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Urinary system
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
SPLANCHNOLOGY
The urinary system
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
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 – blastema
o growth factors FGF-2, BMP-7 and LIF
ureteric bud
collecting system (ducts)
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Embryonic development
Embryogenesis of the urinary bladder and urethra:
anorectal canal – posterior part of the cloacal membrane
urogenital sinus, sinus urogenitalis:
the upper part
o the allantois
urinary bladder
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Kidney, ren
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Macroscopic anatomy
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Kidney attachments
Renal capsules:
renal capsule, capsula fibrosa
adipose capsule
pararenal fat
renal fascia (of Gerota),
fascia renalis – two layers
prerenal fascia
retrorenal fascia
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov
9
SPLANCHNOLOGY
Imaging anatomy
conventional radiography
echography (ultrasonography)
computed tomography (CT)
magnetic resonance imaging (MRI)
CT and MRI at the level of renal hilum
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Renal relations
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
General renal structure
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Microscopic anatomy
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 descendens
o 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)
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Microscopic anatomy
Renal corpuscle (of Malpighi),
corpusculum renale (Malpighi) –
number – 2 million, diameter 200 µm:
cortical glomerulus (80%) and
juxtamedullary (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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Blood-urine barrier
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 of
Bowman’s capsule
podocytes, podocyti – 20-30 µm
o pedicels (foot processes),
cytotrabecules and cytopodia
o filtration slits – 20-30 nm
o filtration slit membrane
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
The mesangium
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
The renal tubules
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, sugars
and 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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
The renal tubules
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, sugars
and 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
Prof. Dr. Nikolai Lazarov
18
SPLANCHNOLOGY
The renal tubules
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 to
columnar 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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Kidney as an endocrine organ
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Blood supply of the kidney
Renal blood vessels:
renal artery – 70% of the arterial blood:
aa. interlobares, aa. arcuatae et
aa. interlobulares
vas afferens
accessory renal arteries – 30%
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Kidney segmentation
Renal segments:
segmentum
segmentum
segmentum
segmentum
segmentum
superius
inferius
anterius superius
anterius inferius
posterius
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Lymphatic drainage
of the kidney
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Nerve supply to the kidney
Renal plexus:
parasynpathetic –
vagus nerve
sympathetic
celiac and mesenteric
ganglia
somatosensory
thoracic and lumbar
spinal nerves
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Renal anomalies
Ectopic kidney:
renal hilum
below L3 – lumbar,
iliac and pelvic kidney
above Th12 – thoracic
unilateral and
bilateral renal ectopia –
horseshoe kidney
ren atcuatus (1:600)
cross fused
renal ectopia
congenital (inherited)
acquired –
movable kidney
Absence of kidney
Accessory kidney
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Excretory ducts of the kidney
Minor calyces,
calyces renales minores:
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Ureter, ureter
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Microscopic anatomy
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
The roentgen anatomy
Retrograde pyelography
Intravenous urography
Normal course of ureters
Three major forms of
the excretory tree
Ureteral abnormalities –
duplicated ureter
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Urinary bladder, vesica urinaria
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Imaging Anatomy
cystourethrography
retrograde ureteropyelography
paramedian MRI
Prof. Dr. Nikolai Lazarov
SPLANCHNOLOGY
Microscopic anatomy
tunica mucosa – wrinkled or folded:
lamina epithelialis – transitional
lamina propria – 350-700 µm
epithelium
areolar connective tissue
lymphocytes and lymph follicles
tela submucosa – mucosal rugae,
mucosal stroma
tunica muscularis – detrusor muscle
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
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.
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Lymphatic drainage
Ureter:
lymph nodes around
abdominal aorta
iliac
lymph nodes
Urinary bladder:
internal iliac
lymph nodes
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Male and female urethra
Prof. Dr. Nikolai Lazarov
SPLANCHNOLOGY
Male urethra
Urethra masculina ~20 cm:
intarmural part
prostatic part – 3 cm
membranous part – 1-2 cm
spongy (penile) part – 15 cm
Prof. Dr. Nikolai Lazarov
SPLANCHNOLOGY
Microscopic anatomy
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
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
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 glands
o urethral lacunae
tela submucosa
tunica spongiosa
tunica muscularis
internal layer,
smooth muscle fibers
external layer,
striated muscle fibers
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Thank you ....
Prof. Dr. Nikolai Lazarov
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