SHolroydAtWeilCornellMedQatar/Endocrinology/VasopressinADH/ControlToWaterIntake
| When plasma osmolarity is decreased by intake of water, the negative feedback decreases (synthesis, secretion and blood concentration of) ADH. |
video prior to water intake
Prior to water intake, we assume our subject is in homeostasis with normal plasma and urine osmolarities and volumes.
video just after drinking
Steps 1 and 2: Water was taken. Water will enter the plasma and its osmolarity will decrease. Both intake of water and the ADH/water channels/reabsorption of water by the kidney will decrease plasma osmolarity, having the same effect. Thus, in this case with low plasma osmolarity, the effect of ADH/water channels/reabsorption would be too much.
video just after ADH decreased responding to drinking
Steps 3 and 4: With too much effect of ADH/water channels/reabsorption, the negative feedback decreases (synthesis, secretion, and blood concentration of) ADH. The ADH-facilitating effect on the water channels will decrease, decreasing the number of water channels. This decreases the reabsorption of water by the kidney.
video showing the changes in plasma and urine after ADH decreased responding to drinking
Step 5: The ratio of Na+ to water reabsorption by the kidney increases. This means plasma osmolarity increases. The decreased plasma osmolarity from intake of water will increase returning to normal.
Because a higher ratio of Na+ is reabsorbed the fluid left in the tubule now has a lower osmolarity. The decrease in the number of water channels decreases water reabsorption so there is more water. Overall the urine becomes less concentrated and high volume.
Challenge Quiz
After intake of water, negative feedback increases decreases ADH.
After intake of water, negative feedback increases decreases water channels channels in the kidney.
After intake of water, negative feedback increases decreases water reabsorption by the kidney.
After intake of water, negative feedback increases decreases urine volume.
After intake of water, negative feedback increases decreases urine osmolarity.
After intake of water, negative feedback increases decreases plasma osmolarity.
When you drink water the plasma osmolarity decreases increases . This has the effect of increasing decreasing (synthesis, secretion, and blood concentration of) ADH. This in turn increases decreases the production of water channels by the kidney causing increased decreased water reabsorption. Urine osmolarity will increase decrease while volume will increase decrease . This will decrease increase plasma osmolarity, returning to normal separating from normal .