2024
Introduction: Renal Structure
and Function
Emily Nobles, DNP, RN, CCRN, CNE
NURS 312 Pathophysiology
University of South Carolina Aiken
-
Function of the Urinary System
substances
hormones
finia
-
?
Kidneys – excretory and endocrine function
• regulate water, electrolytes and acid-base balance
• excrete foreign chemicals and metabolic waste
materials
• synthesis and activation of renin, erythropoietin,
vitamin D and prostaglandins
Temotology
disorders
• Gluconeogenesis
(production
Ureters, Bladder, Urethra
of
• Storage and transport of urine
-
- -
I
O
.
>
-
-
-
(
RAAS
(maintains
RBC)
1
2024
>
I
Erythropoietin
-
-
that
hormone
Stimulates
Stem
cells
1m
bore marrow
↑ RBC
to
Production
Nephron
• Functional unit of the kidney
• Approx. 1.2 million/kidney (x2
• Don’t regenerate, number
declines with age
(10%/decade beginning at 40
yrs)
• Parts:
-
L4
large Renal
-
Kidneys
eletal
Glomerulus citration)
Bowman’s capsule
Proximal convoluted tubule
Loop of Henle (ascending,
descending)
– Distal convoluted tubule
– Collecting tubule
–
–
–
–
textbook
Kicheys)
=
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&
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Supplemental
folder
↑
waste
and out
got
reserve
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Filter blood
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Toxins, waste
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nee
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Kidneys/Rephone,
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Kidne
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2024
Nephron - Function
• Filtration of water-soluble substances from
blood
• Reabsorption of filtered nutrients, water and
electrolytes
• Secretion of wastes or excess substances into
the filtrate
• Different segments specialize to accomplish
these tasks.
·
Glomerulus
as
of
filtration
↳
blood
where
it
Glomerular
>
filtrate
i lo
starts
similar
-
N
To
blood
Plasma
encastel
Glomerulus
&
3
Audio
2024
(lip 4
④
moveisata
substances
↑
④
Hos)
rzsof Karen
space < perfra Glomerulus Layers
D
&
layer
② single
enothelial
,
1. Capillary
①
endothelium
①
revent 2. Basement selective
plasma membrane barter
proties /
WBC , 3. Outer capillary
RB
,Cp
[endothelium
plateless
podocytes
inner
Do
( (
gransing
↑
= °
through
(
& foot processes
-
(surrund glomerous
④ spaces blu
called silt
7
poles
makeermciable
>
-
blood
Oseperates
capillaries
W)
④
-
,
from
filtrate
from
bowmans
in
e
of Protec is
Slomeular/ss
>
-
capsule
Secretion/Reabsorption
·
tubular
reapsorbtion
↳ removal
filtrate
w/in the
of
materials
been
thathas
from
the
a
develop
s
·
tubular
↳
secretion
fluids
a re
after
:
substances
added
it
has
to
specialized
that
filtrate
extracted
been
from glomerulus
has
the
;
each
section
function
4
2024
and e
page
847
Parts of the Nephron and Function
- -
-
-
L
-
- -
-
-
-
-
-
Glomerular Filtration
i
• Movement of fluids and solutes from blood in the
Ira
secof
on
·
S
glomerulus into Bowman’s capsule
• Water and small solutes move through the
glomerulus
• Larger molecules, proteins and blood cells, unable to
Injured
move through unless glomerulas
urin)
• Resulting fluid -> glomerular filtrate (precurser
• 125 ml of glomerular filtrate produced per minute =
glomerular filtration rate (GFR)
• 20-25% of normal cardiac output (1000ml – 1300
ml/min) of blood perfuses the kidney  promotes
glomerular filtration
• Primary filtration pressures -> glomerular blood
hydrostatic pressure (2-3X higher than other capillary
beds in the body)
• Feedback mechanisms (intrarenal and extrarenal)
help to maintain blood flow and GFR
is
to
of filtration Pressures
importance
e
·
arterial Vasular
system
(
>
-
=
nepon nee
Tubularsystemof
·
G
that
for
system
Vascular
good pressure (to supply blood
and
supply blood for filtration)
·
·
blood
adequate
good
pump
adequate
(
filtration
driven
by hydrastatic
pressure
pressure
a
dra throug
blood circulate
blood
wase
fluie against
pushes
and
if
-
alt r
promote
needs
-
volume
to
to
have
Kidneys
-
Bp'fluid
room
i
Perfusion : filtration
Southe
02
(ful)
(good (a)
pressure ,
good
resistance
cul
ar
St
/enoughthe
(siltrati
promote
5
2024
audio
Clip
b
Regulation of Renal Blood Flow -GFR
a co
• Neural/Humoral Controls
Vasoconstrictor
-
– Sympathetic stimulation ↑ HR 4 BP
– Angiotensin II, ADH, prostaglandins
,
>
-
·
Stimulates
release of
aldosterme
Kidney
- -
-
• Renin angiotensin system
RASS
– Control of blood pressure
in
& Bp 4.pPirtulate e
,
-
3
• Autoregulation
hold on to
fluid
↑
circulating
blood
volume
a
·
blood supply
e
vasodilation
& Renal blood flow
↑
glomerular filtration
rate
-
– Maintain blood flow to provide a constant GFR that allows
