Controlling blood water potential Flashcards
The kidney regulates the ———–of —————
Kidney regulates water potential of blood
Why is water essential
To keep body functioning therefore amount of water(water potential)needs to be constant
what’s Osmoregulation
Mammals excrete urea (and other waste products) in solution, which means water is lost during excretion.
Water is also lost in sweat. The kidneys regulate the water potential of the blood (and urine),
so the body has just the right amount of water
What happens when water potential of the blood is too low
If the water potential of the blood is too low(dehydrated) more water is reabsorbed by osmosis into the blood from the tubules of the nephrons.
What happens to urine when water potential in the blood is to low
urine is more concentrated, so less water is lost during excretion.
What happens if water potential in the blood is to high
If the water potential of the blood is too high( hydrated) less water is
reabsorbed by osmosis into the blood from the tubules of the nephrons.
What happens to urine when water potential is to high
urine is more dilute, so more water is lost during excretion
Where does the regulation of water potential take place
regulation potential mainly takes place in the loop of Henle, DCT and collecting duct
The volume of
by the DCT and collecting duct is controlled by ————-
hormones
The loop of Henle maintains a ———– —– ——–
The Loop of Henle Maintains a Sodium Ion Gradient
where is the loop of Henle located
The loop of Henle is located in the medulla (inner layer) of the kidneys
What is the loop of Helen made up of
two limbs
the descending limb and the ascending limb.
What do the limbs do
The limbs control
the movement of sodium ions so that water can be reabsorbed by the blood.
Describe how the loop of Helen maintains a sodium gradient
- At the top of the ascending limb, Na+ ions are actively transported into the medulla
- The water potential of the medulla is lowered
- Water moves out of the descending limb, into the medulla by osmosis
- The glomerular filtrate is more concentrated
- At the bottom of the ascending limb, Na+ ions diffuse into the medulla
- The water potential in the medulla is lowered
How is the volume of water reabsorbed into the capillaries
By changing the permeability of the DCT and the collecting duct
Water reabsorption is controlled by ————
Hormones
what is water potential monitored by and location
cells called osmoreceptors in a part of the brain called the hypothalamus.
What happens when water potential in the blood decreases
- Osmoreceptors in the hypothalamus detect the decrease in water potential
- Posterior pituitary gland releases ADH
- ADH binds to receptors on cell membranes of DCT and collecting duct cells
- Aquaporins move to and fuse with cell membrane
- More water can pass out and into the medulla so more water is reabsorbed
——— ——- levels rises when your dehydrated
Blood ADH
Describe how water content in the blood needs to be increased
1) The water content of the blood drops, so its water potential drops.
2) This is detected by osmoreceptors in the hypothalamus.
3) The posterior pituitary gland is stimulated to release more ADH into the blood.
4) More ADH means that the DCT and collecting duct become more permeable,
so more water is reabsorbed into the blood by osmosis.
5) A small amount of highly concentrated urine is produced and less water is lost.
Describe the process of water content being reduced
1)The water content of the blood rises, so its water potential rises.
2) This is detected by the osmoreceptors in the hypothalamus.
3) The posterior pituitary gland releases less ADH into the blood.
4) Less ADH means that the DCT and collecting duct become less permeable,
so less water is reabsorbed into the blood by osmosis.
5) A large amount of dilute urine is produced and more water is lost.
