To determine: The meaning of the term hypothalamic-hypophyseal portal system.
Introduction: Many of the hormones of the body are secreted into the blood and undergo rapid dilution as they diffuse through 5 L of the volume of the blood. The hypothalamic neurohormones which are bound for the anterior pituitary enter into a specially modified circulatory system known as a portal system. This occurs so that dilution can be avoided.
To determine: The importance of the hypothalamic-hypophyseal portal system.
Introduction: A portal system contains about two sets of capillaries joined in series with the help of small veins. The neurohormones of the hypothalamus invade the blood at the initial set of capillaries and enter directly into the second set of capillaries through the portal veins. At this place, they scatter out to extend to their target cells.
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Human Physiology: An Integrated Approach (7th Edition)
- Briefly explain the hypothalamo-hypophyseal portal system.arrow_forwardWhat is the role of the hypothalamic and hypophyseal portal vessels?arrow_forwardwhat are the specific names of the target cells of the anterior pituitary gland (adenohypophysis) that are regulated by hormones of the hypothalamus?arrow_forward
- During an in vitro experiment, it is found that glucocorticoids inhibit the growth of all neural processes, therefore controlling the morphologic characteristics of the chromaffin cells of the adrenal medulla. These modified neurons are most likely stimulated by which of the following mechanisms to release their secretory product? A) Acetylcholine release from sympathetic fibers B) Change in the rate of polymerization of metanephrine C) Decreased blood flow in cortical sinusoidal capillaries D) Downregulation of corticotropin-releasing factor E) Increased concentrations of endogenous chromogranins.arrow_forwardWhy are the eicosanoids often called “local hormones”?arrow_forward1)What tissue regulates both the adenohypophysis and the neurohypophysis? Does this tissue regulate lots of physiological functions? Give a few examples. 2) All of the following are directly controlled by a hormonal stimulus from the hypothalamus EXCEPT… a)GH, Growth hormone b) FSH c) Oxytocin. d) TSH, Thyroid Stimulating Hormone 3) How would a tumor in cells that produce TSH affect levels of TSH in the blood? increase / decrease / normal 4) How would this affect hormone secretion by the target cells of TSH? increase / decrease / normalarrow_forward
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- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning