Metabolism and Thyroid Hormone Lab (endocrine system)

Question 1

hypothyroid

Answer 1

low thyroid levels

bmr below 1600

Question 2

euthyroid

Answer 2

good, normal thyroid levels

bmr = 1600-1750

Question 3

hyperthyroid

Answer 3

high thyroid levels

bmr above 1800

Question 4

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

Answer 4

The normal rat that was injected with thyroxine

Question 5

Why did the metabolic rates differ between the normal rat and the surgically altered rats? How well did the results compare with your prediction?

Answer 5

The Tx rats had their thyroid removed and Hypox rats had their pituitary gland removed. The lack of these organs resulted in lower BMRs due to lack of production of thyroxine.

Question 6

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

Answer 6

thyroxine

Question 7

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

Answer 7

metabolic rate and body temp would decrease

Question 8

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

Answer 8

The metabolic rate increased

Question 9

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?

Answer 9

The metabolic rate increased for the thyroidectomized rat. Although the BMR decreased it was still lower than the normal rat’s BMR. The dose of thyroxine was just right because it did not cause the thyroidectomized rat to develop a goiter.

Question 10

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?

Answer 10

The metabolic rate of the hypophysectomized rat increased. The BMR of the hypophysectomized rat increased but not as high as the normal rat’s BMR. The dose of thyroxine was just right because it did not cause the hypophysectomized rat to develop a goiter.

Question 11

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

Answer 11

The thyroidectomized rat will become hyperthyroidic and develop a goiter.

Question 12

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?

Answer 12

The thyroidectomized rat’s BMR decreased. The normal rat’s BMR is much higher than the thyroidectomized rat’s BMR. Without a thyroid to stimulate, which was removed in the thyroidectomized rat, TSH is not very effective

Question 13

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?

Answer 13

The hypophysectomized rat’s BMR increased. Although the BMR of the hypophysectomized rat increased it was still lower than the normal rat’s BMR. The dosage was too large because the hypophysectomized rat developed a goiter.