notes on urinary system for undergraduate medical students

1. URINARY SYSTEM -1
Kidneys
Urethra
Dr.Prajkta Kulkarni
Assistant Professor,Rachanasharir(Anatomy)
Tilak Ayurved Mahavidyalaya
Pune
Email-prajktakulkarni2005@gmail.com

2. The urinary system consists of-
Kidneys
Ureters
Urinary bladder
Urethra
This system plays major role in
The excretion of waste products from
The metabolism.

3. KIDNEYS
No.-2
Also known as ‘Renes’
Colour- reddish brown
Shape- bean shaped,lobulated
Size –
Length-11cm
Breath- 6cm
Thickness-3 cm
Weight-
Males-150 gm
Females-135 gm

4. Location-
•Retroperitoneal organ.
•Located on either side of the vetebral column on the posterior abdominal wall,
From vertebral level T12 to L3.
Left kidney is nearer to the median plane than the right kidney.
Right kidney is at lower level than the left one.
The upper poles of both the kidneys are covered with the corresponding
Suprarenal gland.

5. Features-
2 poles,2 borders,2 surfaces
Poles-
Upper and lower poles
a)Upper pole –
covered with corresponding adrenal gland.
b)Lower pole-
narrow,closely related with the ureters.
Borders-
1.Lateral border- convex
2.Medial border- concave ,shows hilum in the middle.

6. Surfaces-
1.Anterior surface- some what convex, with many visceral relations.
2.Posterior surface- somewhat flat.
Contents of renal hilum – from before backwards- VAP
1.Renal vein
2.Renal artery
3.Renal pelvis
Along with lymphatics,nerves and paranephric fat.

7. Coverings of kidney-
1.Fibrous capsule-
formed by condensation of fibrous stroma of kidney.
covers the entire organ.
2.Perinephric fat-
occupies interval between fibrous capsule and renal fascia.
fat is more along borders of kidneys.
3.Renal fascia-
formed by condensation of extraperitoneal connective tissue around the kidneys.
continuous laterally with fascia transversalis.
4.Paranephric fat-
occupies interval between renal fascia and anterior layer of thoracolumbar fascia .
more on posterior surface of lower part of kidney.

8. RELATIONS –
ANTERIOR-
Partially covered with peritoneum.
A)Right Kidney –
1.Suprarenal – non-peritoneal, includes upper pole and upper part of medial border
of kidney.
2.Duodenal –non-peritoneal,related to 2nd part of duodenum.

9. 3.Hepatic –
peritoneal ,includes upper ¾ th of anterior surface, related to right lobe of
liver,separated by hepatorenal pouch (Morrison’s ).
4.Colic –
non-peritoneal,related to right colic flexure.

10. B)Left kidney-
1.Suprarenal –non-peritoneal,overlapped by suprarenal gland.
2.Splenic – peritoneal,related to renal impression of spleen.
3.Gastric – triangular peritoneal area,related to posteroinferior surface of stomach
separated by cavity of lesser sac. Lienorenal ligament is attached
along the junction of gastric and splenic areas.
4.Pancreatic –non-peritoneal,related with body of pancreas and splenic vessels.
5.Colic – non-peritoneal,related to left colic flexure and descending colon.
6.Jejunal – occupies large peritoneal area ,related to few coils of jejunum.

11. POSTERIOR RELATIONS –
Common for both kidneys mostly.
Upper part-
From within outwards –
1.Diaphragm arising from medial and
lateral arcuate ligaments.
2.Costodiaphragmatic recess of the
corresponding pleura.
3.11 th and 12th ribs –left side
12 th rib- right side only

12. LOWER PART-
From medial to lateral side –
1.Psoas major, quadratus lumborum, transversus abdominis
2.Paranephric fat
3.Deep to thoracolumbar fascia and in front of quadratus lumborum,these pass
laterally and downwards from above downwards-
a)subcostal nerve and vessels
b)iliohypogastric nerve
c)ilioinguinal nerve
d)4th lumbar artery ,on right side only.

13. STRUCTURE OF NEPHRON

14. Nephron structure –
Outer cortex and inner medulla.
Cortex-contains renal columns and cortical arches.
Medulla – consists of 18 renal pyramids, apex of which projects into wall of renal
sinus- renal papilla
Each papilla is perforated by 16-20 ducts of Bellini and is received by a minor calyx.
Nephron is the functional unit of the kidney.1 million in no.
Nephron or uriniferous tubule has 2 parts- 1) secreting 2)collecting
Functions- 3
1.filtration, 2)selective re-absorption , 3)secretion

16. .
NEPHRON – 2 parts –
•Renal corpuscle- filtration
•Renal tubule - selective re-absorption
a)Renal corpuscle – (malpighian body)- located in cortical arches ,contains the
Bowman’s capsule with glomerular plexus of capillaries.
Bowman’s capsule- dilated end of renal tubule.Invaginated by glomerular plexus.
consists of a parietal layer and visceral layer,separated by
capsular space,which is filled with glomerular filtrate.
-parietal layer lined by single layer of continuous flattened epithelium.
-visceral layer lined by polyhedral cells ,podocytes

17. Glomerular plexus of capillaries – lobulated tuft of capillaries ,formed by the
Afferent and efferent arterioles.
RENAL TUBULE-
a)Proximal convoluted tubule (PCT)-
lined by single layer of columner epithelium
b)Loop of Henle-
U shaped,descending thin segment (flattened epithelium),
ascending thick segment (cubical epithelium)
c)Distal convoluted tubule- (DCT)-
lined by cuboidal epithelium (single layer),terminates in collecting tubule via
junctional tubule.