for solute and water excretion
– Renal systems responds to arterial pressure changes and
like
sodium chlorideFrom
concentrations
• Increased protein and glucose loads
-
– Increase GFR
80-180 systolic
-
Factors Effecting Glomerular Filtration
Rate
O
• Glomerular filtration rate used to
•
•
•
•
•
•
evaluate renal tissue function
Decrease in B/P – decreases hydrostatic
pressure that drives filtration – decrease
GFR
Increased protein and glucose - increase
GFR trying to filter out 4 effecitivly
Sympathetic nervous system – decrease
GFR
Hormones – angiotensin II – efferent
↳
arteriole vasoconstriction increases
B/P increases GFR
>
Aging – loss of nephrons – decrease GFR
Prostaglandins – increase GFR
or other
damage
vasodilation
↑ Blood
flow
to
glomeras
6
2024
Relationship of GFR to Functioning Nephrons
↓ GFR
=
↓
functioning
nephrons
-
Audio
Clip 7
Indicators of Renal Function
Normal
serm-
Elevation
-
-
GFR
down
filtering as)
profeffectively
• Creatinine (0.6 –1.2 mg/dl –Adult)
– Non-protein end product of skeletal muscle
metabolism
– Eliminated to the degree renal function will
eliminate
allow How
body is able
– Most specific indicator of renal function –
estimates function capacity of the kidney
=
slowed
-
-
much
to
(Normally
I
excretion
=
or
than
(
Urinary
will
be
slightly
amount
produced
in
7
2024
Renal Function/Creatinine
↑
Creatinine
=
↓ Normal Renal
function
Indicators of Renal Function
Blood
urea
Nitrogen level
·
• BUN (8-20 mg/dL – Adult)
–⑤
Urea – byproduct of protein metabolism,
accumulates as renal function declines
– Eliminated entirely by the kidney
– Can be elevated by causes other than renal
disease (high protein diet, GI bleeding)
- m
C
Notadequatrenal
function
it CAN
by
alone
be
other
bc.
elevated
factors
-
↓
renal
function
=
4 BUN
(Not abletoend
8
2024
*
32-1
table
Pg
.
Urinalysis
na
857
• Urinalysis – gross and microscopic exam of
urine to evaluate ph, specific gravity and
presence of abnormal substances and formed
elements
• Gross exam – color, clarity, odor, sediment
• Microscopic – RBC, WBC, epithelial cells, casts,
crystals, bacteria, pH
• Specific gravity – concentration of solutes,
hydration status, functional ability of kidney
(1.010-1.025) ↓ Renal function ↓ Concentrating ability specific
Gravity
• Urine protein
- -
(
-
-
-
-
:
=
Normal
-
>
-
-
Color
·
negative for
glucose
n
·
yellow-amber
·
·blood
o
·
4 5-8
.
(around
16:
5-6)
45
⑳
.
.
·
-volu me
to
bilirubin
bacteria
·
PH
glomerulus
Probl
em/damage
With
Ei-cinalist
Ketones
-
Clarity
clear-slightly hazy
Cass
WB C-Commun
idicator
of
UT I
Crystal
·
200-2500m)/day
·
·
RBL
The “Urias”
Polyuria – increased volume of urine voided (diabetes diuretics)
failure -acute/chronic
Oliguria –↓urine output less than 400ml/day (dehydrate
Anuria – urine output less than 50ml/day
(completeObstruction
Nocturia – excessive urination at night
Hematuria – red blood cells in the urine (either microscopic/ gross)
Proteinuria – abnormal amounts of protein in
the urine
• Dysuria – painful or difficult voiding
•
•
•
•
•
•
,
-
,
~
-
absence
renal
,
Chronic Renal
faliure)
-
- -
-
m
-
9
2024
Other Terms
• Frequency – frequent voiding, more than
every three hours
• Urgency – strong desire to void (emergency got
• Hesitancy – delay, difficulty in initiating
voiding
• Enuresis – involuntary voiding during sleep
-
x
-
to
go
:
got
to
go)
,
-
-
-
-
-
Questions
• What is the functional unit of the kidney
called? nephron
• What structure in the nephron filters blood? glomerulus
• What percent of cardiac output do the kidneys
(21000-1300 mL/min)
receive under normal circumstances?
60)
• What is a normal GFR? 125 mL/min (A
(increase)
• What forces drive glomerular filtration? Bp
• What happens to urine output with
&CO
4HR
sympathetic nervous stimulation? Why? ↑
• What lab test is the most specific indicator of
renal function? Creative
20-25 % of CO
~
(lecrease)
&
↓
Stimulation , agirg
Bp , SN)
c
,
loss
of
nephrone
is it
<or >
,
4 Protein 4 Glucose , RAAS
,
bC
-
,
10
2024
Questions
(acid
•
•
•
•
:
In response to acidosis the kidneys will? Produce :
Ha0 >↑ Circulating
What is the action of aldosterone? Retain
What action to natriuretic peptides have in the kidney? Promote
Is it normal to find RBC and large amounts of protein in
the urine? NO
• What substance produced by the kidney will promote
RBC production in the bone marrow? erythropoietin
• What co-factor, synthesized by the kidney, is needed to
promote the absorption of calcium in the GI tract? Vitamin D
Conserve bicarb
Na- Retain
excrete
buffer system)
hydrogen acid
BP
-
blood
base
volume
Na
excretion
>
-
HpO
excretion
>
-
↓ circulating
blood
volume
and
-
↑ urine output
·
(cangetun)
or
procee
Kidneys
11