1. the urinary system – an overview 2. embryonic...

1. The urinary system – an overview

2. Embryonic development – kidney systems

3. The urinary organs:

�kidneys and excretory passages of urine

�ureters

�urinary bladder

�male and female urethra

Urinary system

SPLANCHNOLOGY

Prof. Dr. Nikolai Lazarov

The urinary system

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� The urinary system, systema urinaria

� excretion of the end products

of the metabolic activities – urine

� The urinary organs, organa urinaria:

� kidney, ren:

� renal calyces – minor and major

� renal pelvis

� ureter, ureter

� urinary bladder, vesica urinaria

� urethra, urethra:

�male urethra, urethra masculina

� female urethra, urethra feminina

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Prof. Dr. Nikolai Lazarov 3

Embryonic development

� Embryonic origin – from common mesodermal ridge (intermediate mesoderm): � urogenital ridge

� mesonephric ridge – lateral part

� Kidney system:

� pronephros, Gr. pro-, earlier + nephros, kidney

� the earliest nephric stage in humans

� in the cervical region of the embryo

� nephrotomes – begin 4 we.

� induction by the intermediate mesoderm �

via transcription factors Lim-1 and Pax-2

� disappear by the end of the 4th we.

� mesonephros, Gr. “middle kidney” (Wolffian body)

� begin – 4 we., caudally to the pronephros

� mesonephric (Wolffian) duct

� metanephros, definitive (permanent) kidney

� appears in the 5th we. in the pelvis –metanephric diverticulum (ureteric bud)

� metanephric mesoderm – blastemao growth factors FGF-2, BMP-7 and LIF

� ureteric bud � collecting system (ducts)

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Embryonic development� Embryogenesis of the urinary bladder and urethra:

� anorectal canal – posterior part of the cloacal membrane

� urogenital sinus, sinus urogenitalis:

� the upper part � urinary bladder

o the allantois � urachus

� the middle portion

o the prostatic and membranous

parts of the male urethra

o the whole female urethra

� the lower (phallic) part

o the spongy part of the male urethra

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Kidney, ren

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� Kidney, ren (Gr. nephros):

� a paired organ

� excretory function:

� end metabolites

� excess water

� endocrine function:

� erythropoietin - red blood cell formation

� renin – control of blood pressure and volume

� 1,2,5-hydroxycholecalciferol –control of the calcium metabolism

� Kidneys in situ:

� in the lumbar region

� in the posterior abdominal cavity,

on the posterior abdominal wall

� in the retroperitoneal tissue

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Macroscopic anatomy

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� Kidney overview:

� shape – bean-shaped

� two extremities:

o superior and inferior extremity

� two surfaces and two margins:

o anterior and posterior surface

o lateral and medial margin

� renal hilum � renal sinus � renal calyces

� size:

� 10-13 (~12) cm long

� ~6 cm wide

� ~3 cm thick

� weight – 150 g (♂); 135 g (♀);

1/240 of the body mass

� color – reddish

� renal consistency – a parenchymal organ

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Topography of the kidney

� Renal surface projections:

� the posterior abdominal wall

� 12th thoracic vertebra

� 1st and 2nd lumbar vertebrae

� right kidney –1-2 cm inferior to the left

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Kidney attachments

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� Renal capsules:� renal capsule, capsula fibrosa

� adipose capsule �

pararenal fat

� renal fascia (of Gerota), fascia renalis – two layers

� prerenal fascia

� retrorenal fascia

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Imaging anatomy

CT and MRI at the level of renal hilum

� conventional radiography

� echography (ultrasonography)

� computed tomography (CT)

� magnetic resonance imaging (MRI)

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Renal relations

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� Kidney structure:

� the renal cortex, cortex renalis – 5-10 mm:

� outer reddish brown-colored part

� granular appearance:

o pars convoluta

o pars radiata (cortex juxtamedullaris)

o lobulus corticalis

� the renal medulla, medulla renalis:

� much lighter-colored inner part

� renal pyramids, pyramides renales – 7-20 (12):

o basis pyramidis

o papilla renalis � sinus renalis

o foramina papillaria � area cribrosa

� renal columns, columnae renales (Bertini)

� renal lobes, lobi renales

General renal structure

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� The nephron, nephronum – 1-2 million:

� renal corpuscle (of Malpighi), corpusculum renale (Malpighi)

� the renal tubules:� proximal (first) convoluted tubule,

tubulus contortus proximalis� U-shaped thin segment (loop of Henle),

tubulus atenuatus (ansa nephroni)o descending limb, pars descendenso ascending limb, pars ascendens

� distal (second) convoluted tubule, tubulus contortus distalis

� collecting tubule, tubulus renalis colligens:

o straight tubule (pars recta) and convoluted tubule (pars convoluta)

� Types of neuphrons:� cortical or subcapsular nephrons,

nephronum breve (corticale)

� intermediate, nephronum intermedium� juxtamedullary nephrons,

nephronum longum (juxtamedullare)

Microscopic anatomy

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� Renal corpuscle (of Malpighi), corpusculum renale (Malpighi) –number – 2 million, diameter 200 µm:

