Endocrine System

Created by torrio22 

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Metabolism

All biochemical reactions occurring in the body.
involves catabolism and anabolism.

Thyroxine

Most important hormone in maintaining metabolism and body heat.
In thyroid gland.

Pituitary gland

Controls the production of thyroxine and secretes TSH (thyroid-stimulating hormone). TSH is carried by the blood to the thyroid gland and causes the thyroid to produce more thyroxine.

Thyroidectomy

Removal of the thyroid.

Hypophysectomy

Removal of the pituitary gland.

Hypophysis

Pituitary gland.

rat with fastest baseline metabolic rate

normal rat

Effect of thyroxine injections on the normal rat's BMR

The normal rat was hyperthyroidic because the thyroxine increases the metabolic rate but it did not develop goiter.

What was the effect of administering thyroxine on each of the rats?

The baseline metabolic rate increased in each rat.

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

The effect of TSH was to increase the normal rat's BMR.

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?

There was no effect on the thyroidectomized rat's BMR with the injection of TSH because there was no thyroid gland to stimulate. This indicated hypothyroidism.

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?

The hypophysectomized rat BMR increased with TSH. The BMR was just below the normal rat but still lower. the syringe amount was a little too low.

What was the effect of propylthiouracil (PTU) injections on the normal rat's BMR? Why did this rat develop a palpable goiter?

The effect of PTU injections on the normal rat was to decrease the BMR. The palpable goiter was due to the buildup of the precursors to thyroxine.

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?

The effect of PTU injections on the thyroidectomized rat was not visible because there was no thyroid gland to be affected.

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?

The effect of PTU injections on the hypophysectomized rat was not visible because the rat is missing the pituitary gland.

Compare the baseline metabolic rates for the thyroidectomized rat and the normal rat and explain your results.

The thyroidectomized rat had a lower baseline metabolic rate beause the removal of its thyroid gland prevented it from producing any thyroxine.

Compare the baseline metabolic rates for the hypophysectomized rat and the normal rat and explain your results. The hypophysectomized rat had a lower baseline metabolic rate because removal of the pituitary gland, or hypophysis, prevented TSH production.

Compare the baseline metabolic rates for the hypophysectomized rat and the normal rat and explain your results. The hypophysectomized rat had a lower baseline metabolic rate because removal of the pituitary gland, or hypophysis, prevented TSH production.

Explain why thyroxine had these effects.

The effect of thyroxine is to increase baseline metabolic rate.

Describe the effect of administering propylthiouracil on each of the rats, and explain why it had this effect.

It decreased BMR in normal and hypophysectomized rats because propylthiouracil blocks the attachment of iodine to tyrosine residues and interferes with the conversion of thyroxine to triiodothyronine.

Do you think the drug propylthiouracil is used to treat hypothyroidism or hyperthyroidism? Explain your answer.

Hyperthyroidism; propylthiouracil is antagonistic to thyroxine and will tend to decrease the effects of thyroxine.

Propylthiouracil

Inhibits the production of thyroxine by blocking the attachment of iodine to the amino acid tyrosine and interfering with the conversion of thyroxine to triiodothyronine.

If all groups were fed the same amount of food, which group would have the greatest weight gain? The least?

The thyroidectomized rat would have the greatest weight gain. The normal rat would have the least.

What effect would acclimation to cold have on thyroxine production?

It would cause an increase in thyroxine production.

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