Exam 6- Renal System (without pathology) Flashcards
kidney regulates
- long term blood pressure
- blood cell count /hemoglobin levels (produces erythropoietin)
- Ca2+ homeostasis(activates vit. D)
kidney structure
v
functional unit of the kidney=
nephron
juxtaglom vs cortical neph
m
renal corpuscle=
glomerulus + bowman’s capsule
tubule path
Proximal tubule (convoluted and straight)
Loop of Henle
Distal convoluted tubule
Collecting duct (cortical and medullary)
after collecting duct urine passes to___
minor calyx
major calyx
renal pelvis
ureter
peritubular capilaries surround
cortical segments of tubule
vasa recta surrounds
loop of henle
blood pathways
- efferent arteriole -> peritubular cap-> renal vein
- efferent art. -> vasa recta -> renal vein
three processes involved in urine production
glomerular filtration
tubular resorption
tubular secretion
___+_____+______= amount excreted
amount filtered + amount secreted - amount reabsorbed
filtered load
= “amount filtered”
glomerular filtration barrier needs to achieve=
- high H20 filtration rates
- nonrestricted passage of small/mid sized molecules
- total restriction of serum albumin, proteins and cells
layers of filtration membrane
endothelial cell
basement membrane
pedicels of podocytes/filtration slits with diaphragm
diaphragm between podocytes=
web of nephrin
what is freely filtered trough glom. filtration membrane
water
electrolytes
glucose
amino acids
urea
NOT big protiens and cells
osmolality of plasma and filtrate
300mOsm/kg
[Na+] in plasma and filtrate
both 140mEq/L
[glucose] in plasma and filtrate
100mg/dL
[albumin] in plasma and filtrate
plasma= 4mg/dL
filtrate= NONE
forces that affect filtration
starling forces= hydrostatic pressure oncotic pressure
filtration promoting forces
- Pgc - Glomerular capillary hydrostatic pressure
- π BS- colloid osmotic or oncotic pressure in bowman’s space (but this is practically zero…)
filtration opposing forces
- Pbs- hydrostatic pressure in bowman’s space
- πGC- glomerular capillary oncotic pressure = amount of proteins in plasma
net filtration pressure=
“ultrafiltration pressure” NFP = (+)Pgc - Pbs- πGC
filtration coefficient (Kf) determined by
- hydraulic permeability of the membrane
- surface area of the filtration membrane - both mainly change with disease
glomerular filtration rate =
(equation)
= Kf x NFP = (filtration coefficient) (net filtration pressure)
what makes glomerulus different than other capillary beds
- Kf is very high- lots of fenestrations ~20% of plasma flowing through is filtered
- low resistance in glomerulus, high P in glomerulus
- losing 20% of plasma increase πGC which would oppose filtration, but the high renal blood flow limits this
GFR=____ ml/min or ____L/day
amount of filtrate/min healthy = 125ml/min or 180L/day
healthy people control ___ to ∆ GFR
Pgc
pathologies affect ____ to ∆ GFR
Pbs πGC πBS
___ affect Pgc
Mean arteriole pressure
resistance at afferent and efferent arterioles
MAP decreases = Pgc____ and GFR___
Pgc decreases GFR decreases
afferent arteriole dilates = Pgc____ and GFR___
Pgc increases GFR increases
constrict aff. arteriole = GFR ___
decreases
eff. arteriole dilates = Pgc____ and GFR___
Pgc decreases GFR decreases
constrict aff. arteriole and eff. arteriole at the same time = GFR _____
GFR stays the same
plasma protein concentration increases = πGC____ GFR___
πGC increases GFR decreases
filtration membrane becomes more permeable = πBS____ GFR___
πBS increases GFR increases
kidney stone blocks a ureter = Pbs____ GFR____
Pubs increases GFR decreases
blood flow rates in
kidney cortex=
outer medulla=
inner medulla=
cortex= 4-5
outer medulla= 0.7-1
inner medulla=0.2-0.25
When mean arteriole blood pressure is between ____ the kidney can auto regulate it.
80 to 140mmHg
below range, then GFR is too low
above range, then glomerulus is damaged
two components of auto regulation
- myogenic response
- tubuloglomerular feedback
myogenic response
MAP increases (causes and increased RBF, Pgc, and GFR)
=stretches the afferent arteriole
=afferent arteriole then constricts which then decreases RBF, Pgc, and GFR
tubuloglomerular feedback
increased MAP
=transient increase in GFR
=increase NaCl delivery to macula densa
=release adenosine
=constricts afferent arteriole
small drop in MAP is dealt with by=
myogenic response and tubuloglomerular feedback =dilation of afferent arteriole
HUGE drop in MAP is dealt with by=
myogenic response and tubuloglomerular feedback
=dilates afferent arteriole BUT we’re out of auto regulation range… so our GFR and RBF and Pgc drop… yikes…
autonomic NS responds to HUGE drop in MAP by___
activating SNS = constricts afferent arteriole yikes!!
end results with HUGE decrease in MAP
decrease in perfusion pressure Pgc and GFR
+ autoregulation dilates aff. art.
+ SNS hugely constricts afferent arteriole (further decreasing Pgc and GFR)
=LARGE DECREASE IN PGC AND GFR
why does SNS constrict the aff. arteriole with huge drop in blood pressure
body’s trying to decrease renal blood flow so less blood goes to kidney so it can go to heart and brain
renal artery stenosis
decreased RBF, Pgc, GFR
auto regulatory response to renal artery stenosis
dilate the afferent arteriole AND constricts the efferent arteriole
efferent arteriole is constricted via___
RAAS
- Juxtaglomerular cells =>renin
- (+) angiotensin II which constricts eff. arteriole
NSAIDS effect
inhibits prostaglandins which normally dilate afferent arteriole
decreased effective circulating blood volume (heart failure) causes…
- (+) SNS = constrict afferent arteriole (alpha 1) and (+) B1 on JG to (+) RAAS
- (+) RAAS = constricts efferent arteriole
END RESULT= decreased RBF, but somewhat maintained GFR
large amounts of both NE and Ang II=
decreased RBF, but somewhat maintained GFR
=renal ischemia
=increased prostaglandin production
=dilate the afferent arteriole somewhat counteracts the decrease in RBF and prevents ischemia
why is it bad to take an NSAID if you have heart failure?
NSAIDS (-) prostaglandin aff. arteriole dilation which would increase GFR and RBF and therefore causes lower RBF and GFR which= ACUTE KIDNEY INJURY
Renal Clearance=
Volume of plasma cleared of a substance per unit time Volume/Time
Normal GFR=
125ml/min
A substance is filtered and reabsorbed but not secreted then its clearance is > GFR
LESS THAN
clearance = GFR then _____ reabsorption or secretion
no net
clearance > GFR then there has been net _____
secretion
clearance
reabsorption
p-aminohippurate (PAH)
-not endogenous -at low concentrations PAH is filtered, none is reabsorbed and the rest is secreted ∴ PAH is a measure of renal plasma flow