Water Balance

Question 1

Water Balance

Answer 1

Body increases urine when water intake is high and decreases it when water intake is low (or exercise increases, causing water loss)

Question 1

Stimulus

Answer 1

Increase in osmotic pressure - from low water volume (which concentrates solutes in blood)

Question 2

Sensor

Answer 2

Osmoreceptors in hypothalamus detect changes in osmotic pressure

Question 3

Control Center and Effector

Answer 3

High solute concentration causes water to move out of hypothalamus, making it shrink, which sends signals to pituitary to release ADH (antidiuretic hormone)

Question 4

Action

Answer 4

ADH goes to kidneys and increases water reabsorption in distal tubule (impermeable to water in absence of ADH) - conserves body water, concentrates urine, and prevents further increase in osmotic pressure

Question 5

Secondary Action

Answer 5

Shrinking of hypothalamus also causes behavioural response - thirst

Question 6

Negative Feedback

Answer 6

Fluids move from blood to hypothalamus, causing it to swell, sending message to pituitary to stop ADH production