Excretory system
Systema urinarium
Kidneys
Renes
Overview of excretory system
Upper excretory system
• Kidney (Ren)
– Nephron (Nephron)
– Collecting tubuli (Tubuli colligentes)
Lower excretory system
– Renal calices (Calices renales)
– Renal pelvis (Pelvis renalis)
• Ureter (Ureter)
• Urinary bladder (Vesica urinaria)
• Urethra (Urethra)
Kidney = Ren
• greek nephros
– pl. nephroi
• 150 g
• facies anterior +
posterior
• extremitas superior +
inferior
• margo medialis +
lateralis
• hilum renale
• sinus renalis
• capsula fibrosa
• lobi renales
Kidney – internal composition
• cortex:
– labyrinthus
– columnae renales
protrudes into medulla
• medulla:
– pyramides renales →
papillae renales
• area cribrosa + foramina
papillaria
– zona interna
– zona externa
• stria interna + externa
– radii medullares
protrudes into cortex
http://doctorstock.photoshelter.com/image/I0000zjcQLOxaHqY
Position, fixation and renal covers
Transversal section at the level Th1
Impressions on the anterior face of kidney
Suprarenal gland
Liver
Suprarenal gland
Stomach
lien
Flexura coli dextra
Posterior kidney side impressions
Kidney syntopy,
posterior side
Left
Diaphragm
Right
Kidney
microscopic
structure
• nephron
• interstitium
• vessels
Nephron
•
•
•
•
•
Renal corpuscle
Proximal tubule
Intermediary tubule
Distal tubule
Juxtaglomerular
apparatus
Renal corpuscle
Corpusculum renale Malpighi
• glomerulus (vascular convolut)
– polus vascularis (vascular pole)
– arteriola glomerularis afferens (wider)  arteriola
glomerularis efferens (narrower)
– fenestrated (70-100 nm) capillaries w/o diaphragma
• capsula glomerularis (Bowmans pouch)
– stratum parietale = parietal sheet
• Flat single layer epithelium (epitheliocyti parietales)
– stratum viscerale = visceral sheet
• podocytes
• spatium capsulare / urinarium
– polus urinarius / tubularis (urinary pole)
Renal corpuscle
Corpusculum renale Malpighi
• podocytes
– trabecules (cytotrabeculae) – primary
extensions
– pedicles (cytopediculi) – secondary
extensions
• Basal membrane
• mesangium (mesangium)
– Mesangial cells (mesangiocyti)
• phagocyting, contractile and mitoting cells
– mesangial matrix
Philtration barrier
= barrier blood-urine (glomerular philter)
3 layers:
• Endothelium of glomerular capillaries
• Basal membrane
– lamina rara interna + lamina densa (collagen IV,
laminin fibronectin, heparan sulphate) + lamina rara
externa
• Pedicles of podocytes
– Interdigitates among and form philtration cleft covered
by cleft membrane – diaphragma rimae (nefrin)
- Other issues: size (10 nm) and substance charge
→ water permeable, low molecular substances
→ retain plasma proteins and blood cells
Mesangial cells (mesangiocyti)
• File of cells of mesenchyme origin
• Adjacent to capillary wall of glomerulus
A: intraglomerular (= pericytes)
– contractile function – got receptors for angiotenzin II
and natriuretic factor (ANF)
– Skeletal function
– Synthesis of mesangial matrix and collagen
– fagocytosis
– proliferation
B: extraglomerular mesangial cells
– Form part of juxtaglomerular apparatus
Renal tubules 1.
