Urinary systemUrinary system

2 Kidneys.2 Kidneys. 2 ureters.2 ureters. Urinary bladder.Urinary bladder. Urethera.Urethera.

KidneyKidney CortexCortex---Dark brown and granular.---Dark brown and granular. Medulla---Medulla---6-12 pyramid-shape regions (renal pyramids)6-12 pyramid-shape regions (renal pyramids)

The base of pyramid is toward the cortex (corticomedullary The base of pyramid is toward the cortex (corticomedullary border)border)

The apex (renal papilla) toward the hilum that perforated by The apex (renal papilla) toward the hilum that perforated by 12 openings of the ducts of Bellini in region called area 12 openings of the ducts of Bellini in region called area cribrosa . The apex is surrounded by minor calyx.cribrosa . The apex is surrounded by minor calyx.

Pyramids are separated by cortical columns of Pyramids are separated by cortical columns of BertinBertin 3or4 minor calyces3or4 minor calyces join to form 3or 4 major calyces that join to form 3or 4 major calyces that

form renal pelvis.form renal pelvis.

A hemisected A hemisected vew of the vew of the kidneykidney

Cortical archCortical arch Renal corpuscles (red dots).Renal corpuscles (red dots). Convoluted tubules (cortical labyrinth).Convoluted tubules (cortical labyrinth). Medullary rays (cortical continuation of pyramids).Medullary rays (cortical continuation of pyramids). NB. Lobe of the kidney is formed of :NB. Lobe of the kidney is formed of :

a- Renal pyramid.a- Renal pyramid.

b-Cortical columns.b-Cortical columns.

c-Cortical archc-Cortical arch

*Each medullary ray with part of the cortical labyrinth *Each medullary ray with part of the cortical labyrinth surrounding it form kidney lobule.surrounding it form kidney lobule.

Uriniferous Uriniferous tubuletubule

Uriniferous tubuleUriniferous tubule

Is the functional unit of the kidney.Is the functional unit of the kidney. Is formed of:Is formed of:

1- Nephron1- Nephron..

2-Collecting tubule.2-Collecting tubule. They are densely packed.They are densely packed. They are separated by thin stroma and basal They are separated by thin stroma and basal

lamina.lamina.

NephronNephron

There are 2 types:There are 2 types: a-Cortical nephrons.a-Cortical nephrons. b-Juxtamedullary nephrons.b-Juxtamedullary nephrons.*It is formed of :*It is formed of : 1-Renal corpuscle.1-Renal corpuscle. 2-Proximal tubule.2-Proximal tubule. 3-Thin limbs of Henle’s loop.3-Thin limbs of Henle’s loop. 4-Distal tubule4-Distal tubule

Renal corpuscleRenal corpuscle GlomerulusGlomerulus (tuft of fenestrated capillaries) (tuft of fenestrated capillaries) Bowman’s capsuleBowman’s capsule (Parietal layer, urinary or (Parietal layer, urinary or

glomerular space and visceral layer or podocytes).glomerular space and visceral layer or podocytes). Mesangial cellsMesangial cells (intraglomerular & (intraglomerular &

extraglomerular).extraglomerular).

Renal cortexRenal cortex

Renal corpuscleRenal corpuscle

Filtration barrierFiltration barrier

EndothelialEndothelial wall of the capillaries.wall of the capillaries. The basal laminaThe basal lamina (inner and outer laminae rarae (inner and outer laminae rarae

and middle lamina densa).and middle lamina densa). Visceral layer of Bowman’s capsule (podocytes)Visceral layer of Bowman’s capsule (podocytes) Podocytes have primary (major) processes and Podocytes have primary (major) processes and

secondary (minor) processes (pedicles).secondary (minor) processes (pedicles). Between pedicles (on the surface of capillaries) Between pedicles (on the surface of capillaries)

there are there are filtration slitsfiltration slits that have slit diaphragm that have slit diaphragm

Proximal tubuleProximal tubule It has 2 regions:It has 2 regions:

1-Pars convoluta1-Pars convoluta (Proximal convoluted tubule). (Proximal convoluted tubule).

2-Pars recta2-Pars recta (descending thick limb of Henle’s loop). (descending thick limb of Henle’s loop).

It is composed of simple cuboidal epith.with It is composed of simple cuboidal epith.with acidophilic cytoplasm. The cells have striated or acidophilic cytoplasm. The cells have striated or brush border and lateral interdigitations. They have brush border and lateral interdigitations. They have well-defined basal lamina.well-defined basal lamina.

Cell of Cell of proximal proximal

tubuletubule

Thin limb of Henle’s loopThin limb of Henle’s loop

It has 3 regions:It has 3 regions:

1-Descending thin limb.1-Descending thin limb.

2-Henle’s loop.2-Henle’s loop.

3-Ascending thin limb.3-Ascending thin limb.

NB. It is longer in juxtamedullary nephron than NB. It is longer in juxtamedullary nephron than in cortical nephron.in cortical nephron.

* It is composed of simple squamous epith.* It is composed of simple squamous epith.

Renal medullaRenal medulla

Distal tubuleDistal tubule It has 3 regions:It has 3 regions:1-Ascending limb of Henle’s loop1-Ascending limb of Henle’s loop (low cuboidal epith.). (low cuboidal epith.).2-macula densa2-macula densa (tall &narrow cells). (tall &narrow cells).3-Pars convoluta3-Pars convoluta (distal convoluted tubule) formed of low (distal convoluted tubule) formed of low

cuboidal epith.cuboidal epith.NB. Because distal convoluted are much shorter than NB. Because distal convoluted are much shorter than

proximal convoluted tubules, any section of renal cortex proximal convoluted tubules, any section of renal cortex presents many more sections of proximal convoluted presents many more sections of proximal convoluted tubules.tubules.

