The Effects of Thyroxine and TSH on the Metabolic Rate of Normal, Thyroidectomized, and Hypophysectomized Rats

6/28/2020 PhysioEx Exercise 4 Activity 1 PhysioEx Lab Report Exercise 4: Endocrine System Physiology Activity 1: Metabolism and Thyroid Hormone Name: Date: 28 June 2020 Session ID: 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: All of the energy from metabolism is ultimately stored in the chemical bonds of ATP. 2 Thyroxine is You correctly answered: the most important hormone for maintaining the metabolic rate and body temperature. 3 Thyroid-stimulating hormone (TSH) is You correctly answered: produced in the pituitary gland. 4 An injection of TSH to an otherwise normal animal will cause which of the following? You correctly answered: goiter development. 5 Thyrotropin-releasing hormone (TRH) is You correctly answered: secreted by the hypothalamus. 6 Which of the following statements is true? You correctly answered: The hypothalamus primarily secretes tropic hormones that stimulate the secretion of other hormones. Experiment Results Predict Questions 1 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: The hypophysectomized (Hypox) rat's BMR will be higher than the normal rat's BMR. 2 Predict Question 2: What do you think will happen after you inject thyroxine into the three rats? 1/14 6/28/2020 PhysioEx Exercise 4 Activity 1 Your answer: The normal rat will become hyperthyroidic and develop a goiter. 3 Predict Question 3: What do you think will happen after you inject TSH into the three rats? Your answer: The normal rat will become hyperthyroidic and develop a goiter. 4 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: The thyroidectomized rat will become hypothyroidic and develop a goiter. Stop & Think Questions 1 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 426 ml O 2/hr. 2 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1704 ml O 2/kg/hr. 3 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 384 ml O 2/hr. 4 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr 2/14 6/28/2020 PhysioEx Exercise 4 Activity 1 Enter the metabolic rate. You answered: 1567.35 ml O 2/kg/hr. 5 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 372 ml O 2/hr. 6 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1518.37 ml O 2/kg/hr. 7 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 hyperthyroid (high thyroid levels; BMR above 1800). The normal rat is You correctly answered: euthyroid. 8 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 hyperthyroid (high thyroid levels; BMR above 1800). The thyroidectomized (Tx) rat is You correctly answered: hypothyroid. 9 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 hyperthyroid (high thyroid levels; BMR above 1800). The hypophysectomized (Hypox) rat is You correctly answered: hypothyroid. 3/14 6/28/2020 PhysioEx Exercise 4 Activity 1 10 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 498 ml O 2/hr. 11 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1992 ml O 2/kg/hr. 12 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 468 ml O 2/hr. 13 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1910.20 ml O 2/kg/hr. 14 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 462 ml O 2/hr. 4/14 6/28/2020 PhysioEx Exercise 4 Activity 1 15 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1885.71 ml O 2/kg/hr. 16 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 hyperthyroid (high thyroid levels; BMR above 1800) after the thyroxine injection. The normal rat is You correctly answered: hyperthyroid. 17 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 hyperthyroid (high thyroid levels; BMR above 1800) after the thyroxine injection. The thyroidectomized (Tx) rat is You correctly answered: hyperthyroid. 18 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 hyperthyroid (high thyroid levels; BMR above 1800) after the thyroxine injection. The hypophysectomized (Hypox) rat is You correctly answered: hyperthyroid. 19 Which of the rats developed a goiter after injection with thyroxine? You correctly answered: None of the rats developed a goiter with this injection. 20 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour 5/14 6/28/2020 PhysioEx Exercise 4 Activity 1 Enter the oxygen consumption per hour. You answered: 480 ml O 2/hr. 21 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1920 ml O 2/kg/hr. 22 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 378 ml O 2/hr. 23 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1542.86 ml O 2/kg/hr. 24 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 468 ml O 2/hr. 25 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). 6/14 6/28/2020 PhysioEx Exercise 4 Activity 1 Metabolic rate = (ml O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1910.20 ml O 2/kg/hr. 26 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 hyperthyroid (high thyroid levels; BMR above 1800) after the TSH injection. The normal rat is You correctly answered: hyperthyroid. 27 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 hyperthyroid (high thyroid levels; BMR above 1800) after the TSH injection. The thyroidectomized (Tx) rat is You correctly answered: hypothyroid. 28 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 hyperthyroid (high thyroid levels; BMR above 1800) after the TSH injection. The hypophysectomized (Hypox) rat is You correctly answered: hyperthyroid. 