THE URINARY SYSTEMTHE URINARY SYSTEM

dr. Sri Lestari Sulistyo Rini, dr. Sri Lestari Sulistyo Rini, M.ScM.Sc

The urinary system :

Ginjal terletak retroperitonealGinjal terletak retroperitonealSebuah ginjal 135-150 gr.Sebuah ginjal 135-150 gr.Ginjal terletak retroperitonealGinjal terletak retroperitonealSebuah ginjal 135-150 gr.Sebuah ginjal 135-150 gr.

Ginjal menerima 20-30% cardiac output

Aliran darah ke ginjal 1-1,5 L / mnt

Darah yang difiltrasi 180 L / hr

125 ml/mnt

Renal Function1. Elimination of Waste Products 2. Regulation of Fluid Balance3. Regulation of Acid-Base Balance4. Nutrient Balance : - electrolytes : Na+, K+, Cl-, Ca++,Mg++

- amino acids, glucose, proteins vitamin5. Elimination, Detoxification of Drug and Toxins6. Endocrine Function : - erytropoietin

- vitamin D metabolism - renin

Nefron Unit fungsional ginjal

- Sebuah ginjal terdiri dari + 1 juta nefron- Nefron : - Glomerulus

- Tubulus

Struktur NefronStruktur Nefron

Afferent

Arteriole Efferent

Arteriole

The NEPHRON: The Functional Renal Unit

Urine formation Eliminasi produk sisa metabolik Urea, Kreatinin, Asam urat, Sulfat,

Nitrat, Phosphat, dll.

Proses :1. Filtrasi glomerulus2. Reabsorpsi tubulus3. Sekresi tubulus4. Ekskresi

Ekskresi = Filtrat – reabsorpsi + sekresi

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Steps in Urine Formation

1) Glomerular Filtration

2) Tubular Reabsorption & Secretion

3) Water Reabsorption (Conservation)

Urine Formation Preview

How the Kidney Works

Pgc gc Pt

Filtrasi Glomerulus

Filtrasi glomerulus

Filtration Membrane• Fenestrated endothelium

• 70-90nm pores exclude blood cells

• Basement membrane• proteoglycan gel, negative

charge excludes molecules > 8nm

• blood plasma 7% protein, glomerular filtrate 0.03%

• Filtration slits• podocyte arms have pedicels

with negatively charged filtration slits, allow particles < 3nm to pass

Filtrasi Glomerulus

Reabsorpsi dan Sekresi Tubulus

Proximal TubulusReabsorpsi 80% air dan garamReabsorpsi semua glukosa, asam aminoReabsorpsi protein, urea, asam urat, bicarbonatSekresi ion Hidrogen, asam-basa organik

ReabsorpsiAktif : glukosa, asam amino, natrium, dllPasif : air dan urea

Transport maximum ( Tm) maksimum substansi yang di reabsorpsi per unit waktu

PCT Nutrient (glucose, amino acids) reabsorption = Normally 100% returned via cotransport with Na+

Transport maximum (Tm)

• Reabsorption will return solutes to the blood

• Binding sites for transport can become saturated at high levels

• Solutes not reabsorped are lost in the urine

• Vitamin C is reabsorped unless plasma values are so high that transporters can’t reabsorb any more – then excess vitamin C lost in the urine

Loop of Henle• Descending limb permeabel terhadap air• Ascending limb impermeabel terhadap

air reabsorpsi Na dan Cl

Tubulus DistalReabsorpsi Na, Cl dan airADH mempengaruhi permeabilitas terhadap

airReabsorpsi dan sekresi KaliumAldosteron mempengaruhi reabsorpsi

Natrium dan sekresi Kalium

Mekanisme Countercurrent

Renal RegulationRenal RegulationRenal RegulationRenal Regulation

Saraf simpatis Saraf simpatis arteriol aferen & eferen arteriol aferen & eferen vasokonstriksi, RBF menurun vasokonstriksi, RBF menurun

