SCIT 1408 Applied Human Anatomy and Physiology II - Urinary System Chapter 25 A

8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Urinary System Chapter 25 A

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Kidney Functions

Filters 200 liters, 120ml/min blood/day

Urea, uric acid, creatinine, excess ions (Na+, K+,

Cl-, HC!-, H+" excreted in#

2 liters/day urine $e%ulates blood &olume, blood c'emicals

aintains balance#

)ater # *alts

cids # ases


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Other Renal Functions

luconeo%enesis- in .rolon%ed astin%

$enin re%ulates

ryt'ro.oietin - $C .roduction

cti&ation o &itamin 3


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Other Urinary System Organs

Urinary bladder tem.orary stora%e or urine

aired ureters trans.orts urine4 5idneys to bladder

Uret'ra trans.orts urine4 bladder out o t'e body


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Urinary System Organs

Figure 25.1a


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Kidney Location and External Anatomy

$etro.eritoneal .osition in su.erior lumbar re%ion

$i%'t 5idney- lo6er t'an t'e let

Ureters, renal blood &essels, lym.'atics, 7 ner&es enter 7

exit at t'e hilum

$enal ca.sule ibrous ca.sule4 .re&ents outside o

5idneys rom inection

di.ose ca.sule cus'ions, 'olds 5idnesy in .lace4 ra.id

6t loss 7 .tosis (dro..ed 5idney"

$enal ascia outer layer o dense ibrous connecti&e

tissue4 anc'ors 5idney 6it'in t'e body


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Kidney Location and External Anatomy

Figure 25.2a


7/41Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

nternal Anatomy

Figure 25.!"

1.

2.

3.

4.

5.

6. Afferent arteriole7. glomerulus

8. Efferent arteriole9. Peritubular

capillaries !asa recta 1".

11.

12.

13.



#lood and $er%e Su&&ly

bout 8 o systemic cardiac out.ut lo6s t'rou%'

5idneys/minute4 9 1200 ml

rterial lo6 into and &enous lo6 out o t'e

5idneys ollo6 similar .at's

:'e ner&e su..ly is &ia t'e renal .lexus

'LA('LA(InterActive Physiology ®:

Anatomy Re%ie)* &age 5



Renal +ascular 'ath)ay

Figure 25.!c



nternal Anatomy

Figure 25.!"

1.

2.

3.

4.

5.

6. Afferent arteriole7. glomerulus

8. Efferent arteriole9. Peritubular

capillaries# $asa recta 1".

11.

12.

13.



,he $e&hron

*tructural 7 unctional units o 5idneys

; 106 ne.'rons/5idney

1< lomerulus a tut o ca.illaries

2< renal tubule

C:, decendin% loo. o Henle, loo.,ascendin% loo. o Henle, 3C:, collectin% duct



,he $e&hron

o6man=s (%lomerular" ca.sule surrounds

%lomerulus

$enal cor.uscle t'e %lomerulus 7 o6man=s

ca.sule

o6man=s s.ace- s.ace bet6een %lomerulus 7

o6man=s ca.sule 6'ere iltrate is collected

'LA('LA( InterActive Physiology ®: Urinary- Anatomy Re%ie)* &ages /0


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,he $e&hron

Figure 25.a* "

1.

2.

Filtration slits allo6 iltrate to .ass into

o6man=s s.ace

:'in loo.- *im.le s>uamous- % &2"

permeable not solutes

C:- Cuboidal, micro&illi4 'eabsorbs

&2" ( solutes rom iltrate4 )rush

bor*er cells+?u@@yA

edullary Collectin% 3uct- Cuboidal,

permeable to ,ater ( urea

3C:- Cuboidal, scant micro&illi4secretion4 Bate 3C: 2 cell ty.es

:'ic5 loo., scendin% loo.- cuboidal, s'ortmicro&illi4 permeable to solutes esp -al, not to

