Physiology Review I

Question 1

kidney autoregulation

Answer 1

myogenic and tubuloglomerular feedback

Question 2

factors determining net filtration pressure

Answer 2

starling forces

Question 3

nephrogenic diabetes insipidus

Answer 3

ADH receptors not functioning
-cannot increase reabsorption at CD

pt loses free water - develops hypernatremia

Question 4

freely filtered material

Answer 4

Na, Cl, K, HCO3, urea, creatinine, AAs, inulin, PAH, insulin, myoglobin

Question 5

not filtered at glomerulus

Answer 5

albumin and other plasma proteins, lipid soluble substances

Question 6

filtration fraction

Answer 6

fraction of material entering kidney that is filtered - normally 20%

FF = GFR/RPF

RPF - renal plasma flow

Question 7

sympathetics

Answer 7

vasoconstriction
-greater affect on afferent arteriole

increases filtration fraction

Question 8

ANG II

Answer 8

vasoconstrictor on arterioles
efferent > afferent

preserve GFR in volume depleted state

Question 9

NSAIDs in bleeding patient

Answer 9

inhibit prostaglandins - no vasodilation

-vasoconstriction to kidney - renal failure

Question 10

Na/K ATPase

Answer 10

pumps 3 sodium out of tubule cell
pumps 2 potasisum into tubule cell

low sodium in cell - driving force - drive secondary transport of other substances

Question 11

filtered load

Answer 11

rate at which substance enters nephron

= GFR x [P]

P free (unbound) concentration in plasma

Question 12

excretion

Answer 12

= [U] x V

urine concentration x urine flow rate

Question 13

net transport

Answer 13

= filtered load - excretion rate

= (GFR x [P]) - ([U] x V)

Question 14

clearance

Answer 14

= excretion rate / plasma concentration

Question 15

glucose reabsorption

Answer 15

saturable process

Question 16

splay

Answer 16

rounding of reabsorption curve

-because some nephrons reach TM before others

Question 17

PAH

Answer 17

saturable - transport maximum system
20% filtered ALWAYS (regardless of concentration)
-always clear the GFR filtered

as concentration increases - clearance decreases

Question 18

excretion rate

Answer 18

= filtered load + secretion rate

Question 19

inulin

Answer 19

filtered only

Question 20

potassium, sodium, urea

Answer 20

filtered and SOME reabsorbed

Question 21

glucose and bicarb

Answer 21

filtered and ALL reabsorbed

Question 22

PAH

Answer 22

filtered and ALL secreted (at low concentrations)

low plasma concentration, clearance = renal plasma flow

Question 23

creatinine

Answer 23

filtered and SOME secreted

Question 24

inulin

Answer 24

gold standard for estimating GFR
-clearance independent of plasma concentration

intersection y-axis on clearance vs. plasma concentration
-GFR

Question 25

creatinine

Answer 25

freely filtered and not reabsorbed (only small amount secreted)

creatinine production = creatinine excretion = filtered load of creatinine = Pcr x GFR

-clearance always greater than inulin (some always secreted)

Question 26

glucose

Answer 26

low concentration - clearance = zero (all reabsorbed)

higher concentration - clearance reaches insulin
-never reaches it though, some always reabsorbed

Question 27

highest to lowest clearance

Answer 27

PAH > creatinine > inulin > urea > sodium > glucose = albumin

Question 28

it its in the renal vein

Answer 28

not cleared

Question 29

free water clearance

Answer 29

how much water is being excreted

positive - hypotonic urine
negative - hypertonic urine

isotonic urine = urine osmolality of 300 mOsm/kg

Question 30

C-H2O

Answer 30

= V - (Uosm x V) / Posm

urine osmolarity
plasma osmolatiry
V = urine flow rate

Question 31

sodium

Answer 31

positive clearance

almost entire filtered load is reabsorbed
-clearance just above zero

aldosterone - increases sodium reabsorption - decreases its clearance

Question 32

urea

Answer 32

freely filtered but partially reabsorbed
-floolws water

diuresis - increases urea clearance
antidiuresis - decreases urea clearance

Question 33

ADH

Answer 33

increases reabsorption of urea in medullary CD

-increased BUN, decrease in clearance

Question 34

small volume of concentrated urine

Answer 34

concentration of urea is high - but excretion not as high as in a diuresis (with much lower concentration)