29 Which of the rats did not develop a goiter after injection with TSH? You correctly answered: the thyroidectomized rat. 30 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 372 ml O 2/hr. 31 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). 7/14 6/28/2020 PhysioEx Exercise 4 Activity 1 Metabolic rate = (ml O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1488 ml O 2/kg/hr. 32 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 372 ml O 2/hr. 33 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1518.37 ml O 2/kg/hr. 34 Calculate the oxygen consumption per hour for this rat using the following equation. ml O 2 consumed/1 minute x 60 minutes/hour = ml O 2/hour Enter the oxygen consumption per hour. You answered: 384 ml O 2/hr. 35 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 O 2/hr)/(weight in kg) = ml O 2/kg/hr Enter the metabolic rate. You answered: 1567.35 ml O 2/kg/hr. 36 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 hyperthyroid (high thyroid levels; BMR above 1800) after the PTU injection. 8/14 6/28/2020 PhysioEx Exercise 4 Activity 1 The normal rat is You correctly answered: hypothyroid. 37 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 hyperthyroid (high thyroid levels; BMR above 1800) after the PTU injection. The thyroidectomized (Tx) rat is You correctly answered: hypothyroid. 38 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 hyperthyroid (high thyroid levels; BMR above 1800) after the PTU injection. The hypophysectomized (Hypox) rat is You correctly answered: hypothyroid. 39 Which of the rats developed a goiter after injection with PTU? You correctly answered: the normal rat. Experiment Data Rat Weight (g) ml O 2/min ml O 2/hr BMR (ml O2/kg/hr) Palpation Injected Normal 250 7.1 426.00 1704.00 No Mass none Tx 245 6.4 384.00 1567.35 No Mass none Hypox 245 6.2 372.00 1518.37 No Mass none Normal 250 8.3 498.00 1992.00 No Mass thyroxine Tx 245 7.8 468.00 1910.20 No Mass thyroxine thyroxine Hypox 245 7.7 462.00 1885.71 No Mass Normal 250 8.0 480.00 1920.00 Mass TSH Tx 245 6.3 378.00 1542.86 No Mass TSH Hypox 245 7.8 468.00 1910.20 Mass TSH Normal 250 6.2 372.00 1488.00 Mass PTU Tx 245 6.2 372.00 1518.37 No Mass PTU Hypox 245 6.4 384.00 1567.35 No Mass PTU Post-lab Quiz Results 9/14 6/28/2020 PhysioEx Exercise 4 Activity 1 You scored 100% by answering 7 out of 7 questions correctly. 1 How would you treat a thyroidectomized animal so that it functions like a "normal" animal? You correctly answered: Provide the animal T 4 supplements. 2 As a result of the missing hormone(s) in the hypophysectomized rat, what would be an expected symptom? You correctly answered: decreased basal metabolic rate. 3 An injection of thyroxine to an otherwise normal rat will cause which of the following? You correctly answered: hyperthyroidism. 4 Why didn't any of the rats develop a goiter after thyroxine injection? You correctly answered: 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? You correctly answered: 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: goiter development. 7 Why did the normal rat develop a palpable goiter with the propylthiouracil injection? You correctly answered: The injection decreased the negative feedback mechanism on TSH. 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 had the fastest basal metabolic rate with the BMR being 1704.00. 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: My prediction that the hypophysectomized rat's BMR will be higher than the normal rat's BMR was wrong. This is because organs play a very important role for the basal metabolic rate. The reason why metabolic rates differ between the normal rat and the surgically altered rats would be due to the fact that the thyroidectomized rat had its thyroid glands surgically removed while the hypophysectomized rat had its pituitary gland removed. The pituitary gland produces the 10/14 6/28/2020 PhysioEx Exercise 4 Activity 1 important hormone, thyroxine, to maintain metabolism and body heat. On the other hand, the pituitary gland controls the production of thyroxine or hypophysis, which secretes thyroidstimulating hormone (TSH). Without these important organs, the metabolic rates will differ between the normal rat and the surgically altered rats due to these missing endocrine glands. 3 If an animal has been thyroidectomized, what hormone(s) would be missing in its blood? Your answer: If an animal has been thyroidectomized, thyroxine will be missing in its blood. This is due to the fact that a thyroidectomized rat is a rat whose thyroid gland has been surgically removed. The thyroid gland secretes thyroxine, also known as tetraiodothyronine, or T4. 4 If an animal has been hypophysectomized, what effect would you expect to observe in the hormone levels in its body? Your answer: If an animal has been hypophysectomized, it means that its pituitary gland has been surgically removed. Therefore, there will be a low level of thyroid-stimulating hormone (TSH) since it cannot be secreted so there would not be anything to stimulate the thyroid to secrete thyroxine. 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: My prediction was partially correct where the normal rat will become hyperthyroidic but it did not develop a goiter. When thyroxine was injected into the normal rat, the BMR became 1992.00, hence hyperthyroidic. However, there were no palpation or a goiter did not develop. 