6ater


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Late 3, 4 3ollecting ucts

2 Cell :y.es

1< ntercalated cells

Cuboidal cells, micro&illi

aintain acid-base balance by H+ secretion2< rinci.al cells- re%ulated by 'ormones

Cuboidal cells, no micro&illi

aintain 6ater- salt balance

edullary collectin% duct, re%ulate DureaE

'LA('LA( InterActive Physiology ®: Anatomy Re%ie)* &ages 1215* 110


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$e&hrons/ 2 ,y&es

1< Cortical ne.'rons- o6man=s ca.sule in cortex

a5e u. G o all ne.'rons

*urrounded by eritubular ca.illary beds

2< Iuxtamedullary ne.'rons- o6man=s J cortex-medulla

unction

Boo.s o Henle lie dee. in medulla

; t'in se%ments

Concentrate urine

*urrounded by Lasa $ecta


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3a&illary #eds

Figure 25.5a


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3a&illary #eds o6 the $e&hron

&ery ne.'ron 'as t6o ca.illary beds

lomerulus

eritubular ca.illaries or Lasa $ecta

ac' %lomerulus is#

Fed by an aerent arteriole

3rained by an eerent arteriole


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3a&illary #eds o6 the $e&hron

lomerulus is 'i%'#

rterioles are 'i%'-resistance &essels

erent arterioles ; diameters t'an eerent

arterioles

Fluids 7 solutes are orced out o blood 7 into

iltrate t'rou%'out entire len%t' o %lomerulus


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3a&illary #eds

Peritubular be*s/

Bo6-.ressure, .orous ca.illaries or absor.tion

rise rom eerent arterioles o cortical ne.'rons

m.ty into t'e renal &enous system

$asa recta / (a ty.e o .eritubular ca.illary bed"

rise rom eerent arterioles o uxtamedullary ne.'rons

Ca.illaries are lon%, strai%'t &essels

Concentrate urine

m.ty into t'e renal &enous system


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$e&hron Anatomy

Figure 25.5a


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+ascular Resistance in 7icrocirculation

lood .ressure M rom Gmm H% in renal arteries

to mm H% in renal &eins

$esistance in aerent arterioles#

rotects %lomeruli rom luctuations in systemic

blood .ressure

$esistance in eerent arterioles#

$einorces 'i%' %lomerular .ressure

$educes 'ydrostatic .ressure in .eritubularca.illaries


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8uxtaglomerular A&&aratus 98:A;

0aintains constant ' protects glomerulus from

changes in sstemic )P regulates sstemic )P

*ite 6'ere ascendin% loo. o Henle lies next to aerent

arteriole

Iuxta%lomerular (I" cells (or %ranular cells" in arteriole6alls

Bar%e, smoot' muscle cells

*ecrete renin

ec'anorece.tors


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0acula *ensa cells

:all, .ac5ed ascendin% tubule cells

Bie adacent to I cells

C'emorece.tors/osmorece.tors4 ?NaCl sensorsA

esan%lial cells#

Functions .oorly understood

Ha&e .'a%ocytic and contractile .ro.erties

'LA('LA(InterActive Physiology ®:

Anatomy Re%ie)- &age 1<


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Figure 25.<

cells or


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Filtration 7em"rane

et6een blood 7 o6man=s s.ace

:'ree layers

Fenestrated endot'elium o %lomerular ca.illaries

Lisceral membrane o %lomerular ca.sulepo*octes

asement membrane com.osed o used basallaminae o t'e ot'er layers


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Filtration 7em"rane ! layers

Figure 25.a

1.2.

