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BBIO 351: Principles of Anatomy & Physiology I
Quiz 3 (more endo)
Winter 2016
Name: __Dr. C__________________
[Each question was worth 5 points.]
1. You are a rodent endocrinologist. Your patient, Algernon, has been diagnosed with
hyperthyroidism based on elevated thyroxine (T4) levels in his blood. Describe two additional
tests/observations/analyses that you could do to rule in or rule out specific possible causes of this
hyperthyroidism.
Some of the many options here include….
 Check for goiter to see whether the thyroid itself is enlarged, and thus producing too
much hormone simply because it is larger than normal (e.g., due to a tumor).
 Check TRH levels. They will be high if an overactive hypothalamus is the primary
problem, but should be low otherwise.
 Check TSH levels. They will be high if an overactive pituitary is the primary problem,
but should be low otherwise.
 Check for the presence of thyroid-stimulating immunoglobulin (TSI), which can
chronically overstimulate the thyroid.
 Check whether the thyroid is inflamed. Inflammation could lead to leaky tissue in which
more hormone than usual leaks out of the thyroid into the blood.
2. For the graph at right, a person
eats a carbohydrate-rich meal at a
time of 2 hours. Complete the
graph with TWO lines: one
representing adipose tissue, and
one representing the pancreas. (In
other words, how does density of
GLUT4 in the cell membrane
vary over time in each of these
tissues?)
Adipose curve should go up after
eating, then fall again (3 points).
Pancreas curve should stay
essentially constant (2 points).
3. Explain how each of the following scenarios could be true (in different people): (A)
administration of propylthiourea (PTU) decreases iodine uptake by the thyroid gland; (B)
administration of PTU does not noticeably affect iodine uptake by the thyroid gland.
(A) This would be true in most people. PTU inhibits synthesis of thyroid hormone, so if less
hormone is made, less iodine is needed, and if less is needed, less is absorbed from the
blood.
(B) This would be true in someone who is missing a thyroid gland or has a severely
underactive thyroid. If little or no hormone is produced in the absence of PTU, PTU
cannot lower hormone production much further, and thus cannot decrease iodine uptake
much further because it is already close to 0.
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BBIO 351: Principles of Anatomy & Physiology I
Winter 2016
4. Which of the following statements are TRUE of thyroglobulin (Tg)? Check all that apply. [1
point apiece]
_yes_ a. It moves between follicular cells and colloid via endocytosis and exocytosis of vesicles.
_no_ b. It binds to T3 and T4 in the blood.
_yes_ c. It serves as a scaffold or workbench upon which T3 and T4 are made from precursors
monoiodothyronine and diiodothyronine.
_no_ d. It is a nucleic acid shaped kind of like RNA.
_no_ e. It pumps iodine ions from the blood into follicular cells.
5. A large, healthy person with no thyroid problems (weight: 100 kg) has basal metabolic rate of
500 mL O2 consumed per minute. A small person (weight: 50 kg) suffering from
hyperthyroidism has a basal metabolic rate of 400 mL O2 consumed per minute. Are these data
consistent with your expectations? Explain.
Full credit for answers like the following:
 The small person’s metabolic rate normalized to body mass (400/50 = 8 mL O2/kg/min)
is higher than the large person’s metabolic rate normalized to body mass (500/100 = 5
mL O2/kg/min). This is consistent with the smaller person being hyperthyroid. (Writing
out the math is helpful, but not required for full credit.)
3 points out of 5 for answers like the following:
 The small person is hyperthyroid, yet consumes less O2 than the other person. This is
surprising, because hyperthyroid people normally consume more O2 than others.
1.5 points out of 5 for answers like the following:
 The small person is hyperthyroid and consumes less O2 than the other person. This is
consistent with the general trend that metabolic rates are lower in hyperthyroid people.
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