Renal 8 Regulation of osmolality Flashcards
(35 cards)
changes in extracellular fluid osmolality cause changes in intracellular fluid osmolality and cell volume
renal 8 regulation of osmolality
Extracellular fluid volume is regulated by controlling water excretion and intake. Kindyes respond to hyperosmolar state as if it were a water deficit and to hypoosmolar conditions as if it were water excess
renal 8 regulation of osmolality
correction requires a positive water balance leading to increased thirst and decreased renal water excretion
renal 8 regulation of osmolality
correction requires a negative water balance leading to decreased thirst and increased renal excretion
renal 8 regulation of osmolality
rapid- occur within minutes
renal 8 regulation of osmolality
intake = output
renal 8 regulation of osmolality
1.) Loop of henle and vasarecta 2.) variable permeability of the collecting ducts to water 3.) Osmosreceptors 4.) ADH
renal 8 regulation of osmolality
Loop of henle (active exchange) NaK-ATPase drives the Na-K-2CL pum p. Creastes and osmotic gradient of 200 mOsm at each horizontal level. Creates a steep longitudinal greadient (300 mOsm in the cortex to 1200 mosm in the deep medulla)
renal 8 regulation of osmolality
Vasa recta (passive exchange) Extensions of the peritubular capillaries. Supply oxugen and nurtients to the medullary region with sluggish flow. Inflow: NaCl enters/H2O leaves Outflow: NaCl leaves/H2O enters Net effect = removal of reabsorbed NaCl and water. Fluid leaving the vasa reacta have a higher osmolarity compared to the fluid that entered (leaves more conentrated= taking away more salt back into systemic circulation)
renal 8 regulation of osmolality
the loop of henle combimed with the vasa recta
renal 8 regulation of osmolality
ADH. ADH stimulates adenylate cyclase and causes water channels (aquaporins AQP-2) to fuse in the luminal membrane
renal 8 regulation of osmolality
hypothalamus (supraoptic and paraventricular nuclei) sense the osmolality of the plasma (remember these regions do not have a BBB because they have to be able to sense the osmolarity of the plasma and change ADH release from the posterior pituitary)
renal 8 regulation of osmolality
1.) Increase the permeability of collecting duct to water 2.) Increase activity of the Na-K-2Cl pump in the thick ascending loop of henle to maintain the intermedullary gradient to ensure that we can continue to reabsorb water 3.) Increase urea reabsorption
renal 8 regulation of osmolality
Impermeable to solutes and Permeable to water (water leaves the tubule) Tubular fluid becomes increasingly more hypertonic
renal 8 regulation of osmolality
Impermeable to water and Permeable to NaCl (diffuses out) and Urea (diffuses in)
renal 8 regulation of osmolality
Impermeable to water. Na-K-2Cl transproter. Tubular fluid becomes progressively more dilute
renal 8 regulation of osmolality
hypotonic
renal 8 regulation of osmolality
the extent to which the kidneys can consevre water
renal 8 regulation of osmolality
1.) Pump: turn in NaK2Cl to move solute into the intermedullary region (until you reach 200 horizontal differnece) 2.) Water movement: allow water to go out ( flows due to solute concentration in intermedullary space) 3.) Flow: Fresh fluid (300 mOsm) flows into the loop which pushes the fluid already there around. Final result: fluid thatis leaving is hypotonic to the fluid that came in meaning we are taking away more than just salt
renal 8 regulation of osmolality
increased flow will have washout of the medullary gradient resulting in a inability to concentratre urine
renal 8 regulation of osmolality
increases the sensitivity of ADH
renal 8 regulation of osmolality
decreases the sensitivity of ADH
renal 8 regulation of osmolality
2-3% increase in osmolaity causes rapid ADH release. >10% decrease in ECBV to get same change in ADH
renal 8 regulation of osmolality
Hypothalmic osmoreceptors
renal 8 regulation of osmolality
