Renal DSA Flashcards
(26 cards)
What are the three layers of the glomerular filtration barrier?
- capillary endothelium
- glomerular basement membrane
- podocyte
*must pass these three barriers to go from the capillary lumen to Bowman’s capsule
What does the glycocalyx make? what is it made of?
- biogel (provides molecular filling to the fenestrae of the capillary)
- hyaluronan, heparan sulfate
What is the function of Tamm-Horsfall protein?
antimicrobial molecule combating UTIs
-does appear in the urine, but is not filtered
As size increases, filtration…
decreases
Filtered load of X=
plasma concentration of X x GFR
Urinary excretion
amount filtered - amount reabsorbed + amount secreted
Tubular excretion
glomerular filtration - urinary excretion + amount secreted
If excretion is greater than filtration, what must have occurred?
tubular secretion
Urine excretion rate of x=
Ux X V
- Ux: the [} of a substance in the urine in a given volume
- V: rate at which urine is produced
What is renal clearance (C)?
the volume of plasma completely cleared of a substance by the kidneys per unit of time
C=(Ux X V)/Px=mL/min
Glomerular filtrate is similar to plasma except that it is…
protein free and cell free
*represents 20% of RBF
Filtration Fraction (FF)=
GFR/RBF
As FF increases, the oncotic pressure of the ____ arteriole increases
efferent
What is the difference between filtered load and filtration fraction?
a. a rate in mg/min
b. a ratio of GFR to RBF
GFR is directly proportional to renal clearance if what four things are true?
- Substance must be freely filterable in the glomeruli
- Substance must be neither reabsorbed nor secreted by the rental tubules
- Substance must not be synthesized, broken down, or accumulated by the kidney
- Substance must be physiologically inert (not toxic)
ex. Inulin and creatinine
Three mxns by which the sympathetic nervous system increases BP
- JG cells to secrete renin (beta 1)
- Na+ increased reabsorption (alpha 1)
- Vasoconstriction (afferent»efferent; alpha 1)
What are the immediate effects of sympathetic stimulation?
a. Angiotensin II–> exert thirst, vasoconstriction, acts on efferent arteriole
b. stimulates renin secretion
c. GFR is stabilized
d. systemic BP is raised
e. Na+ reabsorption in PCT/DCT
What are the eventual effects of sympathetic stimulation?
a. decreased urinary output
b. decreased urinary Na+ excretion
c. increased water intake
How are plasma creatinine and GFR related?
inversely proportional
How would you recognize a pre-renal problem?
- BUN>20:1
- Mxn: BUN reabsorption is increased
- example: hypovolemia, dehydration, reduced renal perfusion, high protein diet
How would you recognize a post-renal problem?
- Bun levels are normal
2. Mxn: post renal disease
How would you recognize a intrarenal problem?
- BUN<10:1
- Mxn: renal disease reduces BUN reabsorption
- example: Liver disease, low protein diet
What is PAH used to measure?
- Renal blood flow
- PAH is not typically in the human body, so it must be administered by continuous intravenous infusion
*we can assume all PAH presented to the kidneys is excreted in the urine
Signals that increase GFR
NO, dopamine, prostaglandins
