Tubular Reabsorption By passive diffusion By primary active transport: Sodium By secondary active transport: Sugars and Amino Acids

(1)

Early Filtrate Processing

(2)

Tubular 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 Acids Amino Acids

(3)

Reabsorption Pathways

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

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

2. the paracellular pathway 2. the paracellular pathway

(4)

Reabsorpsi Filtrat

(5)

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.

(6)

Diffusion 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

(7)

Sodium Reabsorption

Lumen

Cells

PUMP: Na/K ATPase

Sodium Potassium Plasma Potassium Chloride Water

(8)

Tubular Secretion

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

PotassiumPotassium

(9)

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.

(10)

Reabsorption: Receptors can Limit Reabsorption: Receptors can Limit

(11)

Potassium Secretion

Lumen

Cells

PUMP: Na/K ATPase

Sodium Potassium Plasma Potassium Chloride Water

(12)

Gambaran seluler dari tubulus

renalis

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 solute highly permeable to water not to solute highly permeable to water not to solute highly 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 water

(13)

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 balancing ion for acid/base balancing

Medullary collecting duct; principal cells; Medullary collecting duct; principal cells;

hormonally regulated permeability to hormonally regulated permeability to water and urea

(14)

(15)

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.

(16)

Distal 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 cells

cells

Intercalated cells secrete hydrogen ions Intercalated cells secrete hydrogen ions

into filtrate into filtrate

Principals cells perform hormonally Principals cells perform hormonally

regulated water & sodium reabsorption & regulated water & sodium reabsorption & potassium secretion

(17)

Role 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 & ADH

Aldosterone & ADH

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 channel

(18)

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 interstitium instead of returning to the interstitium instead of returning to the interstitium instead of returning to the interstitium

Without an increase in water Without an increase in water

permeability, the interstitial osmolarity permeability, the interstitial osmolarity increases

(19)

Role of ADH

Principals cells are permeable to water Principals cells are permeable to water

only on the presence of ADH only on the presence of ADH

(20)

(21)

Reabsorption in Proximal Tubule

Glucose and Amino AcidsGlucose and Amino Acids

67% of Filtered Sodium67% of Filtered Sodium

Other ElectrolytesOther Electrolytes

65% of Filtered Water 65% of Filtered Water

65% of Filtered Water65% of Filtered Water

50% of Filtered Urea50% of Filtered Urea

(22)

Countercurrent multiplier mechanism Countercurrent 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 mechanism

(23)

DIFFERENCES IN THE NEPHRON LOOP The descending limb:-1. Highly permeable to water 2. Relatively impermeable to sodium sodium

The ascending limb:-1. Impermeable

to water

2. Actively transports sodium out of the filtrate

(24)

REGULATION OF URINE CONCENTRATION REGULATION OF URINE CONCENTRATION

Medullary countercurrent systemMedullary countercurrent system

(25)

Medullary countercurrent system Medullary countercurrent system

Osmotic gradient established by long Osmotic gradient established by long

loops of Henle loops of Henle

Descending limbDescending limb

(26)

Descending limb

Highly permeable to waterHighly permeable to water

(27)

Ascending limb

Actively pumps sodium out of tubule to Actively pumps sodium out of tubule to

surrounding interstitial fluid surrounding interstitial fluid

Impermeable to waterImpermeable to water

(28)

COUNTERCURRENT MAKES COUNTERCURRENT MAKES

THE OSMOTIC GRADIENT THE OSMOTIC GRADIENT

300 450 600 750 From Proximal Tubule To Distal Tubule Cortex Medulla 300 450 600 750 100 250 400 550 Active 750 900 1050 1200 1200 750 900 1050 1200 1200 550 700 850 1000 1000 Active Sodium Transport Passive Water Transport Long Loop of Henle

(29)

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 PRESENT IS PRESENT From Distal Tubule Cortex Medulla 300 450 600 750 300 400 550 700 Interstitial Fluid Collecting Duct 750 900 1050 1200 1200 700 850 1000 1100 1200 Pores Open Passive Water Flow

(30)

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 Medulla 300 450 600 750 100 100 100 100 Interstitial Fluid Collecting Duct 750 900 1050 1200 1200 100 100 100 100 100 Pores Closed No Water Flow Out of Duct

(31)

“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.

(32)

“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).

(33)

Ureter

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.

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 kemih

(34)

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.

(35)

Kandung Kemih

(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.

(36)

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

(37)

Persarafan

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

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.

(38)

Urethra

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

(sphincters) (sphincters)

–

– Internal urethral sphincter (tanpa Internal urethral sphincter (tanpa sadari/involuntary)

sadari/involuntary)

External urethral sphincter External urethral sphincter (disadari/voluntary)

(39)

Berkemih (Micturition/Voiding

))

• Kedua katup (sphincter) otot harus terbuka

agar dapat berkemih

•Internal urethral sphincter : direlakskan

setelah peregangan kandung kemih

•Pengkatifan ini berasal dari impulse

dikirim ke spinal cord dan kemudian balik melalui saraf pelvic splanchnic

•External urethral sphincter : harus

(40)

Neuroanatomy of

Lower Urinary Tract

(41)

MICTURITION REFLEX Bladder fills Stretch receptors + Spinal Cord Parasympathetic nerve

Bladder contracts Internal urethral

sphincter opens

Only the external urethral sphincter is controlled voluntarily +

(42)

(43)

Urination: 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