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Name: Natalie Innecken

Exercise 4: Endocrine System Physiology: Activity 1: Metabolism and Thyroid Hormone Lab Report

Pre-lab Quiz Results

You scored 50% by answering 3 out of 6 questions correctly.

1. Which of the following statements about metabolism is false?

Your answer : a. Anabolism refers to chemical reactions that build larger, more complex molecules.Correct answer: d. All of the energy from metabolism is ultimately stored in the chemical bonds of ATP.

2. Thyroxine is

You correctly answered: c. the most important hormone for maintaining the metabolic rate and body temperature.

3. Thyroid-stimulating hormone (TSH) is

You correctly answered: b. produced in the pituitary gland.

4. An injection of TSH to an otherwise normal animal will cause which of the following?

Your answer : b. increased levels of TRH secretion

Correct answer: d. goiter development

5. Thyrotropin-releasing hormone (TRH) is

You correctly answered: a. secreted by the hypothalamus.

6. Which of the following statements is true?

Your answer : a. TRH travels from the hypothalamus to the thyroid gland via the hypothalamic-thyroid portal system.

Correct answer: b. The hypothalamus primarily secretes tropic hormones that stimulate the secretion of other hormones.

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Experiment Results

Predict Question:

Predict Question 1: Make a prediction about the basal metabolic rate (BMR) of the remaining rats compared with the BMR

of the normal rat you just measured.

Your answer : b. The hypophysectomized (Hypox) rat's BMR will be higher than the normal rat's BMR.

Predict Question 2: What do you think will happen after you inject thyroxine into the three rats?

Your answer : d. The normal rat will become hyperthyroidic but will not develop a goiter.

Predict Question 3: What do you think will happen after you inject TSH into the three rats?

Your answer : a. The normal rat will become hyperthyroidic and develop a goiter.

Predict Question 4: Propylthiouracil (PTU) is a drug that inhibits the production of thyroxine by blocking the attachment of

iodine to tyrosine residues in the follicle cells of the thyroid gland (iodinated tyrosines are linked together to form thyroxine).

What do you think will happen after you inject PTU into the three rats?

Your answer : b. The thyroidectomized rat will become hypothyroidic and develop a goiter.

Stop & Think Questions:

1h. Calculate the oxygen consumption per hour for this rat using the following equation.

ml O2 consumed/1 minute x 60 minutes/hour = ml O2/hour

Enter the oxygen consumption per hour in the field below and then click Submit Datato display your results in the Lab

Report.

You answered: 426 ml O2/hr

1i. Now that you have calculated the oxygen consumption per hour for this rat, you can calculate the metabolic rate per

kilogram of body weight with the following equation (note that you need to convert the weight data from grams to kilograms

to use this equation).

Metabolic rate = (ml O2/hr)/(weight in kg) = ml O2/kg/hr

Enter the metabolic rate in the field below and then click Submit Datato display your results in the Lab Report.

You answered: 1704 ml O2/kg/hr




Report.






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You answered: 1518.37 ml O2/kg/hr




Report.You answered: 378 ml O2/hr







Judging from their basal metabolic rates (an indicator of thyroid function), categorize the rats as hypothyroid (low thyroid

levels; BMR below 1600), euthyroid ("good," or normal, thyroid levels; BMR = 1650-1750), or hyperthryoid (high thyroid

levels; BMR above 1800).

The normal rat is

You correctly answered: b. euthyroid




The thyroidectomized (Tx) rat is

You correctly answered: a. hypothyroid




The hypophysectomized (Hypox) rat is


4c. Calculate the oxygen consumption per hour for this rat using the following equation.



Report.


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4d. Now that you have calculated the oxygen consumption per hour for this rat, you can calculate the metabolic rate per









Report.










Enter the oxygen consumption per hour in the field below and then click Submit Datato display your results in the LabReport.










levels; BMR above 1800) after the thyroxine injection.

The normal rat is

You correctly answered: c. hyperthyroid

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levels; BMR above 1800) after the thyroxine injection.




levels; BMR below 1600), euthyroid ("good," or normal, thyroid levels; BMR = 1650-1750), or hyperthryoid (high thyroidlevels; BMR above 1800) after the thyroxine injection.



Which of the rats developed a goiter after injection with thyroxine (select all that apply)?

You correctly answered: d. None of the rats developed a goiter with this injection.




Report.











Report.







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Report.








Judging from their basal metabolic rates (an indicator of thyroid function), categorize the rats as hypothyroid (low thyroidlevels; BMR below 1600), euthyroid ("good," or normal, thyroid levels; BMR = 1650-1750), or hyperthryoid (high thyroid

levels; BMR above 1800) after the TSH injection.

The normal rat is





The thyroidectomized (Tx) rat isYou correctly answered: a. hypothyroid






Which of the rats developed a goiter after injection with TSH (select all that apply)?

You correctly answered: a. the normal rat c. the hypophysectomized rat




Report.


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Report.










Enter the oxygen consumption per hour in the field below and then click Submit Datato display your results in the LabReport.










levels; BMR above 1800) after the PTU injection.

