Early Filtrate ProcessingEarly Filtrate Processing

Tubular ReabsorptionTubular Reabsorption

�� By passive diffusionBy passive diffusion

�� By primary active transport: SodiumBy primary active transport: Sodium

�� By secondary active transport: Sugars and By secondary active transport: Sugars and Amino AcidsAmino Acids

Reabsorption PathwaysReabsorption Pathways

�� There are two reabsorption pathways:There are two reabsorption pathways:

1. the transcellular pathway (>>)1. the transcellular pathway (>>)

2. the paracellular pathway2. the paracellular pathway

Reabsorpsi FiltratReabsorpsi Filtrat

�� Trancellular pathway : Through luminal Trancellular pathway : Through luminal and basolateral membranes of the tubular and basolateral membranes of the tubular cells into the interstitial space and then cells into the interstitial space and then into the peritubular capillaries. into the peritubular capillaries.

�� Paracellular pathway : through the tight Paracellular pathway : through the tight junctions into the lateral intercellular junctions into the lateral intercellular junctions into the lateral intercellular junctions into the lateral intercellular space. space.

�� Water and certain ions use both Water and certain ions use both pathways, especially in the proximal pathways, especially in the proximal convoluted tubule. convoluted tubule.

Diffusion of WaterDiffusion of Water

�� Water diffuses from the lumen through the Water diffuses from the lumen through the tight junctions into the interstitial space:tight junctions into the interstitial space:

�� 1. Water will move from its higher 1. Water will move from its higher concentration in the tubule through the concentration in the tubule through the concentration in the tubule through the concentration in the tubule through the tight junctions to its lower concentration in tight junctions to its lower concentration in the interstitium. the interstitium.

�� 2. Water will also move through the 2. Water will also move through the plasma membranes of the cells that are plasma membranes of the cells that are permeable to water permeable to water

Sodium ReabsorptionSodium Reabsorption

Lumen

Cells

PUMP: Na/K ATPase

Sodium

Potassium

Plasma

Potassium

Chloride

Water

Tubular SecretionTubular Secretion

�� Protons (acid/base balance)Protons (acid/base balance)

�� PotassiumPotassium

�� Organic ionsOrganic ions

�� Transport Maximum (Tm)Transport Maximum (Tm)For most actively reabsorbed solutes, the For most actively reabsorbed solutes, the amount reabsorbed in the PCT is limited only by amount reabsorbed in the PCT is limited only by the number of available transport carriers for the number of available transport carriers for that specific substance. This limit is called the that specific substance. This limit is called the transport maximum, or Tm. transport maximum, or Tm.

If the volume of a specific solute in the filtrate If the volume of a specific solute in the filtrate If the volume of a specific solute in the filtrate If the volume of a specific solute in the filtrate exceeds the transport maximum, the excess exceeds the transport maximum, the excess solute continues to pass unreabsorbed through solute continues to pass unreabsorbed through the tubules and is excreted in the urine.the tubules and is excreted in the urine.

Reabsorption: Receptors can LimitReabsorption: Receptors can Limit

Figure 19-15: Glucose handling by the nephron

Potassium SecretionPotassium Secretion

Lumen

Cells

PUMP: Na/K ATPase

Sodium

Potassium

Plasma

Potassium

Chloride

Water

Gambaran seluler dari tubulus Gambaran seluler dari tubulus renalisrenalis

�� Tubulus proximal: simple cuboidal cells Tubulus proximal: simple cuboidal cells (brush border cells ok terdapat microvilli)(brush border cells ok terdapat microvilli)

�� Thin loop of henle: simple squamous cell, Thin loop of henle: simple squamous cell, highly permeable to water not to solutehighly permeable to water not to solutehighly permeable to water not to solutehighly permeable to water not to solute

�� Thick ascending loop of henle & early Thick ascending loop of henle & early distal tubule: cuboidal cells, highly distal tubule: cuboidal cells, highly permeable to solutes, particularly NaCl but permeable to solutes, particularly NaCl but not to waternot to water

�� Late distal tubule and cortical collecting Late distal tubule and cortical collecting duct: cuboidal cells has two distinct duct: cuboidal cells has two distinct function: function:

�� 1. principal cells; permeability to water 1. principal cells; permeability to water and solutes are regulated by hormones and solutes are regulated by hormones and solutes are regulated by hormones and solutes are regulated by hormones and,and,

