Renal Blood Flow/GFR

Question 1

Characteristics of cortical nephrons

Answer 1

short loops of henle

surrounded by peritubular capillaries

Question 2

chracteristics of juxtamedullary nephrons

Answer 2

long loops of henle
vasa recta, specialized peritubular capillaries
concentrates urine

Question 3

glomerular filtrate is almost identical to plasma besides the fact that it

Answer 3

is free of RBC and proteins

Question 4

are urine and glomerular filtrate similar

Answer 4

no

Question 5

what is an index of functioning renal mass

Answer 5

total GFR

Question 6

What does a fall in GFR indicate

Answer 6

disease progression (decrease in net permeability due to loss of SA)

Question 7

what is allowed to pass thorugh glomerular membrane

Answer 7

water, small solutes

Question 8

what are the three layers of the glomerular membrane

Answer 8

fenestrated capillary endothelium
glomerular BM- collagen and proteoglycan anionic charge
Podocyte epithelium with slits

Question 9

what prevents proteins from crossing glomerular membrane

Answer 9

negative charge in the BM because some can fit. also the gate between podocytes is the last resort to keep large molecules from filtering out

Question 10

when there is a loss of negative charge in the BM of glomerulus what do we call this disease state

Answer 10

minimal change disease or nephropathy

Question 11

What are the physical forces affecting glomerular filtration

Answer 11

Hydraulic conductivity(permeability) Lp
Surface Area for filtration
Capillary ultrafiltration pressure (PUF)

Question 12

what determines the ultrafiltration coefficient (Kf)

Answer 12

product of Lp and SA

Question 13

how can you calculate GFR from the 3 physical forces

Answer 13

multiply them all

LpSAPUF

Question 14

what are the driving forces for GFR, or net filtration

Answer 14

(hydrostatic pressure of GC + oncotic bowmans which is 0) - (hydrostatic in BC + colloid glomerular capillaries)

Question 15

how do glomerular and skeletal mm capillary starling forces differ

Answer 15

in skel mm equal on afferent and efferent

glomerular the colloid oncotic pressure of GC increases as enter distal tubule

Question 16

How can the Kf or ultrafiltration coefficient be altered

Answer 16

mesangial cell contraction in intersitium that decreases the SA so you can decrease GFR to retain fluid

Question 17

How is the capillary ultrafiltration pressure changed

Answer 17

you change the pressure in the GC

Question 18

what factors determine Pressure of GC

Answer 18

renal arterial BP
afferent arteriole R
efferent arteriole R

Question 19

Where are glomerular mesangial cells located

Answer 19

in the capillary loops

Question 20

what happens when mesangial cells contract

Answer 20

shorten the capillary loops, lower the Kf and so GFR lowers.

Question 21

What is the primary way to change GFR

Answer 21

the Pressure in GC

Question 22

What occurs to GFR as pressure of GC increases

Answer 22

GFR will increase until RBF decreases too much then GFR will decrease to supply blood

Question 23

What consumes more Oxygen the brain or kidneys and why?

Answer 23

kidneys because need Na reabsorption so need Na/K ATPase activity

Question 24

/how is RBF determined

Answer 24

pressure gradient between renal A and renal v divided by the vascular R

Question 25

what controls the vascular R to RBF

Answer 25

sympathetic nervous system, hormones and the autoregulation mechanisms

Question 26

What is the GFR MAP

Answer 26

80-170 mmHg

Question 27

What are of kidney receives more blood supply

Answer 27

the cortex

Question 28

What happens with sympathetic activation to renal

Answer 28

constric afferents and lesser extent efferents, decreasing RBF and GFR to divert fraction to vital organs Renin release by granular cells ANG II Na reabsorption in prox tubule, thick ascending limp and distal convoluted tubule and collecting duct

Question 29

in what scenarios will the SANS be activated to renal system

Answer 29

hypovolemia, stress, hemorrhage

Question 30

how do the arterioles not constrict too much when undergoing SANS stimulation

Answer 30

an increase in renal PGs synthesis and release that act to dilate the arterioles

Question 31

why would you not give a hypovolemic patient NSAIDs

Answer 31

renal damage because then would prevent PGs release and arterioles would constrict too much

Question 32

What hormones increase GFR

Answer 32

PGs and Endothelial derived NO

Question 33

What hormones decrease GFR

Answer 33

Norepi, epi and endothelin

Question 34

what hormone equalizes GFR and prevents a further decrease

Answer 34

ANG II

Question 35

How does the renal system compensate for marked changes in systemic BP

Answer 35

afferent and efferent arteriole constriction

Question 36

What are the 2 mechanisms for autoregulation

Answer 36

Myogenic response from strech receptors in arterioles | tubuloglomerular feedback from and increased or decreased GFR by sensing NaCl in macula densa

Question 37

what does the myogenic response prevent

Answer 37

and increase in RBF and GFR when there is high BP

Question 38

Where is the macula densa and type of cells

Answer 38

in the begining of the distal convoluted tubule and contains extraglomerular mesangial cells (lacks)

Question 39

What is the response of the macula densa sensing an increase NaCl level

Answer 39

wants to decrease GFR so secretes adenosine which causes vasoconstriction of afferent arteriole

Question 40

how does macula densa respond to sensing low NaCl

Answer 40

increase renin release to increase ANG II that increases efferent arteriole vasoconstriction thus increasing GFR aslo will dilate afferent arteriole

Question 41

When does the tubuloglomerular feedback get activated usually

Answer 41

when the difference in volume is around 20% or more

Question 42

describe what owuld happen if giving someone with renal stenosis and hypertension and ACE inhibitor

Answer 42

ANG II production would decrease and then wouldnt have as much efferent vasoconstriction so GFR then is disrupted and could lead to more damage