Chapter 23 review questions Flashcards
Level 1:
Name the zones of the adrenal cortex and the primary hormones secreted in each zone.
Zona glomerulosa (aldosterone), zona fasciculata (glucocorticoids), zona reticularis (sex steroids, primarily androgens).
For (a) cortisol, (b) growth hormone, (c) parathyroid hormone, and (d) T3 and T4 and Draw the full control pathway and show feedback where appropriate. Do not use abbreviations.
List four conditions that are necessary for people to achieve their full growth. Include five specific hormones known to exert an effect on growth.
Conditions: adequate diet, absence of chronic stress, and adequate amounts of thyroid and growth hormones. Other important hormones: insulin, IGFs (somatomedins), and sex hormones at puberty.
Name the thyroid hormones. Which one has the highest activity? How and where is most of it produced?
Triiodothyronine (T3) and tetraiodothyronine (T4)
or thyroxine). T3 is the more active; most of it is made from T4 in peripheral tissues.
Define each of the following terms and explain its physiological significance:
a. melanocortins
b. osteoporosis
c. hydroxyapatite
d. mineralocorticoid
e. trabecular bone
f. POMC
g. epiphyseal plates
(a) Include ACTH (cortisol secretion) and MSH (not significant in humans). (b) Bone loss that occurs when bone reabsorption exceeds bone deposition. (c) The inorganic portion of bone matrix, mostly calcium salts. (d) Steroid hormones that regulate minerals, i.e., aldosterone. (e) Spongy bone, with an open latticework. (f) Pro-opiomelanocortin, inactive precursor to ACTH and other molecules. (g) Growth zones in long bones, comprised of cartilage.
List seven functions of calcium in the body.
Functions: blood clotting, cardiac muscle excitability and contraction, skeletal and smooth muscle contraction, second messenger systems, exocytosis, tight junctions, strength of bones and teeth.
Make a table showing the effects of cortisol, thyroid hormones, growth hormone, insulin, and glucagon on protein, carbohydrate, and lipid metabolism.
Level 2:
Mapping exercise: Create a reflex map with feedback loops for each of the following situations:
a. hypercortisolism from an adrenal tumor
b. hypercortisolism from a pituitary tumor
c. hyperthyroidism from a hormone-secreting thyroid tumor
d. hypothyroidism from a pituitary problem that decreases TSH synthesis
(a) CRH and ACTH low, cortisol high; (b) CRH low, ACTH and cortisol high; (c) TRH and TSH low, thyroid high; (d) TRH high, TSH and thyroid hormones low
Define, compare, and contrast or relate the terms in each set:
a. cortisol, glucocorticoids, ACTH, CRH
b. thyroid, C cell, follicle, colloid
c. thyroglobulin, tyrosine, iodide, TBG, deiodinase, TSH, TRH
d. somatotropin, IGF, GHRH, somatostatin, growth hormone–binding protein
e. giantism, acromegaly, dwarfism
f. hyperplasia, hypertrophy
g. osteoblast, osteoclast, chondrocyte, osteocyte
h. vitamin D, calcitriol, 1,25-dihydroxycholecalciferol, calcitonin, estrogen, PTH
Based on what you know about the cellular mechanism of action for
would you expect to see tissue response to this hormone within a few minutes or in more than an hour?
Thyroid hormones have intracellular receptors, so you expect 60–90 minute onset of action. However, effects on metabolic rate are apparent within a few minutes and are thought to be related to changes in ion transport across cell and mitochondrial membranes.
If average plasma [Ca2+] is 2.5 mmol/L, what is the concentration in mEq/L?
Equivalents = ion’s molarity x the number of charges/ion. 2.5 mmoles Ca2+ x 2 = 5 mEq Ca2+
Osteoclasts make acid (H+) from CO2 and H2O. They secrete the acid at their apical membrane and put bicarbonate into the ECF. Draw an osteoclast and diagram this process, including enzymes and the appropriate transporters on each membrane.
See Fig. 23.15. The cell uses carbonic anhydrase to make H+ from CO2 + H2O.
Apical membrane: H+ -ATPase secretes H+. Basolateral membrane secretes
with HCO3- with CL- -HCO3- antiporter.
Level 3:
Diabetic patients who have surgery, become sick, or are under other physiological stress are told to monitor their blood sugar carefully because they may need to increase their insulin dose temporarily. What is the physiological explanation behind this advice?
Physiological stress stimulates secretion of cortisol, which increases blood glucose. Increased insulin opposes this effect.
One diagnostic test to determine the cause of hypercortisolism is a dexamethasone suppression test. Dexamethasone blocks secretion of ACTH by the pituitary. The following table shows the results from two patients given a dexamethasone suppression test.
Can you tell from these results where the patients’ pathologies originate? Explain for each patient.
Normal response: dexamethasone –>
ACTH suppression —> decrease in cortisol. Patient A: no response to dexamethasone suggests adrenal hypersecretion that is insensitive to ACTH. Patient B: Dexamethasone decreases cortisol, suggesting that the problem is in the pituitary.
When blood test results came back last week, someone in the office spilled a cup of coffee on them, smearing the patient names and some of the numbers. One report shows elevated TSH levels, but the thyroid levels are so low they are unreadable. You have three charts waiting for test results on thyroid hormone levels. Your tentative diagnoses, based on physical findings and symptoms, for those three patients are:
Mr. A: primary hypothyroidism
Ms. B: primary hyperthyroidism
Ms. C: secondary hyperthyroidism
a. Can you tell whose results are on the smeared report, based on the TSH results and the tentative diagnosis?
b. Can you rule out any of the three people based on those same criteria? Explain.
Mr. A—elevated TSH. Ms. B—low TSH. Ms. C—elevated TSH. (a) Not possible to determine if the lab slip has the results of Mr. A or Ms. C without knowing the thyroid hormone levels. (b) Ms. B can be ruled out, because her TSH would be low if the tentative diagnosis is correct.
