Case #2: On a particularly busy day, a student taking Anatomy and Physiology I does not have anything to drink from 9:30 am until 6:30 pm. Osmoreceptors in the brain detect the decreased level of water in the blood. These receptors send a signal to the hypothalamus/posterior pituitary, which stimulates the release of antidiuretic hormone (ADH). This hormone acts on the nephron tubules and collecting ducts in the kidney to increase reabsorption of water, which returns that water to the blood. This retention of water has the additional effect of decreasing urinary output. As the fluid levels in the blood stabilize, the release of ADH ends. 1. What is the variable monitored by this loop? 2. What is the stimulus? 3. What is the control center? 4. What is the effector? 5. What is the efferent pathway? 6. This is an example of __ (positive / negative) feedback. How could you tell?
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The variable monitored by this loop is the level of water in the blood. Show more…
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ADH (Anti-diuretic hormone) is important in maintaining homeostasis in mammals. ADH is released from hypothalamus in response to high tissue osmolarity (=less water in blood). In response to ADH, the collecting duct and distal tubule in the kidney become more permeable to water, which increases water reabsorption into capillaries. The amount of hormone released is controlled by a negative feedback loop. Based on the model presented, what is the relationship between ADH release, osmolarity and production of urine? As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine As tissue osmolarity rises, less ADH is released, causing less water to be excreted as urine As tissue osmolarity rises, more ADH is released, causing more water to be excreted as urine As tissue osmolarity rises, less ADH is released, causing more water to be excreted as urine Two of the above
Nayan G.
In mammals, an increase in the concentration of sodium in the blood triggers the release of antidiuretic hormone (ADH) from the pituitary gland. As the concentration of sodium in the blood returns to previous levels, the release of ADH from the pituitary gland is reduced. Based on the information presented, what describes the most likely role of ADH in maintaining blood osmolarity?
Sri K.
Antidiuretic hormone (ADH) increases the permeability of the collecting ducts to water, facilitates water reabsorption. As a result, urine volume _____ and blood volume _____.
Adi S.
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