)
C.
delta cells
D.
chromophobes
150.
Which of the following statements
concerning
the thyroid are correct?
A.
The gland is derived from the
pharynx
(foramen cecum of the tongue).
B.
Colloid is located extracellularly.
C.
T3-triiodothyronine and T4
thyroxine are
the active principles.
D.
All of the above.
151.
Hypersecretion of which hormone will result
in
acromegaly (giantism)?
A.
TSH--thyroid stimulating hormone
B.
STH--somatotropin (growth hormone)
C.
ACTH--adrenocorticotrophic hormone
D.
thyroxin
Passage II (Questions 152–156)
·
·
·
·
Mean
Aor
tic
Pressure
Ventricular Volume
Active
Passive
A
C
D
B
As the left ventricle of the heart contracts,
it gener-
ates a pressure, which when more than that in
the aorta
causes the ejection of a volume of blood. The
action of
the ventricle can be represented as the
relationship
between the volume of blood in the ventricle
and the
intraventricular pressure. The relationship
between
ventricular pressure and volume is known as the
Frank-
Starling Law of the Heart and is shown at
left.
The lower curve represents the pressure volume
rela-
tionship when the heart is being passively
filled with
blood during diastole (i.e., at rest). The
upper curve
represents the pressure-volume relationship as
a result
of contraction (i.e., systole). The volume at
Point A is
known as the end diastolic volume, which is the
vol-
ume of blood in the ventricle immediately
preceding
contraction. During systole, the ventricle
contracts, but
no blood is ejected until the pressure in the
ventricle
exceeds the pressure in the aorta. This phase
of the car-
diac cycle is known as isovolumetric
contraction and is
represented by line segment AB. When the aortic
valve
opens (Point C), blood is ejected without
further
increase in the ventricular pressure (line
segment BC).
Therefore, this phase of contraction is
isotonic and
results in the ejection of a volume of blood
known as
the stroke volume.
When the pressure that the ventricle can
generate
exactly equals the aortic pressure, the
ejection of blood
ceases, and the ventricle undergoes
isovolumetric
relaxation as represented by the line segment
CD. The
blood from the atrium then fills the ventricle,
and the
pressure increase is the result of passive
resistance of
the ventricle (curve DA).
152.
Assuming a constant mean aortic
pressure,
patients with renal failure may have an
increased
blood volume which results in an increased
end
diastolic volume in the ventricle. What
effect
does this increase have on cardiac
function?
I.
ventricular work remains constant
II.
stroke volume increases
III.
end systolic volume increases
IV.
ventricular work increases
A.
I, II, and III only
C.
II and IV only
B.
I and III only
D.
IV only
153.
Patients with hypertension have a higher
mean
aortic pressure. If end diastolic volume
stays
contant:
I.
stroke volume increases.
II.
ventricular work increases.
III.
end systolic volume decreases.
IV.
ventricular work may or may not
increase.
A.
I, II, and III only
C.
II and IV only
B.
I and III only
D.
IV only
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