Water Regulation

Regulating blood water potential

Stimulus
Water potential of blood increases (e.g. due to large intake of water)

Receptor
Hypothalamus stimulated

Corrective mechanism

• Less ADH released by pituitary gland into the bloodstream
• Less ADH transported to the kidneys
• Cells in the walls of the collecting ducts become less permeable to water
• Less water reabsorbed into the bloodstream
• More water excreted 
• Urine is more diluted
• More urine produced

Water potential of blood decreases

Stimulus

Water potential of blood decreases (e.g. due to loss of water through profuse sweating)

Receptor

Hypothalamus stimulated

Corrective mechanism

• More ADH released by pituitary gland into the bloodstream
• More ADH transported to the kidneys
• Cells in the walls of the collecting ducts become more permeable to water
• More water reabsorbed into the bloodstream
• Less water excreted 
• Urine is more concentrated
• Less urine produced

Water potential of blood increases