Endocrine System Physiology: Computer Simulation
The following questions refer to Activity 1: Determining Baseline Metabolic Rates.
1. Which rat had the fastest baseline metabolic rate? -------------------------The normal rat
2. Compare the baseline metabolic rates for the thyroidectomized rat and the normal rat and explain your results. The thyroidectomized rat had a lower baseline metabolic rate beause the removal of its thyroid gland prevented it from producing any thyroxine.
3. Compare the baseline metabolic rates for the hypophysectomized rat and the normal rat and explain your results. The hypophysectomized rat had a lower baseline metabolic rate because removal of the pituitary gland, or hypophysis, prevented TSH production.
The following questions refer to Activity 2: Determining the Effect of Thyroxine on Metabolic Rate. 4. What effect did administering thyroxine have on each of the rats? The baseline metabolic rate increased in each rat.
5. Explain why thyroxine had these effects. The effect of thyroxine is to increase baseline metabolic rate.
The following questions refer to Activity 3: Determining the Effect ofTSH on Metabolic Rate. 6. Was there a change in the metabolic rate of the thyroidectomized rat with the administration ofTSH? Explain your results. __ No; there was no thyroid gland to be stimulated.
7. Did the results for the thyroidectomized
rat indicate hyperthyroidism
The following questions refer to Activity 4: Determining the Effect of Propylthiouracil on Metabolic Rate.
8. Describe the effect of administering propylthiouracil on each of the rats, and explain why it had this effect. It decreased BMR in normal and hypophysectomized rats because propylthiouracil blocks the attachment of iodine to tyrosine residues and
interferes with the conversion of thyroxine to triiodothyronine.
9. Do you think the drug propylthiouracil is used to treat hypothyroidism or hyperthyroidism? Explain your answer. Hyperthyroidism; propylthiouracil is antagonistic to thyroxine and will tend to decrease the effects of thyroxine.
Hormone Replacement Therapy
The following questions refer to Activity 5: Hormone Replacement Therapy. 10. Explain why ovariectomized rats were used in this experiment and correlate this to their baseline T score. Ovariectomized rats were used because they do not produce estrogen. Their baseline T score shows that they have already developed osteoporosis.
11. Recap your predictions regarding the effects of calcitonin and estrogen on bone density and why you made those predictions. Student answers will vary.
12. Why was one of the ovariectomized rats injected with saline? The saline rats are negative controls. Saline should have no effect on bone density. The rats therefore should not show a change in vertebral bone density with saline injection.
13. What effect did the administration of estrogen injections have on the estrogen-treated rat? an increase in vertebral bone density.
14. What effect did the administration of calcitonin injections have on the calcitonin-treated effect on vertebral bone density.
rat? Calcitonin injections had no
15. How did your results compare to your predictions?
Student answers will vary. In general, their prediction for calcitonin probably
won't match because they will expect a change with the calcitonin injections.
Insulin and Diabetes
The following question refers to Activity 6: Obtaining a Glucose Standard Curve. 16. What is a glucose standard curve, and how can you use this tool to determine a concentration of glucose? A glucose standard curve is a point of reference for converting optical density into glucose readings by comparing optical density readings for known amounts of glucose to unkown amounts.
Review Sheet 28B