GFR menurunGFR menurun

Hormonal Hormonal Renin-Angiotensin Renin-Angiotensin AldosteronAldosteron ADHADH Atrial Natriuretic PeptideAtrial Natriuretic Peptide

Renal Autoregulation of GFR

BP constrict afferent arteriole, dilate efferent

• BP dilate afferent arteriole, constrict efferent

• Stable for BP range of 80 to 170 mmHg (systolic)

• Cannot compensate for extreme BP

Glomerular Filtration Rate (GFR)

• Renal autoregulation– Regulation of NFP– Macula densa

• Cells of DCT• Slow filtrate flow, low

osmolality (low Na, Cl) causes dilation of afferent arterioles

• High flow, high osmolality causes contraction of JGA cells, vasoconstriction

Duktus kolegentesDuktus kolegentes Reabsorpsi Na Reabsorpsi Na

dan Cl dan Cl dipengaruhi ADHdipengaruhi ADH

HormonesHormones

•AldosteroneAldosterone– Acts on distal convoluted tubule Acts on distal convoluted tubule

cells to stimulate active transport cells to stimulate active transport of 3 molecules of Naof 3 molecules of Na++ out of out of tubule (reabsorption) for every 2 tubule (reabsorption) for every 2 molecules of K molecules of K ++ brought into brought into tubule (secretion)tubule (secretion)

– Water from tubule lumen follows Water from tubule lumen follows NaNa++ by osmosis into blood by osmosis into blood

•Antidiuretic hormone (ADH)Antidiuretic hormone (ADH)– Acts to increase the number of Acts to increase the number of

aquaporins (water channels) in the aquaporins (water channels) in the collecting duct membranescollecting duct membranes

– Collecting ducts travel through Collecting ducts travel through hyperosmotic medullahyperosmotic medulla

– Higher levels of ADH increase the Higher levels of ADH increase the number of aquaporins allowing number of aquaporins allowing water to leave the duct and urine water to leave the duct and urine volume decreasesvolume decreases

Homeostatic

Control

involving

Aldosterone

Formation of Water Pores: Mechanism of Vasopressin Action

Formation of Water Pores: Mechanism of Vasopressin Action

Aldosterone Release: the Renin-Angiotensin Pathway

Factors affecting the release of ADH.

Factors affecting release of Atrial Natriuretic

Peptide.

Urine CompositionUrine Composition

• about 95% water

• usually contains urea, uric acid, and creatinine (break down product from creatine phosphate used up in muscles)

• may contain trace amounts of amino acids and varying amounts of electrolytes

• volume varies with fluid intake, diuretics (caffeine & alcohol) and environmental factors (heat, humidity)

Renal Function Test

Inulin Inulin ClearanceClearance

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Micturition Reflex

Body Water Balance

Circulating Volume control

Thirst

• Osmoreceptors detect changes decreases in blood volume and increases in blood solute levels

• They activate the thirst center in hypothalamus andADH-secreting cells

• Angiotensin II– formed from the interaction of renin (produced by the kidneys) with circulating angiotensinogen in the plasma– also acts on brain to promote thirst and ADH secretion

Urine pH ~ 6.0

Blood pH = 7.4

Blood [HCO3-] = 24 mM

Blood PCO2 = 40 mmHg

Plasma osmolality = 285 mOsm/kg water

Urine osmolality (depends upon hydration status) = 600 mOsm/kg water (note that this can vary between 50-1200 depending on water intake etc.)

Normal Urine & Blood

RENAL SYSTEM

CARDIOVASCULAR SYSTEM

RESPIRATORY SYSTEM

Acid-base balance

Gas exchange, ACE

Effective circulating volume

control, ECF osmolality, blood

pressure All of these are constantly changing,

trying to maintain HOMEOSTASIS!

Integration Renal – Cardiovascular – Respiratory System

TERIMA KASIHTERIMA KASIH