Physiology

2. As it turns out, the press release you read about on your in-class exam that revealed Cookie Monster as a type II diabetic was incorrect. In fact, the entire story was fabricated by Oscar the Grouch, as he was jealous of Cookie Monster’s popularity. As it turns out, Cookie Monster is just fine, and in fact, is in perfect health.

This raises another question – how has Cookie Monster NOT developed type II diabetes after spending 40 years eating nothing but massive amounts of sugar-rich cookies. After taking in very high sugar levels for years and years, we’d expect to see desensitization to insulin, yet we see no outward manifestation of this. Propose FOUR ways by which this phenomenon could occur. For each proposed idea, offer a mechanistic explanation using the means / pattern by which blood sugar levels are regulated. Be specific and descriptive. Assume we are dealing with the “old school” Cookie Monster who eats only Cookies and not the one who switched to eating veggies.
 3. While shadowing a physician in the Endocrinology division of Johns Hopkins University Hospital, you attend the divisional meeting in which all medical staff gathers to discuss the most difficult of patient cases. At this meeting, the staff discusses a patient who shows the following lab results:

CRH – Normal

ACTH – Elevated

Cortisol – Low

Based on the above lab results, your understanding of the trophic cascade by which cortisol is released, and your understanding of the endocrine system in general, propose a plausible mechanism that would explain the pathology given above. Be specific and descriptive, and offer a detailed explanation of how your proposal explains the observed phenomenon.
 4. Like cortisol, thyroid hormone is under trophic control of the hypothalamic-anterior pituitary axis. The hypothalamus releases thryrotrophic releasing hormone (TRH) which, upon delivery to the anterior pituitary via the hypopheseal portal system, triggers the release of thyroid stimulating hormone (TSH) from the anterior pituitary. TSH then stimulates the thyroid (an endocrine gland located just below the Adam’s apple, or larynx) to release thyroid hormones. As was the case with the release of cortisol, both the trophic hormones (TRH and TSH) and the peripheral hormone (thyroid hormone) serve as feedback signals.

A goiter is an enlargement of the thyroid gland, sometimes by as much as 10 times, as shown in the pictures below.

Goiters result from elevated TSH levels. With which condition – elevated or depressed circulating thyroid hormone levels – would you expect goiters to be associated? Why? Be very specific and descriptive. NOTE: The answer does not require detailed knowledge of the action or nature of thyroid hormone, only of the way hormones under control of the hypothalamic-anterior pituitary axis work.