Lecture 32: Glomerular Filtration

Question 1

3 processes of nephrons and collecting ducts

Answer 1

glomerular filtration

tubular reabsorption

tubular secretion

Question 2

glomerular filtration

Answer 2

part of blood plasma filtered into kidney golmerulus is a knot

blood flows through BP pushes plasma through fluid leaving pushed through filtering system

FILTRATION ONLY HAPPENS IN GLOMERULARIS

Question 3

tubular re-absorption

Answer 3

water and useful substances reabsorbed into blood mostly water

Question 4

tubular secretion

Answer 4

wastes are removed from blood and secreted into urine

Question 5

excretion=

Answer 5

excretion= glomular filtration+secretion-re=absorption

Question 6

rate of excretion

Answer 6

rate of filtartion + rate secretion - rate reabs

Question 7

what enhances filterating capacity

Answer 7

thiness of membrane large SA of glomerular capps glomerular capp blood pressure high due to small size of efferent arteriole (exit smaller than input=more BP)

Question 8

what does blood pressure produce?

Answer 8

glomerular filtrate

Question 9

filtrate fraction

Answer 9

20% of plasma

so it may take 2 or 3 times to filter out a toxin

Question 10

how much reabs per day?

Answer 10

48 gallons/day filtrates reabs to 1-2 qt urine

Question 11

Net Filtration Pressure

Answer 11

NFP= total pressure that promotes filtration

NFP=GBHP - (CHP +BCO)

=10 mm Hg 55- (15+30)=10

if pressure higher, system wouldn’t work right

Question 12

Glomerular Filtartion Rate (GFR)

Answer 12

amount of filtrate formed in all renal corpuscles of both kidneys/min

about 125 mL/min in adults (180 L/ day)

Question 13

Homeostasis req for GFR

Answer 13

constant!

too high= loss of useful subastnaces due to speed of passage through nephron

too low= waste products may not be removed enough from body

Question 14

GFR=

Answer 14

NFP= GHBP=CHP-BCOP mean arterial pressure-? afferent AP-> CHBP-> NFP-> GFR

Question 15

what affects GFR?

Answer 15

changes in net filtration filtration stops of GBHP drops to 45 mm Hg (from 55) (45-45=0, nothing filtered out, just exits)

Question 16

GHBP determined by…

Answer 16

MAP

Question 17

kidney functions normally…

Answer 17

with MAP 80-180 mm Hg b/c of GFR reg

Question 18

GFR Regulation

Answer 18

1) Autoregulation of GFR
2) Neural Regulation of GFR
3) Hormonal Regulation of GFR

Question 19

Autoregulation of GFR

Answer 19

mechanisms that maintain constant GFR depiste arterial BP changes

myogenic mech

tubulogomerular feedback

Question 20

myogenic mechanism

Answer 20

fast

systemic inc in BP stretch afferent arteriole

smooth muscle contraction reduces diameter of affernt arteriol,

GFR returns to pervious level in secs

Question 21

tubuloglomerular feedback

Answer 21

slower

elevated systemic BP raises GFR, fluid flows to quickly through renal tubule (NA, Cl, water not reabsorbed)

macula densa in ascedning LH detects inc in NA and Cl,

inhibits relase of Nitric Oxide (vasodialer) from JG apparatus

afferent arterioles constrict, reduce GFR

Question 22

Neural Regulation of GFR

Answer 22

blood vessles of kidney: supplied with symp fibers, cause vasoconstriction of affernt arterioles

Norepu relase from symp postgang binds alpha 1

adrenergic recprot-> vasocnstrict of affernt arteiroles

Question 23

Neural Regulation of GFR

Answer 23

SNS overides renal autoreg if needed also stims renin release from JG cells

Question 24

Neural Regulation of GFR: renal blood vessles at rest

Answer 24

maximally dialated b/c symp activity minimal (autoreg working)

Question 25

Neural Regulation of GFR: moderate symp stim

Answer 25

both afferent and efferent arterioles constrict equally, dec GFR a little

Question 26

Neural Regulation of GFR: exreme symp stim

Answer 26

exercise, hemmorahage GFR dec a lot lower urine output to maintain blood vol greater blood flow to tissues

Question 27

Hormonal reg of GFR

Answer 27

atrial natruretic peptide (ANP) INCREASES GFR stretched ATRIA occurs with inc blood volume--\> hormonal release relax GLOMERULA MESANGIAL cells--\> inc glomerular capp SURFACE AREA and thus GFR

Question 28

Hormonal reg of GFR and Angiotensin II

Answer 28

REDUCE GFR partly activated by renin from JG cells potent vasoconstricter-\> narrows afferent and effernt arterioles, reduced GFR)

Question 29

endothelial fenestrations of glmerulus

Answer 29

stops all cells and platelets (formed blood cells retaied)

Question 30

basal lamina of glomerulus

Answer 30

stops large plasma proteins (they are retained)

Question 31

slit membrane between pediceles

Answer 31

stops medium sized proetins, not small ones

Question 32

NFP stands for

Answer 32

net filtration pressure total pressure that promotes filtration

Question 33

GBHP stands for and number

Answer 33

glomerular blood hydrostatic pressure 55 mm Hg

Question 34

CHP stands for and number

Answer 34

capsular hydrostatuc pressuer 15 mmHG

Question 35

BCOP stands for

Answer 35

blood colloid osmotic pressure 30 mmHG

Question 36

filtration membrane

Answer 36

1. endothelial fenestrations of glmerulus 2. basal lamina of glomerulus 3. slit membrane between pediceles all not stopped passes through

Question 37

GBHP

Answer 37

pushes things out into capsular space

Question 38

## Footnote CHP

Answer 38

retarding push out

Question 39

BCOP

Answer 39

trying to hold proteins into blood

Question 40

ex of neural symp

Answer 40

norepi relase from symp post gang neuron neurons bind to alpha 1adrenergic receptors =vasconstrict afferent arterioles