• Proximal tubule (tubulus proximalis)
– Convoluted part (pars convoluta)
– Straight part (pars recta)
• middle / intermediate tubule (tubulus
intermedius)
– Descending part (pars descendens)
– Ascending part (pars ascendens)
• Distal tubule (tubulus distalis)
– Convoluted part (pars convoluta)
• macula densa
– Direct part (pars recta)
Proximal tubule
• Single layer cuboid epithelium
– Brush border on luminal side
– Striation on basal side = basolateral labyrinth
(Na+-K+-ATPase)
– Rich on mitochondria
• Resorption of NaCl and water (80-95 %),
glucose, aminoacids and proteins
– Na+ into cell passively, from the cell activelly
Middle / intermediate tubule
= thin part of Henle loop
• Flat cells, poor on organels
– Descending branch permeable for water
– Ascending branch not permeable for water
• juxtamedular nephrons have long Henle
loop
– Countercurrent system (together with vasa
recta)
Henle loop
Ansa nephroni Henlei
• Formed by 3 morphological parts:
– pars recta tubuli proximalis
– tubulus intermedius
– pars recta tubuli distalis
• Different length:
– Juxtamedullary nephrons have long loop
– Cortical nephrons have short loop
• 5x more compared to long ones
• parts:
–
–
–
–
Thick descending loop
Thin descending loop
Thin ascending loop
Thick ascending loop
Distal tubule
• Single layer cuboid epithelium
– Cells are smaller compared to proximal one
– Lack of brush border
– Striation on basal side = basolateral labyrinth
(Na+-K+-ATPase)
– Rich on mitochondrias
• Back resorption of Na+ and secretion of K+
– Regulated by aldosterone
• macula densa
– chemoreceptors (Cl- and Na+)
Juxtaglomerulární aparát
Complexus juxtaglomerularis
• granulární buňky arteriola afferens + efferens
= juxtaglomerulární buňky (Juxtaglomerulocytus)
– přeměněné svalové buňky tunica media
– mechanoreceptory
– inervace sympatikem
– tvoří renin
• macula densa distálního kanálku (epitheliocytus maculae
densae)
– asi 30 štíhlých buněk
– opačná polarita buněk
– chemoreceptory
• mesangiální buňky (mesangiocytus extraglomerularis
Goormaghtighi; Lacis cell)
• funkce:
– regulace krevního tlaku – systém renin-angiotensin-aldosteron
(RAA)
Interstitium
• Connected with basal lamina of tubules and
vessels
• cortical x medullary
• Cell elements
• Fibroblasts similar cells
• Cells with adipous particle
• macrophages, pericytes
• Non cellular elements
• proteoglycans, glycoproteins, interstitial fluid
Kidney tubules 2.
• Connecting tubule (tubulus reuniens)
– Arch between distal and collecting tubule
• Collecting tubule (tubulus colligens)
– Sigle layer cuboid epithelium
• Papillary duct (ductus papillaris)
– Single layer columnar epithelium
– Opens on area cribrosa papillae renalis
Collecting ducts (Tubuli colligentes)
• Principal cells (Epitheliocytus principalis)
– Concentration of urine
– Light cytoplasm, round nuclei
• Interstitial cells (Epitheliocytus intercalatus)
– Secretion of H+ in exchange for K+
– Reabsorption of bicarbonate (karboanhydrasis)
• Regulation of water resorption – antidiuretic
hormone (adiuretin, vasopressin) = ADH
– aquaporins
Kidney – arterial supply
• a. renalis
– Paired visceral branch from aorta abdominalis at the
level of discus intervertebralis L1/2, left one higher
• a. renalis accessoria (30 %)
– Branch of aorta abdominalis caudally, from a. iliaca
communis / interna
• Blood flow 1,2-1,3 l blood/min
• Arteries are terminal type = no arterio-arterial
anastomoses
→ 5 kidney segments
Segments / parts of kideny
•
•
•
•
•
segmentum superius
segmentum anterius superius
segmentum anterius inferius
segmentum inferius
segmentum posterius
– Proper vessel
(r. posterior a. renalis)
Kidney – arterial supply 2.
