Thyroxine is a peptide hormone, but its mechanism is different from other peptide hormones. Which of the following statements is true concerning this difference?
A) It causes positive feedback.
B) It does not require a second messenger to effect a response.
C) It is very specific in the cell type it targets.
D) It is a stimulant of cellular metabolism and targets all cells.
Answer: B
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The Endocrine System
- What ion is sometimes used as a second messenger of amino acid based hormones?
- How do glucocorticoids enable the body to deal appropriately with stress?
- Which of the following organs is affected by thyroid hormone in adults?
- A man has been told that he is not synthesizing enough follicle-stimulating hormone (FSH), and for this reason he may be unable to father a child. Choose the correct statement to explain this problem.
- Eicosanoids do not include ________.
- In circumstances where the body requires prolonged or increased levels of a hormone, the DNA of target cells will specify the synthesis of more receptors on the surface of the cells of the target organ. This is known as ________.
- Which organ does not have hormone production?
- The only amine hormone to act like a steroid is ________.
- Aldosterone ________.
- Which of the following is true about calcium homeostasis?
- ACTH ________.
- Regulating hormones from the hypothalamus ________.
- Cellular responses to hormones that initiate second-messenger systems include ________.
- Which of the following would be associated with the action of steroids on cells?
- Which of the following is not a steroid-based hormone?
- The most important regulator of electrolyte concentrations in extracellular fluids is ________.
- Leptin is secreted by ________.
- Mineralocorticoid is to aldosterone as glucocorticoid is to ________.
- Which organ is responsible for synthesizing ANP?
- The parathyroid glands maintain adequate levels of blood calcium. This is accomplished through ________.
- The major targets of growth hormone are ________.
- One of the least complicated of the endocrine control systems directly responds to changing blood levels of ions and nutrients. Which of the following describes this mechanism?
- When it becomes necessary to enlist the fight-or-flight response, a hormone that is released during the alarm phase of the general adaptation syndrome is ________.
- Thyroid hormone (a small iodinated amine) enters target cells in a manner similar to ________.