The normal rat is


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levels; BMR above 1800) after the PTU injection.




levels; BMR below 1600), euthyroid ("good," or normal, thyroid levels; BMR = 1650-1750), or hyperthryoid (high thyroidlevels; BMR above 1800) after the PTU injection.



Which of the rats developed a goiter after injection with PTU (select all that apply)?

You correctly answered: a. the normal rat

Experiment Data:

Rat Weight (g) ml O2/min ml O2/hr BMR(ml O2/kg/hr)

Palpation Injected

Tx 245 6.2 372.00 1518.37 No Mass none

Normal 250 7.1 426.00 1704.00 No Mass none

Hypox 244 6.3 378.00 1549.18 No Mass none

Normal 250 8.4 504.00 2016.00 No Mass thyroxine

Tx 245 7.7 462.00 1885.71 No Mass thyroxine

Hypox 244 7.8 468.00 1918.03 No Mass thyroxine

Normal 250 7.9 474.00 1896.00 Mass TSH

Tx 245 6.2 372.00 1518.37 No Mass TSH

Hypox 244 7.8 468.00 1918.03 Mass TSH

Normal 250 6.3 378.00 1512.00 Mass ptuTx 245 6.4 384.00 1567.35 No Mass ptu

Hypox 244 6.3 378.00 1549.18 No Mass ptu

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Post-lab Quiz Results

You scored 57% by answering 4 out of 7 questions correctly.

1. How would you treat a thyroidectomized animal so that it functions like a "normal" animal?

You correctly answered: c. Provide the animal T4 supplements.

2. As a result of the missing hormone(s) in the hypophysectimized rat, what would be some expected symptoms?

Your answer: a. unexplained weight lossCorrect answer: d. decreased basal metabolic rate

3. An injection of thyroxine to an otherwise normal rat will cause which of the following?

You correctly answered: b. hyperthyroidism

4. Why didn't any of the rats develop a goiter after thyroxine injection?

You correctly answered: a. In all cases, TSH levels were not elevated by the thyroxine injection.

5. Why did the normal rat develop a palpable goiter with the TSH injection?

Your answer: a. The TSH receptors in the hypothalamus were overstimulated.

Correct answer: c. The TSH receptors on the thyroid gland were excessively stimulated.

6. An injection of propylthiouracil to an otherwise normal animal will cause which of the following?

You correctly answered: b. goiter development

7. Why did the normal rat develop a palpable goiter with the propylthiouracil injection?

Your answer: b. The amount of T4 secretion by the thyroid gland became excessive.

Correct answer: d. The injection decreased the negative feedback mechanism on TSH.

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Review Sheet Results

1. Part 1: Determining the Basal Metabolic Rates

Which rat had the fastest basal metabolic rate (BMR)?

Your answer:

The normal rat, for it did not have a missing pituitary gland or thyroid glnad.

2. Why did the metabolic rates differ between the normal rat and the surgically altered rats? How well did the resultscompare with your prediction?

Your answer:

The normal rat had the highest BMR due to its retention of the glands which are required to stimulate and regulate the

release of thyroid hormones.

3. If an animal has been thyroidectomized, what hormone(s) would be missing in its blood?

Your answer:

The animal would be missing the triiodythronine and thyroxine.

4. If an animal has been hypophysectomized, what effect would you expect to see in the hormone levels in its body?

Your answer:One would expect the TSH to be missing due to the missing or removal of the pituitary gland.

5. Part 2: Determining the Effect of Thyroxine on Metabolic Rate

What was the effect of thyroxine injections on the normal rat's BMR?

Your answer:

The effect the thyroxine injection had on the normal rat was that it increased the metabolic rate but it was not enough to

develop a goiter.

6. What was the effect of thyroxine injections on the thyroidectomized rat's BMR? How does the BMR in this case compar

with the normal rat's BMR? Was the dose of thyroxine in the syringe too large, too small, or just right?Your answer:

The effect of thyroxine injections on the Tx rat's BMR was that it increased. However the BMR was still lower than the

normal rats BMR, for the dosage was lower.

7. What was the effect of thyroxine injections on the hypophysectomized rat's BMR? How does the BMR in this case

compare with the normal rat's BMR? Was the dose of thyroxine in the syringe too large, too small, or just right?

Your answer:

The effect of thyroxine injections on the hypophysectomized rat's BMR was that it also increased. And its BMR though still

remained lower than the normal rat's since its dosage was lower.

8. Part 3: Determining the Effect of TSH on Metabolic Rate

What was the effect of thyroid-stimulating hormone (TSH) injections on the normal rat's BMR?

Your answer:

TSH's effect on the normal rat's BMR was that it increased.

9. What was the effect of TSH injections on the thyroidectomized rat's BMR? How does the BMR in this case compare wit

the normal rat's BMR? Why was this effect observed?

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Your answer:

There was no TSH effect on the thyroidectomized rat for it did not have a thyroid gland to stimulate.

10. What was the effect of TSH injections on the hypophysectomized rat's BMR? How does the BMR in this case compare

with the normal rat's BMR? Was the dose of TSH in the syringe too large, too small, or just right?

Your answer:

The effect of TSH on the rat's BMR was that it increased.The BMR was just below the normal rat's and the syringe amount

was too small.

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203010641-PEX-04-01.pdf