SHolroydAtWeilCornellMedQatar/Endocrinology/VasopressinADH/ControlToWaterIntake

POINT!

Following water intake, the plasma osmolarity decreases, and negative feedback decreases (synthesis, secretion, and blood concentration of) ADH.

narrated video explanation

ファイル:ADHbaseline.jpg

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 water intake
Step 1: Water was taken. Water will enter the plasma and its osmolarity will decrease.

Step 2: Water intake will decrease plasma osmolarity. ADH, water channels, and reabsorption of water by the kidney will also decrease plasma osmolarity, having the same effect. Thus, with low plasma osmolarity following water intake, the plasma osmolarity-decreasing effect of ADH, water channels, and reabsorption would be too much.

video just after the decrease in ADH following water intake
Step 3: With too much effect of ADH, water channels, and reabsorption, the negative feedback decreases (synthesis, secretion, and blood concentration of) ADH.

Step 4: The water channels-increasing effect of ADH 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 the decrease in ADH caused by negative feedback following water intake
Step 5: The ratio of Na⁺ to water reabsorption by the kidney increases. This means plasma osmolarity increases. Also the decreased plasma osmolarity from water intake will increase returning to normal. Because a higher ratio of Na⁺ is reabsorbed the fluid left in the tubule now has a lower osmolarity. Also the decrease in the number of water channels decreases water reabsorption so there is more water. Overall, the urine becomes less concentrated (hypotonic) and high volume.

Challenge Quiz

1.

Following water intake, negative feedback increases decreases  正解! (synthesis, secretion, and blood concentration of) ADH.

2.

Following water intake, negative feedback increases decreases  正解! water channels channels in the kidney.

3.

Following water intake, negative feedback increases decreases  正解! water reabsorption by the kidney.

4.

Following water intake, negative feedback increases decreases  正解! urine volume.

5.

Following water intake, negative feedback increases decreases  正解! urine osmolarity.

6.

Following water intake, negative feedback increases decreases  正解! plasma osmolarity.

7.

Following water intake, the plasma osmolarity decreases increases  正解!. The effect would be the same as opposite to  正解! that of ADH, water channels and reabsorption of water by the kidney, which decreases increases  正解! plasma osmolarity. The effect of (synthesis, secretion, and blood concentration of) ADH would be too little too much  正解!. Negative feedback increases decreases  正解! (synthesis, secretion, and blood concentration of) ADH. This in turn increases decreases  正解! the production of water channels in the kidney causing increased decreased  正解! water reabsorption. Urine osmolarity will increase decrease  正解! while volume will increase decrease  正解!. This will decrease increase  正解! plasma osmolarity, returning to normal separating from normal  正解!.