Exercise 4: Endocrine System Physiology: Activity 1: Metabolism and Thyroid Hormone Lab Report Pre-lab Quiz Results You scored 100% by answering 6 out of 6 questions correctly. 1. Which of the following statements about metabolism is false? You correctly answered: 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? You correctly answered: 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? You correctly answered: b. The hypothalamus primarily secretes tropic hormones that stimulate the secretion of other hormones. 11/15/11 page 1

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 : a. The normal rat will become hyperthyroidic and develop a goiter. Predict Question 3: What do you think will happen after you inject TSH into the three rats?

Your answer : b. The thyroidectomized 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 to display your results in the grid. You answered: 7. 2 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 to display your results in the grid. You answered: 1. 8 ml O2/kg/hr 2h. 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 to display your results in the grid. You answered: 6. 3 ml O2/hr 2i.

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 to display your results in the grid. 11/15/11 page 2 You answered: 1. 5 ml O2/kg/hr 3h.

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 to display your results in the grid. You answered: 6. 3 ml O2/hr 3i. 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 to display your results in the grid. You answered: 1. 5 ml O2/kg/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. uthyroid 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 thyroidectomized (Tx) rat is You correctly answered: a. hypothyroid 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 hypophysectomized (Hypox) rat is You correctly answered: a. hypothyroid 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) after the thyroxine injection. The normal rat is You correctly answered: c. yperthyroid 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) after the thyroxine injection. 11/15/11 page 3 The thyroidectomized (Tx) rat is You correctly answered: c. yperthyroid 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) after the thyroxine injection. The hypophysectomized (Hypox) rat is You correctly answered: c. hyperthyroid 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.

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) after the TSH injection. The normal rat is You correctly answered: c. hyperthyroid 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) after the TSH injection.

The thyroidectomized (Tx) rat is You correctly answered: a. hypothyroid 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) after the TSH injection. The hypophysectomized (Hypox) rat is You correctly answered: c. yperthyroid Which of the rats developed a goiter after injection with TSH (select all that apply)? Your answer: a. the normal rat Correct answer: a. the normal rat c. the hypophysectomized rat 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) after the PTU injection.

The normal rat is You correctly answered: a. hypothyroid 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) after the PTU injection. 11/15/11 page 4 The thyroidectomized (Tx) rat is You correctly answered: a. ypothyroid 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) after the PTU injection. The hypophysectomized (Hypox) rat is You correctly answered: a. hypothyroid Which of the rats developed a goiter after injection with PTU (select all that apply)? You correctly answered: a. he normal rat Experiment Data: Rat Normal Tx Hypox Normal Tx Hypox Normal Tx Hypox Normal Tx Hypox Weight (g) 250 246 245 250 246 245 250 246 245 250 246 245 ml O2/min 7. 2 6. 3 6. 3 8. 4 7. 7 7. 8 7. 9 6. 4 7. 9 6. 2 6. 4 6. 2 ml O2/hr 7. 2 6. 3 6. 3 504 462 468 474 384 474 372 384 372 BMR (ml O2/kg/hr) 1. 8 1. 5 1. 5 2016 1878 1910 1896 1561 1935 1488 1561 1518 Palpation No mass No mass No mass No mass No mass No mass Mass No mass Mass Mass No mass No mass Injected none none none Thyroxine Thyroxine Thyroxine TSH TSH TSH PTU PTU PTU 11/15/11 page 5

Post-lab Quiz Results You scored 0% by answering 0 out of 7 questions correctly. 1. How would you treat a thyroidectomized animal so that it functions like a “normal” animal? Your answer: b. Provide the animal TSH supplements. Correct answer: 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 loss Correct answer: d. decreased basal metabolic rate 3. An injection of thyroxine to an otherwise normal rat will cause which of the following? Your answer: c. igh levels of TSH secretion Correct answer: b. hyperthyroidism 4. Why didn’t any of the rats develop a goiter after thyroxine injection? You did not answer this question. Correct answer: 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?

Your answer: c. hyperthyroidism Correct answer: b. goiter development 7. Why did the normal rat develop a palpable goiter with the propylthiouracil injection? Your answer: a. The secretion of TSH was inhibited by the drug. Correct answer: d. The injection decreased the negative feedback mechanism on TSH. 11/15/11 page 6 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 2. Why did the metabolic rates differ between the normal rat and the surgically altered rats?

How well did the results compare with your prediction? Your answer: The thyroidectomized rat had a lower baseline metabolic rate beause the removal of its thyroid gland prevented it from producing any thyroxine 3. If an animal has been thyroidectomized, what hormone(s) would be missing in its blood? Your answer: TSH 4. If an animal has been hypophysectomized, what effect would you expect to see in the hormone levels in its body? Your answer: lower hormone levels 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 rat became hyper but didnt deveop a goiter 6. What was the effect of thyroxine injections on the thyroidectomized 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: all the rats became hyperthyroid but none developed a goiter 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: i was wrong the nomal rat became hyper but didnt develop a goiter 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: I was right but the normal rat also became hyperthyroidic and developed a goiter a) would be that it would increase it metabolism because theirbody will began to react! 9. What was the effect of TSH injections on the thyroidectomized rat’s BMR?

How does the BMR in this case compare with the normal rat’s BMR? Why was this effect observed? Your answer: 11/15/11 page 7 both the thyroidectomized rat and the normal becamer hyper and develpoed goiters becasue of the reaction 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: would be that it would increase it metabolism because theirbody will began to react! 11/15/11 page 8