Lecture 17 Urine Concentration and Dilution Flashcards
maximum amount kidneys can excrete
20 L/day
how much does the proximal tubule absorb?
65% of filtered electrolytes
highly permeable to water
where in kidney tubule are most of filtered electrolytes reabsorbed?
proximal tubule
thin ascending loop of henle
water permeability, NaCl reabsorbed, permeability to urea, affected by ADH?
impermeable to water
reabsorbs sodium chloride
permeable to urea
no ADH effect
proximal tubule
water permeability, NaCl reabsorbed, permeability to urea, affected by ADH?
highly permeable to water
permeable to urea
no ADH
Thick ascending loop of henle
water permeability, NaCl reabsorbed, permeability to urea, affected by ADH?
impermeable to water
urea permeable
lg. amounts of NaCl, K, and other ions are actively transported from tubule into medullary intersititum
early distal tubule
water permeability, NaCl reabsorbed, permeability to urea, affected by ADH?
impermeable to water
urea permeable
lg. amounts of NaCl, K, and other ions, actively transported into intersititum
late distal tubule and cortical collecting tubule
osmolarity depends on ADH, urea is not very permeable
inner medullary collecting duct osmolarity
depends on ADH and surrounding interstitium osmolarity
what is required by the kidney tubules for the formation of concentrated urine?
presence of ADH
high osmolarity of renal medullary interstitial tubule
why must you have a high osmolarity to have concentrated urine?
establishes the osmotic gradient necessary for water reabsorption to occur
What is the role of the osmoreceptor-ADH feedback mechanism?
controls extracellular fluid and Na+ osmolarity
list the steps of the osmoreceptor-ADH feedback mechanism
increase in extracellularly fluid osmolarity -> shrinking of osmoreceptor cells in anterior hypothalamus -> action potential firing -> ADH release -> increase in water permeability in detail nephron
what is the function of the osmoreceptor cells
senses change in osmolarity
sends signal to hypothalamus for increase or decrease in ADH secretion in posterior pituitary
