Quantitative Renal Physiology Or Evaluation Of Renal Function--Prestudy

Front 1

What is mass flow? Equation?

Back 1

Expression of solute movements as a function of time.

In solution = expressed as a product of concentration and rate of flow

Mass flow = concentration x volume flow = (amount/mL) x (ml/minute)

Front 2

What is the mass flow of Na+ equation:

What is the equation for the mass flow of creatinine?

Back 2

.078 mmol/mL x 1.5 mL/min = .117 mmol/min

(2 L/day) x (1000 mg/L) = 2000 mg/day or 83.3 mg/hour or 1.4 mg/min

Front 3

What does rate of output equal?

1.) ingestion of solute that is not produced in body (salt)?
2.) Metabolism of ingested solutes (glucose)?
3.) Solutes produced only by metabolism (urea, uric acid)?

Back 3

Rate of intake + rate of production

1. Rate of output = rate of intake
2. Rate of output = rate of intake + rate of production - metabolism
3. Rate of output = rate of production

Front 4

True of false.

Plasma concentration will be constant at a steady state.

Back 4

True

Front 5

What is the equation for mass balance in the kidney?

Back 5

Rate of input to kidney = rate of output from kidney (renal vein + lymphatics + urine)

--> Mass flow in kidney = rate of flow from four different routes x concentration in each flow

Front 6

What are the inputs/outputs of kidney?

Back 6

Input = rental artery
Output = urine, renal vein, lymphatics

Front 7

If arterial BUN (urea) is 25mg/dL and plasma flow into kidney is 690 mL/min, what is urea input into kidney?

What if urinary output is 20 mg/min? What would venous + lymphatic urea output be?

Back 7

(25mg/dL) x (6.9 dL/min) = 172.5 mg/min

172.5 - 20 = 152.5 mg/min = venous + lymphatic urea output from kidney

Front 8

Water input to the kidney is the same as plasma flow into kidney (690 mL/min). If urinary water flow is 1 mL/min, what is kidney venous + lymphatic water output?

Back 8

690 - 1 = 698 mL/min

Front 9

What is the equation for mass balance along the nephron?

Back 9

Filtration + secretion = excretion + reabsorption --> excretion = filtration - reabsorption + secretion

Front 10

What is the equation for the rate of filtration or excretion?
What does filtration rate equal? What does excretion rate equal?

Back 10

Rate of filtration or excretion = solute concentration x volume flow rate

Filtration rate = GFR x Px
Excretion rate = UF x Ux

Front 11

What is an indicator of extent and progression of renal disease?

What is the CLINICAL indicator of extent and progression of renal diseases?

Back 11

Kidney function
--> specifically GFR, plasma clearance of solutes, and renal blood flow

GFR (loss of glomeruli due to sclerosis and destruction)

Front 12

How do you measure kidney function?

Back 12

INULIN!
--> not produced in the body, not metabolized, ONLY excreted by kidney, not secreted by tubule, not reabsorbed by tubule

Front 13

What is the equation for plasma inulin?

Back 13

Pin = rate of infusion/rate of output

Front 14

What are the equations to use for measuring GFR?

Back 14

Rate of filtration = rate of excretion

GFR x Pin = UF x Uin
GFR = UF x Uin/Pin = clearance

Front 15

What is clearance?

What are the two equations?

Back 15

Volume of plasma that is completely cleared of the substance by the kidneys per unit time.

Uin = GFR x Pin/UF
Cin = (UF x Uin)/Pin

Front 16

What is the general equation clearance?
What does the clearance of inulin equal?
What is the effect or reabsorption on Cx?
What is the effect of secretion on Cx?

Back 16

Cx = (UF x Ux)/Px
GFR
Cx = Cx < Cin or GFR
Cx = Cx > Cin or GFR

Front 17

What is the extraction ratio?
What is the effect or reabsorption?
What is the effect of secretion

Back 17

Percentage of substance removed from the plasma.

Ex ratio X = (Ax-Vx)/Ax
Effect of reabsorption = low extraction ratio
Effect of secretion = high extraction ratio

Front 18

If substance X is completely cleared from plasma, what does clearance equal?

What is the clearance of PAH?

Back 18

Cx = total renal plasma flow
Cpah is approximately effective renal plasma flow (RPF) = (UF x Upah)/Ppah = 585 mL/min

Front 19

What is an endogenous indicator of GFR?
How is it made?

Back 19

Creatinine, by-product of skeletal muscle metabolism

Front 20

Review this slide.

Back 20

GFR = 1.8 g/day = 180 L per day

Pcr will double from 1 mg/dL to 2 mg/dL

Front 21

What is the relationship between plasma creatinine and GFR?

Back 21

Increase GFR, decrease plasma creatinine