SHolroydAtWeilCornellMedQatar/Endocrinology/VasopressinADH/ControlToWaterIntake
| Intake of water will decrease plasma osmolarity. This will in turn lead to a decrease in the synthesis, secretion and blood concentration of ADH. |
video prior to drinking
Prior to drinking 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 (the 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. So overall the urine becomes less concentrated and high volume.
Challenge Quiz
<GIFT> //LEVEL:2 //RAND The negative feedback response to an increased intake of water is a(n) {increase~=decrease} of ADH secretion.
//LEVEL:3 //RAND
The negative feedback response to an increased intake of water is a(n) {increase~=decrease} of water channels channels in the kidney.
//LEVEL:2 //RAND The negative feedback response to an increased intake of water is a(n) {increase~=decrease} in water reabsorption by the nephron.
//LEVEL:3 //RAND
The negative feedback response to an increased intake of water is a(n) {~=increase~decrease} in urine volume.
//LEVEL:3 //RAND The negative feedback response to an increased intake of water is a(n) {increase~=decrease} of urine osmolarity.
//LEVEL:3 //RAND The negative feedback response to an increased intake of water is a(n) {~=increase~decrease} of plasma osmolarity.
//LEVEL:3 //RAND When you drink water the plasma osmolarity {~=decreases~increases}. This has the effect of {increasing~=decreasing} the release ADH. This in turn {increases~=decreases} the production of water channels by the nephron causing {increased~=decreased} water reabsorption. Urine osmolarity will {increase~=decrease} while volume will {~=increase~decrease}. This will {decreasing~=increasing} plasma osmolarity {~=returning to normal~separating from normal}.