Endocrine System Physiology

Only available on StudyMode
  • Download(s) : 249
  • Published : May 4, 2011
Open Document
Text Preview
Endocrine System Physiology
Hormones & Metabolism

A normal rat's MR(metabolic rate) is normal or faster than the thyroidectomized or hypophysectomized because it produces thyroxine normally.

A thyroidectomized rat's MR goes down because there is no thyroid to produce thyroxine.
A hypophysectomized rat's MR goes down because there is no pituitary gland to produce TSH which stimulates thyroxine production.
w/thyroxine:

A normal rat's MR(metabolic rate) goes up because it will ALWAYS increase with thyroxine.

A thyroidectomized rat's MR goes up because it will ALWAYS increase with thyroxine.

A hypophysectomized rat's MR goes up because it will ALWAYS increase with thyroxine.

w/TSH:

A normal rat's MR(metabolic rate) will go up because the TSH will increase the production of thyroxine which then always increases MR.

A thyroidectomized rat's MR does not have much change because there is no thyroid to stimulate.

A hypophysectomized rat's MR goes up because the injected TSH made up for the lost TSH when the pituitary gland was removed. The TSH spurs the production of thyroxine which again ALWAYS increases MR.

w/PTU (propylthiouracil):

A normal rat's MR(metabolic rate) goes down because the PTU prevents the thyroid from producing too much thyroid hormone. It reduces the thyroid's activity and therefore slows down MR. This is used for Hyperthyroidism.

A thyroidectomized rat's MR does not have much change because there is no thyroid there to reduce the activity.

A hypophysectomized rat's MR does not have much change either because it cannot start the HTP axis.
tracking img