Introduction: The endocrine system is the second greatest control system of the body and has many effects on the tissues and organs. The thyroid gland, which is a part of the endocrine system, releases a hormone that maintains metabolism. This hormone is thyroxine. Thyroxine production is controlled by thyroid stimulating hormone, which is released by the pituitary gland. TSH stimulates the thyroid gland to produce thyroxine. In this experiment, the effects of TSH and thyoxine on metabolic rate are investigated. Hypothesis: With the information given, we tested the effects of given hormones on the body by using virtual rats.
We expect to see a greater metabolic rate for the normal rat as opposed to the thyroidectomized rat. The hypox rat is expected to have the lowest metabolic rate. Metabolic rate will increase once thyroxine is injected. TSH will increase the metabolic rate of all the rats with the exception of the thyroidectomized rat. Rats that were injected with Propylthiouracil are expected to have a lower metabolic rate. Materials and Methods: Materials: syringe T-connector knob Weight scale Jar chamber Clamp Timer 3 lab rats ( Each were label Normal, Tx, and Hypox) Respiratory-manometer apparatus Nanometer ml 02 Soda lime Thyroxine.
TSH Propylthiouracil PhysioEx 6. 0, the human Anatomy & Physiology Lab Manuel and the computer Methods: Activity 1: Determining Baseline Metabolic Rates A normal rat was placed in the chamber and weighed. The clamp was then closed and the timer set to 1 minute. After 1 minute the manometer and syringe were connected and the clamp was opened. Air was injected into the tube until the fluid in each arm of the U-tube was level. The amount of O2 used in an hour was calculated and the metabolic rate for the normal rate was obtained. This process was repeated for the thyroidextomized rat and the hypopysectomized rat.
Activity 2: Determining the Effect of Thyroxine on Metabolic Rate A normal rat was injected with thyroxine and placed in the chamber and weighed. The clamp was then closed and the timer set to 1 minute. After 1 minute the manometer and syringe were connected and the clamp was opened. Air was injected into the tube until the fluid in each arm of the U-tube was level. The amount of O2 used in an hour was calculated and the metabolic rate for the normal rate was obtained. This process was repeated for the thyroidextomized rat and the hypopysectomized rat. Activity 3: Determining the Effect of TSH on Metabolic Rate.
A normal rat was injected with TSH and placed in the chamber and weighed. The clamp was then closed and the timer set to 1 minute. After 1 minute the manometer and syringe were connected and the clamp was opened. Air was injected into the tube until the fluid in each arm of the U-tube was level. The amount of O2 used in an hour was calculated and the metabolic rate for the normal rate was obtained. This process was repeated for the thyroidextomized rat and the hypopysectomized rat. Activity 4: Determining the Effect of Propylthiouracil on Metabolic Rate A normal rat was injected with Propylthiouracil and placed in the chamber and weighed.
The clamp was then closed and the timer set to 1 minute. After 1 minute the manometer and syringe were connected and the clamp was opened. Air was injected into the tube until the fluid in each arm of the U-tube was level. The amount of O2 used in an hour was calculated and the metabolic rate for the normal rate was obtained. This process was repeated for the thyroidextomized rat and the hypopysectomized rat. Results: Chart 1 Effects of Hormones on Metabolic Rate Normal Rat Thyroidectomized Rat Hypophysectomized Rat Baseline Weight Ml O2 used per hour Metabolic Rate 250. 8 grams 7. 2 ml 432 ml 1733 ml O2/kg/hr 245. 5 grams 6. 2 ml.
372 ml 1518 ml O2/kg/hr 244. 8 grams 6. 1 ml 366 ml 1495 ml O2/kg/hr With thyroxine Weight Ml O2 used per hour Metabolic Rate 249 . 9 grams 7. 9 ml 474 ml 1896 ml O2/kg/hr 245. 2 grams 7. 6 ml 456 ml 1861 ml O2/kg/hr 245. 5 grams 7. 5 ml 450 ml 1832 ml O2/kg/hr With TSH Weight Ml O2 used per hour Metabolic Rate 250. 9 grams 7. 8 ml 468 ml 1865 ml O2/kg/hr 245. 9 grams 6. 2 ml 372 ml 1512 ml O2/kg/hr 245 grams 7. 5 ml 450 ml 1836 ml O2/kg/hr With propylthiouracil Weight Ml O2 used per hour Metabolic Rate 249. 4 grams 6. 2 ml 372 ml 1491 ml O2/kg/hr 245. 1 grams 6. 0 ml 360 ml 1468 ml O2/kg/hr 244. 8 grams 6. 1 ml 366 ml 1495 ml O2/kg/hr.
