SHolroydAtWeilCornellMedQatar/Urology/Kidney/Tubules/WaterReabsorption/ControlToWaterIntake
| With water intake, the plasma osmolarity increases, and negative feedback decreases the water reabsorption. 飲水により血漿浸透圧が低下すると、負のフィードバックは、尿細管からの水分再吸収を減少させる。 |
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 as well as normal plasma and urine osmolarities (isotonic) and urine volume. 飲水前（ベースライン）では恒常性が保たれていて、水分再吸収の血漿浸透圧低下作用は適度な強さであり、血漿浸透圧と尿浸透圧は正常（等張）、尿量も正常であるとしましょう。
Step 1: With water intake, water leaves the plasma and osmolarity decreases (diluted, hypotonic).
Step 2: This is in 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 was adequate before sweating (at baseline), this strength is now too strong (red) to reverse the decreased plasma osmolarity (diluted, hypotonic) produced by water intake. Control by negative feedback is needed.
図の①：飲水により水分が血漿へ入るため、血漿浸透圧が低下し（薄く、低張になり）ます。
図の②：これは、水分再吸収の血漿浸透圧低下作用と同じ方向です。そのため、水分再吸収の血漿浸透圧低下作用の強さは、飲水前（ベースライン）では適度でしたが、飲水により低下した（薄く、低張になった）血漿浸透圧を戻すためにはその強さでは過剰（赤）となります。負のフィードバックによる調節が必要です。
Step 3: With the strength of the plasma osmolarity-decreasing effect of the water reabsorption before water intake (at baseline) being too strong (red), the negative feedback decreases (blue) the water reabsorption. 図の③：水分再吸収の血漿浸透圧低下作用が飲水前（ベースライン）の強さでは過剰（赤）なので、負のフィードバックが水分再吸収を減少（青）させます。
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, hyportonic) produced by water intake, increasing it towards normal (baseline, isotonic) osmolarity. Because diluted (hypotonic) solution leaves the tubule due to reabsorption, the fluid remaining in the tubule has increased osmolarity (diluted, hypotonic). Also, with the decrease in water reabsorption, there is more water remaining in the tubule. Overall, the urine becomes diluted and increases in volume. 図の④：水分再吸収が減少し、濃い溶液（高張液）が血漿に入ります。飲水により低下した（薄く、低張になった）血漿浸透圧は、飲水前の正常な（ベースラインの）浸透圧（等張）へ向けて上昇します。
再吸収で濃い溶液（高張液）が尿細管から出るため、残る液の浸透圧は低下し（薄く、低張になり）ます。水分再吸収も減少するため、尿細管に残る水分は増加します。つまり尿は薄く、多量になります。
Challenge Quiz
With water intake, the plasma osmolarity deceases, and negative feedback increases decreases the water reabsorption from the tubule. 飲水により血漿浸透圧が低下すると、負のフィードバックは、尿細管からの水分再吸収を 増加 減少 させる。
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. The negative feedback increases decreases the water reabsorption from the tubule. This will increase decrease plasma osmolarity (towards isotonic).飲水すると血漿浸透圧は 上昇 低下 する。これは、腎臓/尿細管からの水分再吸収の血漿浸透圧 上昇 低下 作用と 同じ 逆の 方向であり、負のフィードバックは尿細管からの水分再吸収を 増加 減少 させる。これは尿量を 増加 減少 させ、尿浸透圧を 上昇 低下 させ、血漿浸透圧を(等張へ向けて) 上昇 低下 させる。
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. Thus, although the strength of the plasma osmolarity-decreasing effect of water reabsorption 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 water reabsorption from the tubule. Thus, 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.