GMS 6401 PRACTICE TEST QUESTIONS
AND 100% VERIFIED CORRECT ANSWERS!!
what does the urine to plasma (U/P) inulin ration tell us
an index of the total amount of water reabsorbed, throughout the tubule, relative to what was
filtered
U/P = 1.0 --> no water reabsorbed
U/P = 2.0 --> 50% water reabsorbed
U/P = 100 --> 99% of filtered water reabsorbed
what is the normal U/Pin ratio value
between 50-100
what is free water in the body
solute free, pure, distilled
what is free water clearance
volume of plasma cleared of pure water per minute
*an exception to the general clearance formula
look at how water is leaving the body relative to solute
what is the free water clearance formula
V- Cosm
Cosm = normal clearance formula
positive free water clearance
-hypo-osmotic (or dilute) urine is being removed from the body
-net excess amount of pure water removed
,negative free water clearance
-hyperosmotic urine (concentrated) being removed from body
-net gain of pure water by body due to excess removal of osmotic particles
what is the fractional clearance of urea
between 0.2 and 0.6
a waste product of protein metabolism produced by liver and excreted by kidney
freely filtered, moves passively down concentration gradient
the more water that gets reabsorbed, the more urea that will be reabsorbed as well
what does it mean if both BUN and plasma creatinine increase
kidney disease
GFR has gone up
what does it mean if BUN increases but plasma creatinine does not
dehydration
this is bc water is being conserved, which means urea is being reabsorbed and excretion is low
BUN will rise, will increase BUN:plasma creatinine ratio
in what three areas of the kidney can urea be reabsorbed
-proximal convoluted tubule
-inner medullary collecting duct
-thin ascending limb of loop of henle
which is always lower, the clearance of inulin or the clearance of urea
, urea
usually have a Curea/Cin ratio of about 0.6, which means 60% of filtered urea is excreted
how do we know if a substance has been secreted into the tubule
-if Cx > than Cin
-if fractional clearance is greater than 1.0
what is the fractional clearance of PAH (para-aminohippuric acid)
5.0
its an organic acid that is foreign to the body
there is no reabsorption of PAH
why is PAH important
-through filtration and then secretion by proximal tubules, almost all PAH administered is
cleared by the kidneys
-so, the CPAH (clearance of PAH) is about equal to the renal plasma flow rate (RPF) (the
amount of plasma flowing through the kidney)
what is the formula for effective RPF
RPF=CPAH= (UPAH/PPAH) x V
underestimates RPF by about 10-20%
correct by multiplying by 0.85
why doesn't all PAH get removed from the blood through filtration and secretion
PAH does not measure flow to the medulla bc there is no secretion of PAH in this region, so any
blood that goes through the juxtamedullary glomeruli will not have its PAH secreted
PAH secretion occurs in proximal tubule
AND 100% VERIFIED CORRECT ANSWERS!!
what does the urine to plasma (U/P) inulin ration tell us
an index of the total amount of water reabsorbed, throughout the tubule, relative to what was
filtered
U/P = 1.0 --> no water reabsorbed
U/P = 2.0 --> 50% water reabsorbed
U/P = 100 --> 99% of filtered water reabsorbed
what is the normal U/Pin ratio value
between 50-100
what is free water in the body
solute free, pure, distilled
what is free water clearance
volume of plasma cleared of pure water per minute
*an exception to the general clearance formula
look at how water is leaving the body relative to solute
what is the free water clearance formula
V- Cosm
Cosm = normal clearance formula
positive free water clearance
-hypo-osmotic (or dilute) urine is being removed from the body
-net excess amount of pure water removed
,negative free water clearance
-hyperosmotic urine (concentrated) being removed from body
-net gain of pure water by body due to excess removal of osmotic particles
what is the fractional clearance of urea
between 0.2 and 0.6
a waste product of protein metabolism produced by liver and excreted by kidney
freely filtered, moves passively down concentration gradient
the more water that gets reabsorbed, the more urea that will be reabsorbed as well
what does it mean if both BUN and plasma creatinine increase
kidney disease
GFR has gone up
what does it mean if BUN increases but plasma creatinine does not
dehydration
this is bc water is being conserved, which means urea is being reabsorbed and excretion is low
BUN will rise, will increase BUN:plasma creatinine ratio
in what three areas of the kidney can urea be reabsorbed
-proximal convoluted tubule
-inner medullary collecting duct
-thin ascending limb of loop of henle
which is always lower, the clearance of inulin or the clearance of urea
, urea
usually have a Curea/Cin ratio of about 0.6, which means 60% of filtered urea is excreted
how do we know if a substance has been secreted into the tubule
-if Cx > than Cin
-if fractional clearance is greater than 1.0
what is the fractional clearance of PAH (para-aminohippuric acid)
5.0
its an organic acid that is foreign to the body
there is no reabsorption of PAH
why is PAH important
-through filtration and then secretion by proximal tubules, almost all PAH administered is
cleared by the kidneys
-so, the CPAH (clearance of PAH) is about equal to the renal plasma flow rate (RPF) (the
amount of plasma flowing through the kidney)
what is the formula for effective RPF
RPF=CPAH= (UPAH/PPAH) x V
underestimates RPF by about 10-20%
correct by multiplying by 0.85
why doesn't all PAH get removed from the blood through filtration and secretion
PAH does not measure flow to the medulla bc there is no secretion of PAH in this region, so any
blood that goes through the juxtamedullary glomeruli will not have its PAH secreted
PAH secretion occurs in proximal tubule
