SHolroydAtWeilCornellMedQatar/Endocrinology/VasopressinADH/ControlToSweating
| Following sweating, the plasma osmolarity increases, and negative feedback decreases (synthesis, secretion, and blood concentration of) ADH. |
video prior to sweating
Prior to sweating (at baseline), we assume the subject is in homeostasis with normal plasma and urine osmolarities (isotonic) and volumes.
video just after sweating
Step 1: With sweating, water leaves the plasma and osmolarity increases (becomes hypertonic).
Step 2: ADH, water channels, and reabsorption of water by the kidney decrease plasma osmolarity, having the opposite effect of sweating. Thus, with high plasma osmolarity following sweating (hypertonic plasma), the baseline strength of the plasma osmolarity-decreasing effect of ADH, water channels, and reabsorption would be too little. Control by negative feedback is needed.
video just after the increase in ADH caused by sweating
Step 3: With the baseline strength of the ADH, water channels, and reabsorption effect being too little, the negative feedback increases (synthesis, secretion, and blood concentration of) ADH.
Step 4: The water channel-increasing effect of ADH increases, thereby increasing the number of water channels. This increases the reabsorption of water by the kidney.
video showing the changes in plasma and urine after the increase in ADH caused by sweating
Step 5: The ratio of Na+ to water entering the plasma because of reabsorption decreases. This decreases plasma osmolarity. Briefly, the increased plasma osmolarity from sweating (hypertonic plasma) decreases and returns towards normal (baseline) osmolarity (isotonic). Because a lower ratio of Na+ to water leaves the tubule because of reabsorption, the fluid remaining has a higher osmolarity (hypertonic). Also, with an increase in water reabsorption, there is less water. Overall, the urine becomes more concentrated (hypertonic) and lower in volume.
Challenge Quiz
Following sweating, negative feedback increases decreases (synthesis, secretion, and blood concentration of) ADH.
Following sweating, negative feedback increases decreases water channels in the kidney.
Following sweating, negative feedback increases decreases water reabsorption by the kidney.
Following sweating, negative feedback increases decreases urine volume.
Following sweating, negative feedback increases decreases urine osmolarity.
Following sweating, negative feedback increases decreases plasma osmolarity.
Following sweating, the plasma osmolarity decreases increases . The effect would be the same as opposite to that of ADH, water channels and reabsorption of water by the kidney, which decreases increases plasma osmolarity. The effect of (synthesis, secretion, and blood concentration of) ADH would be too little too much prior to control by negative feedback. Negative feedback increases decreases (synthesis, secretion, and blood concentration of) ADH. This in turn increases decreases the number of water channels in the kidney causing increased decreased water reabsorption. Urine osmolarity increases decreases while volume increases decreases . This decreases increases plasma osmolarity, returning to normal separating from normal .