� cortical glomerulus (80%) andjuxtamedullary (20%)

� a tuft of capillaries, glomerulus– rete capillare glomerulare (mirabile)

� vascular pole, polus vascularis

� urinary pole, polus tubularis

� afferent arteriole, vas afferens

� efferent arteriole, vas efferens

�mesangium

� renal or Bowman’s capsule, capsula glomeruli (Bowman)

� visceral lamina, paries interna

� parietal lamina, paries externa

� capsular (urinary) space, lumen capsulae

Microscopic anatomy

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Blood-urine barrier

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� The kidney filtration apparatus –semipermeable barrier – glomerular filtrate = 170 l. primary urine:

� fenestrated capillary endothelium, lamina fenestrata

� endothelial cells, endotelocyti fenestrati

o 0.04-0.1 µm pores (fenestrations) with an absent diaphragm

� glomerular basement membrane, membrana basalis – 30 µm

� lamina rara interna

� lamina densa

� lamina rara externa

� visceral layer ofBowman’s capsule

� podocytes, podocyti – 20-30 µm

o pedicels (foot processes), cytotrabecules and cytopodia

o filtration slits – 20-30 nm

o filtration slit membrane

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The mesangium

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� Mesangium (Gr. mesos, middle, + angeion, vessel):� mesangial cells, mesangiocyti

� in islets, insulae perivasculares masangii� supporting role – produce the glomerular matrix� contractile and phagocytic function� contain receptors for angiotensin ІІ, ANF� synthesize IL-1 and PDGF

� extraglomerular mesangial (‘lacis’) cells – ‘polar cushion’; the juxtaglomerular apparatus

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The renal tubules

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� proximal convoluted tubule, tubulus contortus proximalis:

� length 15 µm; width 50-60 nm

� parts:� initial part, neck

� convoluted tubule, pars convoluta

� straight tubule, pars recta

� simple columnar epithelium� brush border � microvilli

� basal striations

� reabsorption of water and electrolytes, amino acids, sugarsand polypeptides

� distal convoluted tubule, tubulus contortus distalis:� shorter and wider

� parts:� straight segment, pars recta

� convoluted, pars convoluta

� simple cuboidal epithelium� striations � short microvilli

� reabsorption of Na, K and water

� juxtaglomerular apparatus

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The renal tubules

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� proximal convoluted tubule, tubulus contortus proximalis:

� length 15 µm; width 50-60 nm

� parts:� initial part, neck

� convoluted tubule, pars convoluta

� straight tubule, pars recta

� simple columnar epithelium� brush border � microvilli

� basal striations

� reabsorption of water and electrolytes, amino acids, sugarsand polypeptides

� distal convoluted tubule, tubulus contortus distalis:� shorter and wider

� parts:� straight segment, pars recta

� convoluted, pars convoluta

� simple cuboidal epithelium� striations � short microvilli

� reabsorption of Na, K and water

� juxtaglomerular apparatus

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� attenuated tubule (renal loop, loop of Henle), tubulus atenuatus (ansa nephroni):� in the medulla (pyramids)

� parts – U-shaped turn� pars descendens – 30 nm, simple squamous epithelium

� pars ascendens – 60 nm, simple cuboidal tocolumnar epithelium in the thick segment

� single microvilli

� reabsorption of Cl-

� collecting tubule, tubulus renalis colligens:� parts:

� arched collecting tubules,tubulus colligens arcuatus

� straight collecting tubules,tubulus colligens rectus

� simple cuboidal epithelium� light (CD) cells – aquaporin-1, 2 and 3

� dark (intercalated or IC) cells

� simple � bilayered (calyces) columnar epithelium

� basement membrane

� water reabsorption (ADH)

� small volume of hypertonic urine

The renal tubules

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Kidney as an endocrine organ

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� The juxtaglomerular apparatus:

� juxtaglomerular cells:

�modified smooth muscle cells in

the media of the afferent arteriole

� secretory granules (10-40 nm) – renin

� absent internal elastic membrane

� macula densa:

� taller columnar cells

o crowded nuclei

o signaling molecules � renin

� absent basement membrane

� extraglomerular mesangial (lacis) cells(Goormaghtigh cells) – erythropoietin

� interstitial cells – prostaglandins

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Blood supply of the kidney

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� Renal blood vessels:

� renal artery – 70% of the arterial blood:

� aa. interlobares, aa. arcuatae et aa. interlobulares � vas afferens

� accessory renal arteries – 30%

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Kidney segmentation� Renal segments:

� segmentum superius� segmentum inferius� segmentum anterius superius� segmentum anterius inferius� segmentum posterius

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Lymphatic drainage of the kidney

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� Periarterial

lymphatic network

� Perivenous

lymphatic network

� Lymphatic network

in the renal capsule

� left kidney –

lymphatic vessels

around aorta

� right kidney –

lymphatic vessels

around

inferior vena cava

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Nerve supply to the kidney

� Renal plexus:� parasynpathetic –

vagus nerve� sympathetic

� celiac and mesenteric ganglia

� somatosensory� thoracic and lumbar

spinal nerves

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Renal anomalies

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� Ectopic kidney:� renal hilum