a. renalis → r. anterior → 4 segmental branches
→ r. posterior for 1 posterior segment
aa. segmentales → aa. lobares (cca 12)
→ 2-3 aa. interlobulares
→ 2 vertically running aa. arcuatae
→ aa. interlobulares
→ arteriolae glomerulares afferentes
→ capillaries of glomerulus (glomerulus)
• Pressure in glomerular systém high (55 mmHg)
→ arteriolae glomerulares efferentes
→ peritubular capillary mesh or arteriolae rectae along
intermediary tubules of juxtaglomerular nephrons
• Pressure in the systém of peritubular plexus is low (15 mmHg)
Kidney – venous drainage
• vv. stellatae (from surface)
• + venulae rectae (along intemediary lubuls
of juxtaglomerular nephrons)
• + peritubular capillary plexus →
→ vv. interlobulares → vv. arcuatae → vv.
interlobares → v. renalis → v. cava inferior
• Portal system (= rete mirabile)
– 2 concomitant serially arranged capillary
bedstreams
• strong veno-venous anastomoses
Kidney – lymph flow
• 3 lymph plexus
– peritubular, subcapsular and from capsula adiposa
• nodi lymphoidei lumbales
Kidney – innervation
• plexus renalis
– autonomous, viscerosensitive
– from ganglion coeliacum + plexus coeliacus
– from ganglion aorticorenale from n. splanchnicus
minor/imus and plexus aorticus abdominalis
Resorptive function of kidneys
• Countercurrent multiplicatory system / mechanism
– Different permeability of canals for water and salts
– Drainage of interstitium by vasa recta
• Hormonal regulation
– RAA: renin → (from angiotensinogen in blood)
angiotenzin I  (enzyme ACE on endotelium in lungs)
angiotenzin II  (in kidney cortex)
– aldosterone
– ADH
– ANF
• Other kidney hormones: erytropoetin, kalcitriol
Countercurrent
multiplicatory
mechanism of
kidney
Countercurrent
multiplicatory
mechanism of kidney
Kidney HE
Kidney Van Gieson
Kidney development
• předledvina = pronephros
– nefunkční, „otevřená“
• prvoledvina = mesonephros
– základ pohlavní žlázy
• konečná ledvina = metanephros
http://www.indiana.edu/~anat550/urrepanim/animations/gonad_dev.swf
http://meded.duke.edu/symbrio/site/index.html#
Kidney development
• Origin from intermedial mesoderm
• Longitudinal elongation of mesoderm on both
sides of dorsal aorta → urogenital crest →
nephrogenic strand → origin of urinary / genital
system
– Genital crest → origin of genital system
4 foundations of urinary system
• Metanephrogenic blastemanefron
(Bowmans pouch and tubules)
• Ureteric bud
– collecting tubules → ureter
• vessels – branches from dorsal aorta
• Cells from crista neuralis (regulation, secretion)
Pronephros
pl. pronephroi
• Forms excretory systém in cyclostomatous
species (lamprey)
• In human first description by Janosik
• Stalks of cranial 12-13 somites
• Since 21st day (4 somites) in cervical region
• rudimentary, early ceases
• tubuli pronephrici
• ductus pronephricus premains until next stage
Mesonephros
• Excretory system of Chondrychties and fishes
• Basic is nephrogenic blastem (intermediary
mesoderm)
• Pouch elongates towards ductus mesonephricus
Wolffi
– At the stage of 27-28 somites ingrowth to
cloaca
• Since approx. 23rd day till the end of 3rd month
• corpuscula mesonephrica (glomerulus) + tubuli
mesonephrici
• Caudal part of tubuli → basis of caput
epididymidis
Ductus mesonephricus Wolffi
• Originate in intermediary mesoderm
• Blindly from up as outlet pronephroi
• Caudally continues as outlet
mesonephroi
• Finishes growth and opens into cloaca
• Fundamental for development of male
reproduction outlet pathway
• From caudal part is formed diverticulum
metanephricum (ureteral bud)
Ductus mesonephricus
Male Wolffi