18. Collecting tubule –enter renal pyramids as ducts of Bellini – renal papillae- minor calyx
Major calyx-renal pelvis
Ligaments –
Lienorenal ligament- from left kidney between junction of gastric and splenic areas to
the spleen.
Blood supply - Renal artery
Venous drainage – efferent arteriole- interlobular vein-arcuate vein-interlobar-lobar-
renal vein-IVC
Lymphatics- lateral aortic lymph nodes
Nerve supply- sympathetic-renal plexus
parasympathetic- vagus nerve

19. Applied anatomy-
1. Nephritis
2.horseshoe-shaped kidney
3.Polycystic kidney
4.Kidney stone (renal calculus )
Renal angle- angle between lower border of 12th rib and lateral border of erector
spinae

20. FEMALE URETHRA
Length – 4cm
Width-6mm
Begins from internal urethral orifice,passes downwards and forwards,pierces
Perineal membrane ,opens into the vestibule and about 2.5 cm behind the
Glans clitoridis.
Glands – urethral,paraurethral, greater vestibular glands.
Applied anatomy-
Infections of female bladder are common due to the shortness of vagina.

21. MALE URETHRA
Common passage for urine and semen.
Extends from internal urethral orifice at apex of trigone to the external urethral
Orifice close the tip of glans penis.
Total length- 18-20 cm
3 parts-
a)Prostatic – 3cm
b)Membranous -2cm
c)spongy- 15 cm
Lumen –prostatic part- cresentic
membranous- irregular/stellate
spongy- transverse
at external orifice- sagittal

22. FEMALE
Female urethra

23. Male urethra

24. Features –
1.Prostatic part-
widest,most dilatable part,3 cm long.when urethra empty ,anterior and posterior
walls come in contact.
2.Features in posterior wall –
a)Urethral crest- median longitudinal mucous fold,produced by insertion of trigonal
muscle of ureter.
b)Colliculus seminalis- rounded elevation at middle of the crest.Has 3 orifices-
prostatic utricle in the middle and ejaculatory ducts on each side of utricle.

25. •Prostatic utricle- 6mm long,extends upwards and backwards from colliculus,behind
median lobe of prostate.utricle surrounded by fibromascular coat,lined by mucous
membrane and numerous mucous glands.
•2 ejaculatory ducts –each 2cm long,formed by union of seminal vesicle and vas
deferens.
passing posterolateral to median lobe ,opens at colliculus,on each side of utricle.
•Prostatic sinuses- 2 mucous gutters on each side of crest,receive openings of ducts of
prostate gland.
Relations of prostatic part – in front- isthmus of prostate
on each side- lateral lobe of prostate
behind –median lobe in upper part
continuity of 2 lateral lobes in lower part

26. 2.Membranous part-
narrowest part ,5mm in diameter
Course-runs downwards and forwards,from prostate to upper surface of bulb
of penis.It pierces the perineal membrane 2.5 cm behind lower border of
symphysis pubis.
Anterior wall is more prolonged than the posterior wall.
Anterior wall- 2cm
Posterior wall- 1.25 cm
Relations-
Surrounded by spincter urethrae.
On each side-bulbo- urethral gland and duct.
In front- deep dorsal vein of penis.

27. 3.Spongy part-
present In corpus spongiosum.15 cm long.
passes through bulb ,body,glans penis and end sat external urethral orifice close
to tip of the glans.
2 dialatations-
a)intrabulbar fossa within bulb of penis- 3 cm long,has ducts of bulbourethral
glands.
b)Terminal fossa in glans penis – lined by squamous epithelium-1.25 cm
In between these 2 dialatations, calibre is 6 mm.
Features –spongy part-
•Urethral glands (Littre’s glands)-simple,tubular,mucous glands- open in spongy
part.
•Urethral lacunae- pit like mucous recessess.mouth guarded by mucous fold –
valvule of Guerin.

28. Structure – from outside to inside-
a)muscular- derived from detrusor,consists of outer circular and inner longitudinal
layer of smooth muscle.
b)Submucous –of erectile muscular tissue.
c)mucous- variations in different parts-
1.Above colliculus-lined by transitional epithelium.
2.From colliculus to the commencement of terminal fossa – lined by columner
epithelium.
3.Terminal fossa and external urethral orifice-lined by squamous epithelium.
Spincters – internal – invoulntary,surrounds internal urethral orifice.
external-voluntary,derived from sphincter urethrae,which surrounds
membranous urethra.

29. Blood supply- inferior vesical,middle rectal,internal pudendal,urethral branch of artery
to bulb of penis.
Venous drainage- corresponding veins
Nerve supply- autonomic and somatic nerves
Lymphatics- prostatic and membranous parts by- internal and external iliac nodes
spongy- deep inguinal nodes
Applied anatomy-
a)Hypospadias- condition in which urethra opens on undersurface of penis instead
of tip.
b)Epispadias- condition in which urethra opens on dorsal surface of penis