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: My prediction that the normal rat will become hyperthyroidic and develop a goiter was only partially correct because the normal rat did indeed became hyperthyroidic but it did not develop a goiter after the injection of thyroxine. The effect of thyroxine injections on the thyroidectomized rat's BMR was that it increased to 1910.20. Although it is still lower than normal (BMR of 1992.00), it is still higher than the normal rat's (BMR of 1704.00) without drugs. Because the BMR was over 1800 thyroxine, the dose was too large. 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 11/14 6/28/2020 PhysioEx Exercise 4 Activity 1 large, too small, or just right? Your answer: My prediction that the normal rat will become hyperthyroidic and develop a goiter was only partially correct because the normal rat did indeed became hyperthyroidic but it did not develop a goiter after the injection of thyroxine. The effect of thyroxine injections on the hypophysectomized rat's BMR was that it increased to 1885.71. Although it is not as high as the thyroidectomized (BMR of 1910.20) or normal rats (BMR of 1992.00) with thyroxine, it is still higher than the normal rat's (BMR of 1704.00) without drugs. Because the BMR was over 1800 thyroxine, the dose was too large. 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: My prediction that the normal rat will become hyperthyroidic and develop a goiter was correct because the normal rat did indeed became hyperthyroidic with a BMR of 1920.00. It also developed a goiter after the injection of TSH due to its TSH receptors on the thyroid gland were excessively stimulated. 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: My prediction that the normal rat will become hyperthyroidic and develop a goiter was correct because the normal rat did indeed became hyperthyroidic with a BMR of 1920.00 and it developed a goiter after the injection of TSH. However, the effect of TSH injections on the thyroidectomzied rat's BMR was that it did not raise the BMR and was at a BMR of 1542.86 with no goiter was developed. It remained hypothyroidic with a BMR under 1600. The TSH injections acted as a negative feedback on the thyrotropin-releasing hormone (TRH) production, hence why the BMR became lower. 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: My prediction that the normal rat will become hyperthyroidic and develop a goiter was correct because the normal rat did indeed became hyperthyroidic with a BMR of 1920.00 and it developed a goiter after the injection of TSH. The effect of TSH injections on the hypophysectomized rat's BMR was similar to the normal rat's. The BMR was at 1910.20, which was close to the normal rat's 12/14 6/28/2020 PhysioEx Exercise 4 Activity 1 BMR of 1920.00. Therefore, the hypophysectomzied rat became hyperthyroidic and a goiter was developed. Although the number is not as high as the normal rat's (BMR of 1920.00), it is still higher than the normal rat's (BMR of 1704.00) without drugs. Because the BMR was over 1800, the dose of TSH in the syringe would be considered too large. 11 Part 4: Determining the Effect of Propylthiouracil on Metabolic Rate What was the effect of propylthiouracil (PTU) injections on the normal rat's BMR? Why did this rat develop a palpable goiter? Your answer: My prediction was partially correct that with the PTU injections, the thyroidectomized rat will indeed become hypothyroidic. However, no goiter was developed which I thought would have developed. The effect of propylthiouracil (PTU) injections on the normal rat's BMR was that it lowered the BMR from 1704.00 to 1488.00. Due to the injection decreasing the negative feedback mechanism on the thyroid-stimulating hormone, a palpable goiter was developed on the normal rat. 12 What was the effect of PTU 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: My prediction was partially correct that with the PTU injections, the thyroidectomized rat will indeed become hypothyroidic. However, no goiter was developed which I thought would have developed. The BMR of the thyroidectomized rat was 1518.37, which was a little higher than the normal rat's BMR of 1488.00. However, both numbers are still below 1600, categorizing the rats as hypothyroidic. The effect of the the propylthiouracil injections into the thyroidectomized rat was not apparent due to the absence of its thryoid gland to be affected. 13 What was the effect of PTU injections on the hypophysectomized rat's BMR? How does the BMR in this case compare with the normal rat's BMR? Why was this effect observed? Your answer: My prediction was partially correct that with the PTU injections, the thyroidectomized rat will indeed become hypothyroidic. However, no goiter was developed which I thought would have developed. The BMR of the hypophysectomized rat after the PTU injection was 1567.35, which was a little higher than the normal rat's BMR of 1488.00 with drugs but lower than the normal rat's BMR of 1704.00 without drugs. However, both BMR numbers on the rats with the PTU injections are still 13/14 6/28/2020 PhysioEx Exercise 4 Activity 1 below 1600, categorizing the rats as hypothyroidic. The effect of the the propylthiouracil injections into the thyroidectomized rat was not really evident due to the absence of its pituitary gland. 14/14