reproductive
(Prvoledvinný vývod)
organs
Vesiculous
gland
• ♀ ureterální pupen → trigonum vesicae,
Prostate
ureter,
pelvis renales, calices, ductus
papilalles, tubuli colligentes
– vývojové rudimenty: epoophoron, ductusPenis
Bulbo-urethral
longitudinalis Gartneri
gland
Urethra
• ♂ totéž + vývodní pohlavní cesty (ductus
epididymidis, ductus deferens glandulae
vesiculosae,
ductus ejaculatorius)
Deferantial duct
Scrotum
Epididymis
testis
Metanephros = Definitive kidney
• blastema metanephrogenicum (metanephrogenic
blastem) of 3rd-5th lumbar somite
– Development start at the end of 5th week
– During development there is relative ascension
• Ureteral bud growth in blastem – reciprocal
induction (necessary close contact)
• Ureteral bud → ureter, pelvis renalis, calices,
calliculi, papillary ducts till collecting tubules
• Metanephrogenic blastem – nephron
• Relative ascension: 5th-9th week
• Functional since 9th week
Nephrogenesis
8th week
• Direct collecting tubules
→ from these round collecting ducts
→ its end induce metanephritic bodies
• Spheroid body → line body → sigmoid body →
connection to branch of ureteric bud
• Maturation of kidney body
• Distance from glomerulus from medulla makes up for
age
– Oldest are juxtamedulary nephrons
• Ends of collecting tubules elongate into metanephric
tubules and joins collecting ducts
• Into opposing ends of metanephric tubule invaginate
glomeruli
Development termination
• Terminal position in 9th week (termination
of ascension)
• 10th-23rd week:
– Quantity of glomeruli increases and reaches
its border (800 000 – 1 000 000)
• Kidneys of fetus are separated into visible
lobes
– Cessation during childhood
• After delivery growth of interstitium,
elongation of tubules and Henles loops
Developmental defects
• Atypical shapes (lobular, horse shoe, doubled, sigmoid,
arcuate…)
• cystic, polycystic kidneys
• Agenesis of kidney
• Dysplasia of kidneys
• ectopia of kidneys (ren dystopicus)
Polycystic kidneys
Prenatal diagnostics
• Kidneys are visible by ultrasound since 12th-15th week
• The goal is recognition of developmental defects
– dysplasia of kidneys, damage to kidney function, lung
hypoplasia
• Oligohydramnion
– Primary lesion of kidneys, secondarily of lungs (part of Potter
syndrome )
• Cystic dysplasia of kidney
– Increased risk of Wilms tumor incidence (nephroblastoma)
• Hydronephrosis
– Origin in obstructive nephropathias
Kidney examination
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•
•
•
native x-ray picture
sonography
Excretive urography
ascendent pyelography
scintigraphy
clearence
CT, MR
Ultrasound of kidney
http://lunar.thegamez.net/medical/ultrasound-sonography/ru-ultrasound-image-description-kidney-640x480.jpg
http://www.genesis-ultrasound.com/images/renal-ul-image.jpg
Scintigraphy of kidney
SPECT – frontální řez
http://www.kcsolid.cz/zdravotnictvi/klinicka_kapitola/nef/nef-26/nef-26-text.htm
http://www.kcsolid.cz/zdravotnictvi/klinicka_kapitola/nef/nef-5/nef-5-text.htm
http://www.jpalliativecare.com/viewimage.asp?img=IndianJPalliatCare_2013_19_1_58_110239_u6.jpg
http://www.kidneystoners.org/wpcontent/uploads/2012/02/pediatrickidney-stone-CT.jpg
MRI
Kidney diseases
• developmental defects
• cysts (solitary x polycystic kidney)
• ren migrans (migrating kidney)
•glomerulonephritis
• pyelonephritis
• nephrolitiasis
• renal colic
• hydronephrosis
• diabetes mellitus – nephropathy
• tumors
• Grawitz (solitary metastasis)
• Wilms (autosomally inherited – children)
• stenosis a. renalis
Nephrolitiasis
Kidney diseases
• Acute pyelonephritis
• Diabetic nephropathy