Unit 5 Lecture 34 Urine Flashcards
What is the goal to form dilute urine?
remove excess fluid from blood by producing dilute urine
What is one way to produce dilute urine?
drinking more water
Why does drinking more water dilute urine?
it decreases blood osmolarity which inhibits ADH release
What is the function of ADH?
Inserts aquaporins in the apical membrane that allows for water to be removed from filtrate into blood
How does filtrate osmolarity change in the nephron to form dilute urine?
descending limb - increases
ascending limb - decreases
collecting duct - decreases
What does a low filtrate osmolarity mean?
= low filtrate (nutrient/protein) concentration in liquid BC IT’S DILUTE in water!!!!!!!!
How is the late DCT and CD permeable to water?
increased ADH levels
Yes or no: is there ADH present with dilute urine?
NO! bc ADH would allow water to be reabsorbed by the blood thus making more concentrated urine
Why is the descending limb permeable to water?
HIGHER osmolarity (concentration) of interstitial fluid outside the descending limb causing water to move out of tubule by osmosis
When water leaves the descending limb, what happens to the filtrate osmolarity in the descending limb?
increases
Why does the filtrate osmolarity continue to decrease in the ascending limb?
even though it’s impermeable to water, symporters remove Na+ and Cl- so osmolarity drops
What is the goal of concentrated urine?
prevent water loss in urine by excreting only concentrated urine
What is one way to get concentrated urine?
don’t drink water
What does low water intake do to blood osmolarity and ADH?
- increases blood osmolarity (bc less water is reabsorbed into blood making blood concentration stronger)
- ADH is released
Water reabsorption in the late DCT and CD is what type of reabsorption?
facultative reabsorption