�� 2. intercalated cells; secretion of hydrogen 2. intercalated cells; secretion of hydrogen ion for acid/base balancingion for acid/base balancing

�� Medullary collecting duct; principal cells; Medullary collecting duct; principal cells; hormonally regulated permeability to hormonally regulated permeability to water and ureawater and urea

�� The final processing of filtrate in the The final processing of filtrate in the late distal convoluted tubule and late distal convoluted tubule and collecting ducts comes under direct collecting ducts comes under direct physiological control in response to physiological control in response to changing physiological conditions and changing physiological conditions and hormone levels. hormone levels. hormone levels. hormone levels.

�� Membrane permeabilities and cellular Membrane permeabilities and cellular activities are altered in response to the activities are altered in response to the body's need to retain or excrete specific body's need to retain or excrete specific substances.substances.

Distal Tubule & Collecting DuctDistal Tubule & Collecting Duct

�� The Late Distal Tubule & CCT are The Late Distal Tubule & CCT are composed of principal cells & intercalated composed of principal cells & intercalated cellscells

�� Intercalated cells secrete hydrogen ions Intercalated cells secrete hydrogen ions �� Intercalated cells secrete hydrogen ions Intercalated cells secrete hydrogen ions into filtrateinto filtrate

�� Principals cells perform hormonally Principals cells perform hormonally regulated water & sodium reabsorption & regulated water & sodium reabsorption & potassium secretionpotassium secretion

Role of AldosteronRole of Aldosteron

�� Principal cells are permeable to sodium Principal cells are permeable to sodium ions and water only in the presence of ions and water only in the presence of Aldosterone & ADHAldosterone & ADH

�� Low level of Aldosterone result in little Low level of Aldosterone result in little �� Low level of Aldosterone result in little Low level of Aldosterone result in little basolateral sodium/potassium ATPase ion basolateral sodium/potassium ATPase ion pump activity & few luminal sodium & pump activity & few luminal sodium & potassium channelpotassium channel

�� Aldosteron increases the number of Aldosteron increases the number of basolateral Na/K pump and luminal Na basolateral Na/K pump and luminal Na & K channels& K channels

�� Since there are no basolateral K Since there are no basolateral K channel, K ion are secreted into the channel, K ion are secreted into the instead of returning to the interstitiuminstead of returning to the interstitiuminstead of returning to the interstitiuminstead of returning to the interstitium

�� Without an increase in water Without an increase in water permeability, the interstitial osmolarity permeability, the interstitial osmolarity increasesincreases

Role of ADHRole of ADH

�� Principals cells are permeable to water Principals cells are permeable to water only on the presence of ADHonly on the presence of ADH

Reabsorption in Proximal TubuleReabsorption in Proximal Tubule

�� Glucose and Amino AcidsGlucose and Amino Acids

�� 67% of Filtered Sodium67% of Filtered Sodium

�� Other ElectrolytesOther Electrolytes

65% of Filtered Water65% of Filtered Water�� 65% of Filtered Water65% of Filtered Water

�� 50% of Filtered Urea50% of Filtered Urea

�� All Filtered PotassiumAll Filtered Potassium

Countercurrent multiplier mechanismCountercurrent multiplier mechanism

�� The opposing flow and opposite The opposing flow and opposite activities of descending & ascending activities of descending & ascending segments of loop of henle is called the segments of loop of henle is called the segments of loop of henle is called the segments of loop of henle is called the countercurrent multiplier mechanismcountercurrent multiplier mechanism

DIFFERENCES IN THE NEPHRON LOOP

The descending

limb:-

1. Highly permeable

to water

2. Relatively

impermeable to

sodiumsodium

The ascending limb:-

1. Impermeable

to water

2. Actively transports

sodium out of the

filtrate

REGULATION OF URINE CONCENTRATIONREGULATION OF URINE CONCENTRATION

�� Medullary countercurrent systemMedullary countercurrent system

�� VasopressinVasopressin

Medullary countercurrent systemMedullary countercurrent system

�� Osmotic gradient established by long Osmotic gradient established by long loops of Henleloops of Henle

�� Descending limbDescending limb�� Descending limbDescending limb

�� Ascending limbAscending limb

Descending limbDescending limb

�� Highly permeable to waterHighly permeable to water

�� No active sodium transportNo active sodium transport

Ascending limbAscending limb

�� Actively pumps sodium out of tubule to Actively pumps sodium out of tubule to surrounding interstitial fluidsurrounding interstitial fluid

