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MSS - Renal Exam 1 > Elements of Renal Function > Flashcards

Flashcards in Elements of Renal Function Deck (51):
1

kidney function?

regulate ECF concentration
regulate plasma electrolyte concentration
regulate acid base balance
regulate extracellular fluid volume, arterial blood presure
eliminate metabolic waste

2

hormones in kidney?

erythropoietin
vitamin D
renin

3

synthesized in kidney?

ammonia
prostaglandins
kinins
glucose

4

kidney is important?

integrated with many other body systems

renal failure: anemia, osteoporisis, disregulation of calcium and phosphate

5

kidneys a blood pressure

also regulated

6

renal blood supply

20% cardiac output

7

renal BP?

glomerular capillaries - 60 mmHg
-pretty high

8

pressure in peritubular capillaries

lower (13 mmHg)

permits fluid reabsorption

9

pressure in capillary beds?

can be regulated by resistance changes in afferent and efferent arterioles

10

two types of nephrons?

superficial
juxtamedullary (much longer loops of henle)

11

cortical nephron?

short loop of henle
-surrounded by peritubular capillaries

12

juxtamedullary nephron

long loop of henle
-long efferent arterioles divided into specialized peritubular capillaries (vasa recta)

13

renal microcirculation?

afferent arteriole
glomerular capillaries
efferent arteriole
peritubular capillaries

14

vasa recta

runs alongside loos of henle in juxtamedullary nephron

15

venous drainage?

interlobular vein
arcuate vein
interlobar vein
renal vein

16

first capillary network?

glomerular capillaries
-high hydrostatic pressure
-large fluid volume filtered in bowmans capsule

17

second capillary network?

peritubular capillarires
-low hydrostatic pressure
-law amounts of water and solute are reabsorbed

18

renal blood flow

very high flow

19

renal flow during exercise?

decreased flow
-blood is shunted to skeletal muscle

20

flow rates in regions of kidney?

cortex highest
slower as get more central (outer to inner medulla)

slow rate in medulla allows concentration of urine

21

innervation of kidney?

sympathetics on smooth muscle on arterioles and granular cells in afferent arterioles

22

granular cells

on juxtaglomerular apparatus
-sympathetic stimulation of renin release

23

sympathetic stimulation?

powerful constriction of afferent and efferent arterioles
-afferent > efferent

decreases renal blood flow
diverts renal fraction to vital organs

also stimulates renin release

24

renin

stimulates Na+ reabsorption in proximal tubule, thick ascending loop of henle, distal convoluted duct, collecting duct

25

glomerular filtration

filtration of plasma from glomerular capillaries into bowmans capsule

26

tubular reabsorption

transferral of substances from tubular lumen to peritubular capillaries

27

tubular secretion

transferral of substances from peritubular capillaries to tubular lumen

28

excretion

voiding of substances in urine

29

urinary excretion = ?

amount filtered - reabsorbed + secreted

30

tubular reabsorption = ?

glomerular filtration - urinary excretion

if excretion rate > filtration rate, tubular secretion must have occurred

31

glomerular filtration rate

volume of plasma filtered into combined nephron of both kidneys per unit time

32

filtration rate

GFR x plasma concentration of substance

33

urinary excrection rate?

flow rate x concentration of substance in urine

34

reabsorption or secretion of substance?

difference between glomerular filtration and urinary excretion (assuming substance is not produced or metabolized by kidneys)

35

excretion < filtration

net reabsorption occured

36

excretion > filtration

net secretion occured

37

clearance

volume of plasma from which a substance is completely removed by kidney in given time period

describes how effectively the kidneys remove a substance from the bloodstream and excrete it in the urine

different substances have different clearance

GFR measure depends on clearance

38

clearance of substance = ?

concentration in urine x urine volume /
concentration of substance in plasma

Cx = Ux x V / Px ***

39

GFR estimate?

can be done using clearance

-if compound freely filtered, but NOT secreted, reabsorbed, produced, nor degraded by the kidneys

40

inulin

freely filtered, not reabsorbed, secreted, or metabolized

inulin clearance equal to GFR

problems - need to inject it

41

creatinine?

another estimate of GFR
-freely filtered, but not perfect

creatinine secretion in proximal tubule overestimates Ux; substances in blood cause overestimation of Px

two sources of error nearly cancel eachother out

42

P-creatinine and GFR?

plasma creatinine

inversely proportional

not perfect, difference in lean muscle
compensatory increased proximal tubule secretion

43

uses of creatinine?

long term function

44

BUN/creatinine

creatinine from muscle
BUN from liver (waste product)

urea reabsorbed by tubules can be regulated
creatinine reabsorbed remains the same

45

BUN/Cr >20/1

prerenal problem
-BUN reabsorption is increased
-due to hypovolemia

creatinine doesn't change with hypovolemia

46

BUN/Cr 10-20/1

normal range or postrenal
-can be postrenal disease (obstruction)

47

BUN/Cr <10/1

intrarenal
-renal damage causes reduced reabsorption of BUN and a lower BUN/Cr ratio

48

cystatin C

another marker of GFR
-produced by all nucleated cells
-freely filtered
-not dependent on muscle mass or gender

it goes up, GFR goes down

used to determine estimage GFR (eGFR)

49

para-amino hippuric acid (PAH)

freely filtered and avidly secreted
-completely cleared from plasma of peritubular capillaries

gives estimate of blood flow

50

filtration fraction

renal plasma flow through the tubule

FF = GFR/RPF

RPF = renal plasma flow

51

increased FF

oncotic pressure of efferent arteriole increases
-facilitates reabsorption