� below L3 – lumbar, iliac and pelvic kidney

� above Th12 – thoracic

� unilateral andbilateral renal ectopia –horseshoe kidneyren atcuatus (1:600)

� cross fused renal ectopia

� congenital (inherited)

� acquired –movable kidney

� Absence of kidney

� Accessory kidney

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Excretory ducts of the kidney

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� Minor calyces, calycesrenalesminores:

� 8-9 in number

� fornix

� Major calyces, calyces renales majores:

� 2(3) in number

� Renal pelvis, pelvis renalis:

� in the renal sinus

� pelvis ampullaris et ramificans

� Forms of the excretory system:� embryonic

� fetal

� mature

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Ureter, ureter

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� Ureter, ureter:�muscular tube

� length 30 cm

�diameter 7-8 mm

� Anatomical parts: � abdominal part –

– retroperitoneal position

� pelvic part

� intramural part

� Three anatomical constrictions:

�diameter 3-4 mm

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Microscopic anatomy

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� tunica mucosa:

� lamina epithelialis– transitional epithelium

� lamina propria – 350-700 µm

� fibroelastic connective tissue

� lymphocytes and lymphatic follicles

� tunica muscularis – 750-800 µm:

� stratum longitudinale

� stratum circulare

� stratum longitudinale – lower ⅓

� tunica adventitia:� nerves

� loose connective tissue

� blood and lymph vessels

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The roentgen anatomy

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� Retrograde pyelography� Intravenous urography� Normal course of ureters� Three major forms of

the excretory tree� Ureteral abnormalities –

duplicated ureter

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Urinary bladder, vesica urinaria

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� Urinary bladder, vesica urinaria (Gr. cystis):� reservoir – collects urine,

120-230 (max. 500) ml

� on the pelvic cavity floor

� sphere- or pear-shaped

� Anatomical parts:� fundus, fundus vesicae

� neck, cervix vesicae

� body, corpus vesicae

� summit, apex vesicae �lig. umbilicale medianum

� Internal surface:� trigone, trigonum vesicae

� ostium ureteris

� ostium urethrae internum

� plica interureterica, uvula

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Imaging Anatomy

paramedian MRI

cystourethrography

retrograde ureteropyelography

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Microscopic anatomy

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� tunica mucosa – wrinkled or folded:

� lamina epithelialis – transitional epithelium

� lamina propria – 350-700 µm

� areolar connective tissue

� lymphocytes and lymph follicles

� tela submucosa – mucosal rugae, mucosal stroma

� tunicamuscularis–detrusormuscle

� internal longitudinal layer

� circular layer � m. sphincter vesicae

� external longitudinal layer

� tunica serosa (adventitia):

� superior-posterior surface– serosa

� loose connective tissue

� blood and lymph vessels

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Blood supply to the ureter and urinary bladder

� Blood supply:

� the ureter – branches from:

� a. renalis, a. testicularis

(ovarica), aorta abdominalis,

a. iliaca communis et

a. iliaca interna, a. rectalis

media, aa. vesicales inferiores

� the urinary bladder:

� a. vesicalis superior

� a. vesicalis inferior

� Venous drainage:

� ureter � homonymous veins �

inferior vena cava

� bladder �

plexus venosus vesicalis � v. iliaca int.

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Lymphatic drainage

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� Ureter:

� lymph nodes around abdominal aorta

� iliaclymph nodes

� Urinary bladder:

� internal iliac lymph nodes

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Innervation of the ureter and urinary bladder

� Ureter:� parasympathetic –

pelvic nerves� sympathetic

� nerves along the arteries

� somatosensory� Spinal nerves

� Urinary bladder –plexus vesicalis:� sympathetic

� plexus vesicalis

� parasympathetic� nn. pelvici

� somatosensory

� nerve fibers

of spinal origin

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Male and female urethra

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Male urethra

� Urethramasculina ~20 cm:

� intarmural part� prostatic part – 3 cm

� membranous part – 1-2 cm

� spongy (penile) part – 15 cm

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Microscopic anatomy

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� tunica mucosa:

� lamina epithelialis � transitional epithelium� pseudostratified

columnar epithelium� stratified squamous nonkeratinized – in the navicular fossa

� lamina propria – basement membrane; stroma� urethral glands (Littre); urethral lacunae (Morgagni)

� tunica muscularis – prostatic and membranous parts

� str. circulare � m. sphincter urethrae (externus)

� str. longitudinale

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Female urethra� Urethra feminina:

� ostium urethrae internum� ostium urethrae externum� length 3-4 cm� diameter 6-10 mm

� Microscopic anatomy:� tunica mucosa – longitudinal folds, urethral crest

� transitional epithelium� stratified squamous nonkeratinized epithelium� stratified squamous keratinized� lamina propria

o urethral glandso urethral lacunae

� tela submucosa� tunica spongiosa

� tunica muscularis� internal layer,

smooth muscle fibers� external layer,

striated muscle fibers

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Thank you ....

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1. the urinary system – an overview 2. embryonic...

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