Activity 1: Determining Baseline Metabolic Rates The baseline metabolic rate for the normal rat was 1733. 0 ml O2/kg/hr, the rate for the thyroidectomized rat was 1518. 0 ml O2/kg/hr, and the rate for the hypox rat was 1495. 0 ml O2/kg/hr. Baseline Normal Rat Thyroidextomized Rat Hypophysectomized Rat Weight 250. 8 245. 5 244. 8 ml O2 in 1min. 7. 2 6. 2 6. 1 ml O2 in 1 hour 432. 0 372. 0 366. 0 Metabolic Rate 1733. 0 1518. 0 1495. 0 Activity 2: Determining the Effect of Thyroxine on Metabolic Rate The metabolic rate was calculated after the rats had been injected with thyroxine. The metabolic rate for the normal rat was 1896.
0 ml O2/kg/hr, the rate for the thyroidectomized rat was 1861. 0 ml O2/kg/hr, and the rate for the hypox rat was 1832. 0 ml O2/kg/hr. With Thyroxine Normal Rat Thyroidextomized Rat Hypophysectomized Rat Weight 249. 9 245. 2 245. 5 ml O2 in 1min. 7. 9 7. 6 7. 5 Ml O2 in 1 hour 474. 0 456. 0 450. 0 Metabolic Rate 1896. 0 1861. 0 1832. 0 Activity 3: Determining the Effect of TSH on Metabolic Rate The metabolic rate was calculated after the rats had been injected with TSH. The metabolic rate for the normal rat was 1865. 0 ml O2/kg/hr, the rate for the thyroidectomized rat was 1512. 0 ml O2/kg/hr, and the rate for the hypox rat was 1836.
0 ml O2/kg/hr. With TSH Normal Rat Thyroidextomized Rat Hypophysectomized Rat Weight 250. 9 245. 9 245. 0 ml O2 in 1min. 7. 8 6. 2 7. 5 ml O2 in 1 hour 468. 0 372. 0 450. 0 Metabolic Rate 1865. 0 1512. 0 1836. 0 Activity 4: Determining the Effects of Propylthiouracil on Metabolic Rate The metabolic rate was calculated after the rats had been injected with Propylthiouracil. The metabolic rate for the normal rat was 1491 ml O2/kg/hr, the rate for the thyroidectomized rat was 1468 ml O2/kg/hr, and the rate for the hypox rat was 1495 ml O2/kg/hr. With Propylthiouracil Normal Rat Thyroidextomized Rat Hypophysectomized Rat Weight 249.
4 245. 1 244. 8 ml O2 in 1min. 6. 2 6. 0 6. 1 ml O2 in 1 hour 372. 0 360. 0 366. 0 Metabolic Rate 1491. 0 1468. 0 1495. 0 Discussion/Conclusions: The results for the baseline metabolic rate were as expected. The metabolic rates of the Tx and the Hypox rat were lower than the metabolic rate of the normal rat. The Tx rat could not produce thyroxine because it had no thyroid gland. The Hypox rat could not produce TSH which stimulates the thyroid to produce thyroxin. The results of the thyroxine metabolic rate were as expected. The injection of thyroxine increased the metabolic rate for all rats.
This is understandable as thyroxine is the most important hormone in maintaining metabolism. The injection provided the Tx rat with a source of thyroxine in place of the thyroid gland. The injection provided thryoxine for the Hypox rat in the absence of the pituitary gland to release TSH to stimulate the thyroid gland to produce thryoxine on its own. The results of the TSH metabolic rate were as expected. The metabolic rates for the normal and Hypox rats increased from the baseline rate. The injection of TSH would have had no effect on the Tx rat, as there was no thyroid gland to stimulate to release thyroxin.
The injection provided the Hypox rat with a source of TSH to stimulate production of thyroxin in the thyroid gland. Factors that may have changed the results of the experiment would be human error. If a step were missed, such as forgetting to clean the syringe after each use, it would affect the results. There may be a problem with the software and this would definitely affect the results.
References Marieb, Elain (2006). Human Anatomy & Physiology Laboratory Manual. 8th ed. Pearson Education, Inc. Zao, Peter (2006). PhysioEx Version 6. 0.