Renal Function Flashcards
List the 3 things that compose the Glomerular Filtration Barrier
1) Capillary Endothelium
2) Glomerular Basement Membrane
3) Podocyte Epithelium
Molecules < ___ A are freely filtered
20
Molecules > ___ A are not filtered
42
Lammina Rara Externa is exposed to the ____
Bowmans Capsule
Lamina Rara Interna Is exposed to ___
Blood
Describe what the Lamina Rara Interna and Lamina Rara Externa are composed of and how it contributes to the charge of the GBM.
1) Proteoglycans, Predominately Heparin Sulfate
2) Have electronegative charge
How does the Glycocalyx contribute to the charge of the GBM?
Provides a negative charge
Concentrations are ___ on both sides of the GBM
Equal
How do you calculate Urinary Excretion
Amount Filtered - Amount reabsorbed + Amount Secreted
How do you calculate Tubular Reabsorption?
Glomerular Filtration - Urinary Excretion + Amount Secreted
If excretion > filtration, then ____ must have occurred
Tubular secretion
In terms of the Kidney, Arterial input must equal ____ + ____
1) Venous Output
2) Urine Output
How do you calculate urinary concentration of X (Ux)?
Ux = Concentration/Volume
Define Urinary Concentration
Concentration of that substance in the urine in a given volume
How do you calcular Urine Flow Rate?
V = Urine volume/ time
How do you calculate urine excretion rate?
Ux * V
Urinary Concentration multiplied by the Urine Flow Rate
Urine excretion rate is directly porp. to ___ and __
Urine Concentration and Urine Flow Rate
Clearance is a ____ rate
Flow
Define Renal Clearance
Volume of plasma completely cleared of a substance by the kidneys per unit time
Renal Clearance is the ratio of:::
urinary Excretion (Ux * V) to Plasma Concentration (Px)
What are the units for Renal Clearance and what does it mean?
1) Volume per unit time
2) Volume of plasma cleared of the substance per unit time
What is the Equation of Renal Clearance of a Substance
Cx = Ux * V/ Px
Define Glomular Filtrate (GF)
The fluid filtered across the glomerular capillaries into Bowns Space
____ = Volume of plasma filtered into the combined nephrons of both kidneys per unit of time (mL/min)
Glomerular Filtration Rate (GFR)
How do you calculate Capillary filtration coefficient (Kf)
Permeability * Surface Area
What is the normal Filtration Frcation?
20%
How do you calculate Filtration Fraction?
FF = GFR/RBF
What does the Filtration Fraction represent?
Fraction of RBF that is filtered across the Glomerulus and reaches the tubules
How will an increased of ultrafiltration pressue influence FF?
Increase
FF = GFR/RBF; so as Ultrafiltration pressure increases GFR will increase leading to an increase in FF.
How does an increase of RBF influence FF?
Decreases