The Medical College - Page 69
The writing in this paper is clear and well
controlled.
Each of the paragraphs is organized around a
topic that
gives unity to the paper. Its sentences are
varied and flow
nicely from one to the next. The weakest aspect
of the
paper is that it lacks concrete details to
illustrate its
points from the beginning of paragraph two to
the end.
With the addition of such details and with a
direct con-
frontation of the task in paragraph two, its
rating would
move to 5 or 6.
BIOLOGICAL SCIENCES
143.
C.
Thyroid stimulating hormone (TSH)
pro-
duced by the pituitary gland stimulates the
thy-
roid gland to produce its hormones
T3
(triiodothyronine) and T4 (tetraiodothyronine
or
thyroxine). TSH modulates the iodide
trapping
mechanisms; hypersecretion results in goiter
and
exophthalmos, whereas hyposecretion leads
to
diminished thyroid function and
lethargy.
144.
B.
See explanation for question 143.
145.
C.
When thyroxin is administered, one
would
expect that the iodide uptake would decrease;
in
graph I it stayed level, whereas in graph III
an
increase of uptake is exhibited. Both
experimen-
tal conditions indicate some evidence of
thyroid
malfunction.
146.
B.
A hyperthyroid individual would not
be
expected to show additional uptake because
the
gland already is working at an elevated
level.
When thyroid hormone was administered as
in
our experiments, normally the uptake
should
have decreased; it stayed the same
however.
147.
A.
When thyroxin is administered, TSH
pro-
duction diminishes and RAI uptake should
drop.
This did not occur in graph I while graph
II
demonstrates the expected normal. Graph
III
shows an increase in uptake indicating that
the
pituitary is not responding to the
negative
inhibitory feedback that thyroxin elicits;
TSH
production should decrease at the time of
thyrox-
ine administration.
148.
B.
Acromegaly is a result of pituitary
over-
secretion of growth hormone. Lack of iodine
will
result in goiter development of the thyroid
gland.
Rickets is due to vitamin D deficiency. A
skin
rash is not a specific lesion that can be
associated
with only one specific cause as the others
listed.
149.
B.
Acidophils produce somatotropic
hormone
(STH) and luteotropic hormone (LTH) or
prolactin.
Beta cells produce thyroid stimulating
hormone
(TSH), adrenocorticotropic hormone (ACTH),
and
melanocyte stimulating hormone (MSH).
Delta
cells produce luteinizing hormone (LH)
(called
interstitial cell stimulating hormone in
the
male), and follicle stimulating hormone
(FSH).
Chromophobes are considered resting
cells.
150.
D.
All statements are correct. The thyroid
origi-
nates from the foramen cecum region of
the
tongue. Its structural unit is the follicle, a
unit of
epithelial cells that surround a colloid space.
Col-
loid is located extracellularly and contains
thy-
roglobulin. T3
and T4
are the active thyroid
principles and are released into the
bloodstream
and carried on proteins to the
tissues.
151.
B.
Acromegaly and (or) giantism is due to
over-
activity of the alpha cells of the pituitary,
which
secrete growth hormone. If a person is
affected
before puberty, he or she will develop into a
fairly
well-proportioned giant. After maturity, an
increase
in the size of the hands and feet and massive
devel-
opment of the bones comprising the face are
conse-
quences. In the adult, strictly speaking, the
term
acromegaly must be applied to this
condition.
152.
C.
If aortic pressure is unchanged and end
diastolic
volume increases, the stroke volume or the
differ-
ence between end diastolic volume and end
sys-
tolic volume is larger. Ventricular work is
equal to:
Work = Pressure
· Stroke Volume
= Force/Area ·
Volume = Force
· Length
or the area under the curve. The kinetic energy
of
the ejected blood can be ignored because it
repre-
sents 5% of the total energy and stays
constant
under most conditions. The area subtended by
the
pressure-volume loop increases as does the
work
in this case. Because the contractility of the
heart
represented by the upper curve remains
constant,
the end systolic volume also remains
constant.
Ventricular Volume
Mean
Aor
tic
Pressure
User Comments Add a comment…