nephronmap (1)
DESCRIPTION
Nephron MapTRANSCRIPT
Na
Glucose
Na
Amino Acids
Na
Phosphate,
lactate, or
citrate,
Na
H
Na
H
Cl
Formate
ATP
KGlucose
AminoAcids
Phosphate,Lactate, orcitrate
HCO + H3- +
H CO32
CO + H O22
CO
+ H
O2
2
H + HCO3
-
+
carbonicanhydrase II
c.a. IV (blocked by acetazolam
ide)
H C
O3
2
ATP
Na
K
ATPK
ATPNa
K
ATPNa
K
ATP
Na
K
--
Na,Cl
+-
Late Proximal Tubule • Isosm. absorption
Early ProximalTubule •Isosm. abs.
-Cl
+
+
2 Cl
Na
K
+
-
+
25%
of N
a+ a
nd 2
0% o
f K+
rea
bsor
bed
(if n
ot b
lock
ed)
Fur
osem
ide
(loop
diu
retic
)
b
lock
s
Cl
K+
K+
Na+
K+
+
Na+
K+
-
Cl-
Thick AscendingLimb • load-depend. • H2O imp. • Dilutes
Thin Ascending Limb • H2O impermeable
Thiazide diuretics
block
-
+
Cl
Na
Early DistalTubule• load-depend.• H20 imp.• Dilutes• NaCl abs.
Late DistalTubule & Collecting Duct • α-Intercalated & Principal Cells• H2O imp. w/o ADH• H2O permeable with ADH
~ 3% of NA+ reabsorbed - Fine Tuning Site
~ 5% of NA+ reabso
rbed
α-Intercalated • Reabsorb K • H excretion Aldost. stim’d • H PO excret. • NH excret.
K+ATP
ATP
H+
H+
Principal Cell • Secrete K • Add aquaporin2
67% of N
a+ and K
+ reabsorbed
+
+
NH
+ H
+3
NH
(excreted)
+4K
-sparing diuretics(inhibit aldost. effect)
2 4
4+
-
(HP
O or )4 2-
2(or H
PO
)4 -
HCO + H3-
3-
+
H CO32
CO + H O22
c.a.
NewHCOabsorbed
85%
of r
eabs
orbe
d H
CO
(if
CO
fr
om tu
bule
) N
ew H
CO
(if
NH
ex
cret
ed)
33
2-
-+ 4
Angiotensin II Stimulated
Aldosterone Stimulated
ADH (vasopressin) Stimulated
ANP Stimulated
Sympathetic (Norepi.) Stimulated
Aldosterone increases # of:1. Na channels2. Na -K -ATPase pumps3. K channels+
+ +
+
ADH R
Gs
ACATP
cAMP
PKA
phosphoryl’n
H O2
H O2
Blood Flow
Na
Norepinephrine
(Sympathetic)
Angiotensin
II
ANP
P
rost
agla
ndin
& D
opam
ine
Ren
in s
ecre
t.
JGA
AN
P also blocks
blood
Afferent Arteriole
Effe
rent
Art
erio
le
Nephron Schematic
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Major effectMinor effect • insignificant, unless lots o’ stim.
Vasodilator
Vasoconstrictor