�� Impermeable to waterImpermeable to water�� Impermeable to waterImpermeable to water

COUNTERCURRENT MAKESCOUNTERCURRENT MAKESTHE OSMOTIC GRADIENTTHE OSMOTIC GRADIENT

300

450

600

750

From

Proximal

Tubule

To Distal

TubuleCortex

Medulla300

450

600

750

100

250

400

550Active750

900

1050

1200

1200

750

900

1050

1200

1200

550

700

850

1000

1000

Active

Sodium

Transport

Passive

Water

Transport

Long Loop

of Henle

THE OSMOTIC GRADIENT CONCENTRATES THE URINE THE OSMOTIC GRADIENT CONCENTRATES THE URINE WHEN VASOPRESSIN (ANTI DIURETIC HORMONE [ADH]) WHEN VASOPRESSIN (ANTI DIURETIC HORMONE [ADH])

IS PRESENTIS PRESENT

From

Distal

Tubule

Cortex

Medulla300

450

600

750

300

400

550

700

Interstitial Fluid

Collecting

Duct750

900

1050

1200

1200

700

850

1000

1100

1200

Pores

Open

Passive Water Flow

WHEN VASOPRESSIN (ANTI DIURETIC HORMONE WHEN VASOPRESSIN (ANTI DIURETIC HORMONE [ADH]) IS ABSENT A DILUTE URINE IS PRODUCE[ADH]) IS ABSENT A DILUTE URINE IS PRODUCE

From

Distal

Tubule

Cortex

Medulla300

450

600

750

100

100

100

100

Interstitial Fluid

Collecting

Duct750

900

1050

1200

1200

100

100

100

100

100

Pores

Closed

No Water Flow

Out of Duct

“Countercurrent Multiplication System”“Countercurrent Multiplication System”

�� Summary:Summary:–– “Countercurrent” refers to “Countercurrent” refers to opposite directions of flow within opposite directions of flow within the descending and ascending the descending and ascending the descending and ascending the descending and ascending loop of Henle.loop of Henle.

–– “Multiplication” refers to the “Multiplication” refers to the multiplied increase in osmolarity multiplied increase in osmolarity towards apex of medullary towards apex of medullary pyramids as filtrate continues to pyramids as filtrate continues to flow into nephron.flow into nephron.

“Countercurrent Multiplication System”“Countercurrent Multiplication System”

�� Summary:Summary:

–– Results in the formation of an Results in the formation of an osmotic gradient.osmotic gradient.

–– Enables formation of a hypotonic Enables formation of a hypotonic filtrate by the nephron.filtrate by the nephron.

–– Assists of osmosis of water into Assists of osmosis of water into the ascending limb (loop of the ascending limb (loop of Henle) and into collecting ducts Henle) and into collecting ducts (requires ADH).(requires ADH).

UreterUreter

�� Merupakan saluran yang menghubungkan Merupakan saluran yang menghubungkan ginjal ke kandung kemih, yang ginjal ke kandung kemih, yang merupakan lanjutan renal pelvis.merupakan lanjutan renal pelvis.

�� Panjang 10Panjang 10--12 inchi.12 inchi.�� Panjang 10Panjang 10--12 inchi.12 inchi.

�� Ureter memasuki kandung kemih melalui Ureter memasuki kandung kemih melalui bagian posterior dengan cara menembus bagian posterior dengan cara menembus otot detrusor di daerah trigonum kandung otot detrusor di daerah trigonum kandung kemihkemih

�� Dinding ureter terdiri dari otot polos & Dinding ureter terdiri dari otot polos & dipersarafi oleh saraf simpatis & dipersarafi oleh saraf simpatis & parasimpatis.parasimpatis.

�� Kontraksi peristaltik pada ureter Kontraksi peristaltik pada ureter ditingkatkan oleh perangsangan ditingkatkan oleh perangsangan parasimpatis & dihambat oleh parasimpatis & dihambat oleh parasimpatis & dihambat oleh parasimpatis & dihambat oleh perangsangan simpatis.perangsangan simpatis.

�� Peristalsis dibantu gaya gravitasi akan Peristalsis dibantu gaya gravitasi akan memindahkan urine dari ureter ke memindahkan urine dari ureter ke kandung kemih.kandung kemih.