!< Fused basementmembrane bet6een ot'er 2

layers


27/41


Filtration 7em"rane

'LA('LA( InterActive Physiology ®: Anatomy Re%ie)* &age 11

Figure 25.c


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7echanisms o6 Urine Formation

lood &olume ilters t'rou%' 5idneys O0P/day

Filtrate#

ll plasma com.onents exce.t protein

Urine#

Filtrate ater losin% 6ater, 6astes, ions


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7echanisms o6 Urine Formation

Urine ormation#

! maor .rocesses

1< lomerular

iltration 2< :ubular

reabsor.tion

!< :ubular*ecretion

Figure 25.=


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:lomerular Filtration

; eicient t'an ot'er ca.illary beds because#

Filtration membrane ; .ermeable

lomerular blood .ressure is 'i%'er

; net iltration .ressure

lasma .roteins not iltered4 maintain oncotic

.ressure inside ca.illaries


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$et Filtration 'ressure 9$F';

NF Q net iltration .ressure

&Pg glomerular h*rostatic pressure

% Q oncotic .ressure o %lomerular blood

Hc Q ca.sular 'ydrostatic .ressure

NF Q H% (% + Hc"

GG (!0 + 1G"


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$et Filtration 'ressure

Figure 25.0

NF QGG (!0 + 1G"


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:lomerular Filtration Rate 9:FR;

$olume of filtrate forme* per minute

Factors#

1< :otal surace area a&ailable or iltration

2< Filtration membrane .ermeability

3. -et filtration pressure

F$ directly .ro.ortional to t'e NF

C'an%es usually rom c'an%es in %lomerular blood

.ressure (%lomerular 'ydrostatic .ressure"


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Regulation o6 :lomerular Filtration

:'ree mec'anisms control t'e F$

ntrinsic system

1< $enal autore%ulation

xtrinsic system

2< Neural controls

!< Hormonal mec'anism (renin-an%iotensin system"


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Regulation o6 :lomerular Filtration- ntrinsic 3ontrols

utore%ulation#

yo%enic

; , constricts aerent arteriole

M , dilates aerent arteriole

Flo6-de.endent tubulo%lomerular eedbac5

acula densa o uxta%lomerular a..aratus

res.onds to DNaClE in iltrate

$esults rom too ast or too slo6 F$


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Regulation o6 :lomerular Filtration

t'e F$ is too 'i%'#

Needed substances not reabsorbed

Nutrients, electrolytes, etc< lost in t'e urine

t'e F$ is too lo6#

&eryt'in% is reabsorbed

)aste is 5e.t in blood, not excreted in urine


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Regulation o6 :FR- Extrinsic 3ontrols- $eural

utore%ulation mec'anisms .re&ail UNB**# Fi%'t or Fli%'t res.onse, lood loss, sytemic

c'an%es, etc< 7 t'en *N* o&errides autore%<

Catec'olamines released, constrict aerentarterioles, M F$4 blood s'unted to ot'er or%ans

)'en luid &olume restored, autore% restored,

normal F$


38/41


Regulation o6 :FR- Extrinsic- >ormonal-

Renin/ Angiotensin

M , M DNaClE in 3C:, *N* stimulation induces I cells to

release renin

I cells release renin an%iotensin an%iotensin

1< ; (&asoconstriction"

2< ldosterone release (; Na++, ; H20, ;"

!< 3H release, t'irst acti&ation, ; H20, ;

R< Constriction o eerent arteriole, M .eritubular ca.illary

'ydrostatic .ressure, ; luid bac5 in blood, ;

G< esan%ial cells contract, M F$

For systemic re%ulation o 7 luid &olume


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Other Factors A66ecting :FR

rosta%landins (2 and 2"- roduced in

5idneys4 Lasodilators .roduced in res.onse tosym.at'etic stimulation and an%iotensin 4 .rotect

5idneys

N- by 'eart 6it' ; , ; blood &olume4 M luid&olume by ; Na+ secretion

Nitric oxide &asodilator .roduced by t'e &ascular

endot'elium

denosine &asoconstrictor o renal &asculature


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Regulation o6 :FR

Figure 25.1?


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SCIT 1408 Applied Human Anatomy and Physiology II - Urinary System Chapter 25 A