*Distal tubules drain into collecting tubules.*Distal tubules drain into collecting tubules.*Aldosterone hormone increase the active rebsorbtion of *Aldosterone hormone increase the active rebsorbtion of

sodium from the lumen of tubule into interstitium.sodium from the lumen of tubule into interstitium.

Distal tubule cellsDistal tubule cells..

Juxtaglomerular apparatusJuxtaglomerular apparatus

Juxtaglomerular apparatusJuxtaglomerular apparatus

It has 3 components:It has 3 components: A-The macula densaA-The macula densa of distal tubule. of distal tubule. B-Juxtaglomerular cellsB-Juxtaglomerular cells of afferent of afferent

glomerular arteriole (modified smooth muscle glomerular arteriole (modified smooth muscle of tunica media). They secrete of tunica media). They secrete renin,angiotensin-converting enzyme and renin,angiotensin-converting enzyme and angiotensin.angiotensin.

C-The extraglomerular C-The extraglomerular mesangial cellsmesangial cells..

Juxtaglomerular Juxtaglomerular apparatusapparatus

Collecting tubulesCollecting tubules Are composed of simple cuboidal epithelium.Are composed of simple cuboidal epithelium. They aren’t part of nephron.They aren’t part of nephron. They have 3 regions:They have 3 regions:1-Cortical.1-Cortical.2-Medullary.2-Medullary.3-Papillary3-Papillary (ducts of Bellini) they open in area of (ducts of Bellini) they open in area of

cribrosa.cribrosa.*They are formed of: a-principle cells. *They are formed of: a-principle cells. And b-intercalated cells.And b-intercalated cells.*They are impermeable to water except in presence of *They are impermeable to water except in presence of

antidiuretic hormone.antidiuretic hormone.

Cells of collecting tubuleCells of collecting tubule

Renal interstitiumRenal interstitium

It is a very flimsy, scant amount of CT contains.It is a very flimsy, scant amount of CT contains. 1-Fibroblasts.1-Fibroblasts. 2-Macrophages.2-Macrophages. 3-Interstitial cells3-Interstitial cells (their nuclei are elongated and (their nuclei are elongated and

they contain lipid droplets). They secrete medullipin they contain lipid droplets). They secrete medullipin I, which is converted in the liver into medullipin II, I, which is converted in the liver into medullipin II, that lowers blood pressure.that lowers blood pressure.

CalycesCalyces

Each calyx accepts urine from the renal papilla Each calyx accepts urine from the renal papilla of a renal pyramid.of a renal pyramid.

They are lined with transitional epith., lamina They are lined with transitional epith., lamina propria and smooth muscle.propria and smooth muscle.

Minor calyces merge to form major calyces Minor calyces merge to form major calyces (with same lining tissue as minor calyces).(with same lining tissue as minor calyces).

Major calyces open into renal pelvis.Major calyces open into renal pelvis.

Renal papilla and minor calyxRenal papilla and minor calyx..

UreterUreter

1.Mucosa1.Mucosa is formed of transitional epith. And is formed of transitional epith. And lamina propria.lamina propria.

2.Muscularis2.Muscularis (muscular coat) is formed of 2 (muscular coat) is formed of 2 layers of smooth muscle:layers of smooth muscle:

A-Inner longitudinal.A-Inner longitudinal.

B-Outer circular.B-Outer circular.

* * 3.Adventitia 3.Adventitia (fibrous CT covering).(fibrous CT covering).

UreterUreter

Urinary bladderUrinary bladder

It has the same structure as the ureter EXCEPT:It has the same structure as the ureter EXCEPT: The dome-shaped cells have plaques (rigid, The dome-shaped cells have plaques (rigid,

thickened regions of plasmalemma)thickened regions of plasmalemma) Between plaques there are normal cell membrane Between plaques there are normal cell membrane

(interplaque regions).(interplaque regions). It has 3 layers of smooth muscle, inner and outer It has 3 layers of smooth muscle, inner and outer

longitudinal and middle circular.longitudinal and middle circular. Its outer covering is serosa.Its outer covering is serosa.

Urinary bladderUrinary bladder

Female UrethraFemale Urethra

Female urethra is short and lined by :Female urethra is short and lined by :

1-Transitional epith. Near the bladder.1-Transitional epith. Near the bladder.

2-Pseudostratified columnar epith. And stratified 2-Pseudostratified columnar epith. And stratified squamous non-keratinized epith.squamous non-keratinized epith.

3-Subepth.fibroelastic CT that contains glands of 3-Subepth.fibroelastic CT that contains glands of Littre (mucus secreting glands).Littre (mucus secreting glands).

4-Smooth muscle (inner longitudinal and outer 4-Smooth muscle (inner longitudinal and outer circular layer).circular layer).

Male UrethraMale Urethra It is long and is divided into 3 regions:It is long and is divided into 3 regions:

1-The prostatic urethra—lined with transitional epith.1-The prostatic urethra—lined with transitional epith.

2-Membranous urethra---lined with pseudustratified 2-Membranous urethra---lined with pseudustratified columnar and stratified columnar epith.columnar and stratified columnar epith.

3-Penile (spongy) urethra---lined with pseudostratified 3-Penile (spongy) urethra---lined with pseudostratified columnar, stratified columnar and stratified columnar, stratified columnar and stratified squamous non-keratinized epith.squamous non-keratinized epith.

* Its lamina propria contains mucus secreting glands * Its lamina propria contains mucus secreting glands of Littre.of Littre.