click below
click below
Normal Size Small Size show me how
Renal Phys 7
WVSOM -- Renal Phys -- Concentration and Dilution of urine
Question | Answer |
---|---|
What is countercurrent multiplication? | a process which dilutes loop fluid and at the same time concentrates the medullary interstitum. |
What is coutner current exchange? | process in the looped vasa recta tha protects the osmotic gradient in the medulla |
What are the key concepts about countercurrent multiplication? | concentrates loop fluid and reilutes the fluid. Processes a dilute urine to the distal tubule. Creates a concentrated medullary interstitium thru wich the collecting ducts run. |
What is the point of final concentration or dilution? | collecting ducts |
How does osmolality incrase or decrease horizontally across the medulary? | it doesn’t |
How does osmolatlity change from outer to inner medulla? | increasingosmolaity as you go deeper. |
Where does ADH act from? | Initial collecting tubule to inner medullary collecting duct. |
What is the osmolality of the cortical interstitium? | same as plasma |
What is the corticomedullary osmolality gradient? | becomes increasingly hyperosmotic as you descend into the medulla |
What happens when someone has been on restricted water intake? | ADH is secreted. H3O flows out of collecting tubules and urine becomes concentrated with decreased urea permeability. |
What happens to urine in the TAL with a patient on loop diuretics? | urine doesn’t get diluted |
What happens to the interstitium in a patient on a loop diuretic? | does not get concentrated. |
What happens to distal nephrons in patients on loop diuretic? | increased delivery of Na and solutes that prevent H2O reabsorption |
What happens to H2O in the descending limb in a patient on a loop diuretic? | decreased reabsoprtion |
What happens to urine in a patient on loop diuretics? | urine becomes isomotic |
What happens to a person who is a victum of water loading? | low levels of ADH, low H2O permeability in CT on down, excrete a dilute urine and a low urea permeability |
What will create an increasing osmolatity in the medulla? | NaCl and Urea |
What happens to urea concentrations as you travel thru the medulla? | urea concentration rises steeply from the middle of the outer medulla to the pailla |
What does urea concentrations rise in the medulla? | due to the unique water and urea permeabilities of the collecting tubules and ducts |
What will stimulate urea transporters in the medulla? | ADH |
Where is urea reabsorbed and how much? | half reabsorbed in the PT |
Where is urea secreted? | thick loop of loop of henle to the medullary collecting duct |
What determins medullary osmolality? | half due to urea and half due to NaCl |
Urea transport depends on _______________ differences | concentration |
What happens at low urine flows? | more water has time to be reabsorbed thus leaving lots of urea in the tubule to set upa concentration difference. More UREA is reabsorbed |
What happens to urea at high flows? | less urea is reabsorbed because more water is swept downstream and less is reabsorbed |
What happens in renal disease? | low GFR which leads to low urine flow, increase in urea retention and increased BUN |
What happens to urin with a low protein intake? | Greatly reduced metabolic production of urea and the patient will have a compromised ability to produce concentrated urine |
What happens to urine with dehydration? | GFR is low and ADH is high so more water is removed from the tubule resulting in a more concentrated medullary intstition due to ADH causing a stimulating urea reabsorption |
What happens to urine in diabetes insipidious? | patienst have polyuria and poly disia due to low ADH |
What is central Diabetes Insipidous? | failure of ADH secretion |
What is nephrogenic diabetes insipidous? | Kidneys respond inadequately to ADH |
What is SIADH? | syndrom of inappropriate ADH |
What happens to urine in SIADH? | patients re-absorbe lots of water so urine becomes a lot more concentrated and the plasma na concentration goes down (hyponatremia) |
Describe the vasa recta | low blood flow with descending and aswcending limbs that run near each other in parallel |
Describe solute and water movement in the vasa recta | can enter and leave BUT there is no capacity for active transport |
What happens to osmolaltiy in the vasa recta? | increases as it passes deeper. |
Does countercurrent exchange in the vasa recta establish a medullary osmotic gradient? | no, instead it keep the gradient created by the countercurrent multiplication from dissipating |