一歩一歩学ぶ生命科学
POINT!

Prior to vasopressin (ADH) decreasing (at baseline), we will make the assumption that the subject is in homeostasis with normal plasma and urine osmolarities (isotonic) and urine volume.

Step 1: Suppose that the synthesis, secretion, and blood concentration of vasopressin (ADH) decreases.
Step 2: The water channel-increasing effect of vasopressin (ADH) becomes weaker, which decreases the number of water channels. This decreases the water reabsorption from the tubule.

Step 3:With the decrease in water reabsorption, concentrated (hypertonic) solution enters the plasma. This increases plasma osmolarity (concentrated, hypertonic). Because concentrated (hypertonic) solution leaves the tubule due to reabsorption, 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 diluted and increases in volume.

Challenge Quiz

1. With a decrease in the synthesis, secretion, and blood concentration of vasopressin (anti-diuretic hormone, ADH), the number of water channels in the tubule increases decreases .
2. With a decrease in the synthesis, secretion, and blood concentration of vasopressin (anti-diuretic hormone, ADH), water reabsorption from the tubule increases decreases .
3. With a decrease in the synthesis, secretion, and blood concentration of vasopressin (anti-diuretic hormone, ADH), urine volume increases decreases .
4. With a decrease in the synthesis, secretion, and blood concentration of vasopressin (anti-diuretic hormone, ADH), urine osmolarity increases decreases .
5. With a decrease in the synthesis, secretion, and blood concentration of vasopressin (anti-diuretic hormone, ADH), plasma osmolarity increases decreases .
6. The effect of decrease in vasopressin (anti-diuretic hormone, ADH) is uterine smooth muscle relaxation an increase in plasma osmolarity .
7. The effect of decrease in vasopressin (anti-diuretic hormone, ADH) is an increase a decrease the plasma osmolarity .