SHolroydAtWeilCornellMedQatar/Urology/Kidney/Tubules/WaterChannels/ControlToWaterIntake
| With water intake, the plasma osmolarity decreases, and negative feedback decreases the number of water channels. |
Before water intake (at baseline), we will make the assumption that the subject is in homeostasis with adequate strength of the plasma osmolarity-decreasing effect of water reabsorption (through the water channels) as well as normal plasma and urine osmolarities (isotonic) and urine volume.
Step 1: With water intake, water leaves the plasma and osmolarity increases (concentrated, hypertonic).
Step 2: This is in the same direction as the plasma osmolarity-decreasing effect of the water reabsorption. Thus, although the strength of the plasma osmolarity-decreasing effect of water reabsorption (through the water channels) was adequate before water intake (at baseline), this strength is now too strong (red) to reverse the decreased plasma osmolarity (diluted, hyportonic) produced by water intake. Control by negative feedback is needed.
Step 3: With the strength of the plasma osmolarity-decreasing effect (through the water channels) of the water reabsorption before water intake (at baseline) being too strong (red), the negative feedback decreases (blue) the water reabsorption from the tubule.This decreases the water reabsorption from the tubule.
Step 4: With the decrease in water reabsorption, concentrated (hypertonic) solution enters the plasma. This will lead to a reverse in the decreased plasma osmolarity (diluted, hypotonic) produced by water intake, increasing it towards normal (baseline, isotonic) osmolarity. Because concentrated (hypertonic) solution leaves the tubule due to reabsorption from the tubule, the fluid remaining in the tubule has decreased osmolarity (diluted, hypotonic). Also, with the decrease in water reabsorption, there is more water remaining in the tubule. Overall, the urine becomes dulited and increases in volume.
Challenge Quiz
With water intake, the plasma osmolarity decreases, and negative feedback increases decreases the number of water channels.
With water intake, the plasma osmolarity increases decreases . This is in the same direction as opposite direction to the plasma osmolarity-increasing osmolarity-decreasing effect of the water reabsorption from the tubule (through the water channels). The negative feedback increases decreases the water channels. This will increase decrease plasma osmolarity (towards isotonic).
With water intake, water enters leaves the plasma and osmolarity increases decreases . This is in the same direction as opposite direction to the plasma osmolarity-decreasing effect of the water reabsorption (through the water channels). Thus, although the strength of the plasma osmolarity-decreasing effect of water reabsorption (through the water channels) was too strong adequate too weak before water intake (at baseline), this strength is now too strong adequate too weak to reverse the increased decreased plasma osmolarity produced by water intake. The negative feedback increases decreases the number of water channels. With the increases decrease in water reabsorption from the tubule, concentrated diluted solution enters the plasma. This will lead to a reverse in the increased decreased plasma osmolarity from water intake, increasing decreasing it towards separate from normal osmolarity. Because concentrated diluted solution leaves the tubule due to reabsorption, the fluid remaining in the tubule has an increased a decreased osmolarity. Also, with the increase decrease in water reabsorption, there is more less water remaining in the tubule. Overall, the urine becomes concentrated diluted and increases decreases in volume.