Review Sheet
Exercise 4
Endocrine System Physiology
Name: Kelly E. Fischer Lab Time/Date: 7:00 PM/Wednesday
Activity 1 Metabolism and Thyroid Hormone
Part 1
1 Which rat had the fastest basal metabolic rate (BMR)?
The normal rat had the faster basal metabolic rate, because it was not missing its pituitary gland or its thyroid gland.
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?
The normal rat has the highest BMR because it has the glands 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?
Triiodothyronine and thyroxine.
4 If an animal has been hypophysectomized, what effect would you expect to see in the hormone levels in its body?
For the hypophysectomized rat, TSH would be missing due to the missing pituitary gland.
Part 2
5 What was the effect of thyroxine injections on the normal rat’s BMR?
The levels were a little off. The normal rat was hyperthyroidic because the thyroxine increases the metabolic rate but it did not develop 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?
The BMR increased for the thyroidectomized rat with the thyroxine injections. The BMR was still a little bit under the normal rat's BMR with thyroxine. The dose was too low.
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?
The BMR increased for the hypophysectomized rat with the thyroxine injections. The BMR was still a little bit under the normal rat's BMR with thyroxine. The dose was too