Kandung KemihKandung Kemih(Vesica Urinaria)(Vesica Urinaria)

�� Berfungsi menampung/menyimpan urine Berfungsi menampung/menyimpan urine sementara.sementara.

�� Terdiri atas :Terdiri atas :

1.1. Badan (corpus) = bagian utama kandung Badan (corpus) = bagian utama kandung 1.1. Badan (corpus) = bagian utama kandung Badan (corpus) = bagian utama kandung kemih dimana urine terkumpul. kemih dimana urine terkumpul.

2.2. Leher (kollum) = lanjutan dari badan Leher (kollum) = lanjutan dari badan yang berbentk corong, berjalan secara yang berbentk corong, berjalan secara inferior dan anterior ke dalam daerah inferior dan anterior ke dalam daerah segitiga urogenital & berhubungan segitiga urogenital & berhubungan dengan urethra.dengan urethra.

Dinding kandung kemih :Dinding kandung kemih :

�� 3 lapisan otot polos (detrusor 3 lapisan otot polos (detrusor muscle)muscle)

�� Mucosa : ‘transitional epithellium’Mucosa : ‘transitional epithellium’

�� Dinding : tebal & Dinding : tebal &

berlipat saat berlipat saat berlipat saat berlipat saat

kandung kemih kosong.kandung kemih kosong.

�Trigone – tiga pembukaan :

Dua dari ureter dan Satu ke urethra

PersarafanPersarafan

�� N. pelvikus yang berhubungan dengan N. pelvikus yang berhubungan dengan medulla spinalis melalui pleksus sakralis medulla spinalis melalui pleksus sakralis (S2 dan S3).(S2 dan S3).

�� Saraf sensorik = regangan dinding Saraf sensorik = regangan dinding �� Saraf sensorik = regangan dinding Saraf sensorik = regangan dinding kandung kemih kandung kemih →→ refleks berkemih.refleks berkemih.

�� Saraf motorik = parasimpatis Saraf motorik = parasimpatis →→

berakhir pada sel ganglion yang berakhir pada sel ganglion yang terletak dalam dinding kandung terletak dalam dinding kandung kemih kemih untuk mensarafi otot detrusor.untuk mensarafi otot detrusor.

UrethraUrethra

�� Saluran berdinding tipis yang Saluran berdinding tipis yang memindahkan urine dari kandung kemih memindahkan urine dari kandung kemih ke luar tubuh degan gerak peristalsis.ke luar tubuh degan gerak peristalsis.

�� Panjang : pria=8 inchi, wanita=1½ inchi.Panjang : pria=8 inchi, wanita=1½ inchi.

Pengeluaran urine diatur oleh dua katup Pengeluaran urine diatur oleh dua katup �� Pengeluaran urine diatur oleh dua katup Pengeluaran urine diatur oleh dua katup (sphincters)(sphincters)

–– Internal urethral sphincter (tanpa Internal urethral sphincter (tanpa sadari/involuntary)sadari/involuntary)�� External urethral sphincter External urethral sphincter (disadari/voluntary)(disadari/voluntary)

Berkemih (Micturition/VoidingBerkemih (Micturition/Voiding))

• Kedua katup (sphincter) otot harus terbuka agar dapat berkemih

• Internal urethral sphincter : direlakskan setelah peregangan kandung kemih

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

•Pengkatifan ini berasal dari impulse dikirim ke spinal cord dan kemudian balik melalui saraf pelvic splanchnic

•External urethral sphincter : harus direlakskan secara sadar

Neuroanatomy of Neuroanatomy of Lower Urinary TractLower Urinary Tract

MICTURITION REFLEX

Bladder fills

Stretch receptors

+

Spinal Cord

Parasympathetic

nerve

Bladder contractsInternal urethral

sphincter opens

Only the external urethral sphincter is controlled voluntarily

+

Spinal Cord

Figure 26.21

Urination: Micturation reflexUrination: Micturation reflex

Detrusor

Hypogastic nerves (L1, L2, L3)

Sympathetic

Rugae folds

α-Adrenergic

receptors

Figure 19-18: The micturition reflex

Sacral

Parasympathetic

(S1, S2, S3)

Pelvic nerve

Visceral afferent pathway

Sacral

Pudential nerves

Skeletal muscle

Fundus