Lecture 49+50

Question 1

what is the renal clearance equation?

Answer 1

Clearance = urine concentration x flow / plasma concentration

Question 2

how to use clearance to measure GFR (equation)

Answer 2

GFR = urine concentration x flow / filtrate concentration

Question 3

how to calculate creatinine clearance

Answer 3

Urine concentration X flow / plasma concentration

Question 4

plasma concentration and GFR graph

Answer 4

GFR and creatinine concentration are inversely related

low creatinine = high GFR
high creatinine = low GFR

BUT
the rate of excretion does NOT change

Question 5

measuring clearance of PAH

Answer 5

Renal plasma flow = concentration of PAH x flow / plasma concentration of PAH

Question 6

fractional excretion?

Answer 6

FE = urine concentration x Flow / GFR x P

Question 7

filtration fraction?

Answer 7

GFR / RPF

Question 8

Henderson-Hasselbalch Equation

Answer 8

pH = pKa + log (A- / HA)

Question 9

Acidic drugs vs basic drugs

Answer 9

Acidic:
present in the stomach uncharged
negative charge in urine
better excreted in alkaline urine

basic:
better absorbed in the intestine (uncharged)
charged in the stomach
better excreted in acidic urine (charged)

Question 10

what is the acid/base ratio for the bicarbonate buffer system

Answer 10

20:1

normal HCO3 = 24
normal CO2 = 40

Question 11

increased PCO2 and increased H+ does what?

Answer 11

hyperventilation