describes all detail gross and microscopic anatomy of urinary system. it also covers major clinical aspects of urinary system.

1. Anatomy of Urinary System
Dr Laxman Khanal
BPKIHS
07-06-2013

2. Urinary system

3. Test yourself
• Where is the micturation center in the brain??
• Which of the following is found exclusively in the renal medulla?
a.Proximal convoluted tubules b. Distal convoluted tubules
c. Collecting ducts d. Thin loops of Henle
• Space for enlargement of bladder is ………….
a. Space of Reitzius b. Verumontanum
c. Urogenital raphe d. Pelvic space
• In kidney the less vascular area separating anterior and posterior
segment is known
as………….
a. Brodie’s line b. Canton’s line
c. Calot’s line d. Seshachalam’s line

4. T/F
• life expectancy of individual with a single kidney is the same
as those with two kidneys. ( T/F)
• Most common position of ectopic kidney is hypogastric region
of abdomen. ( T/F)
• Widest and most dilated part of urethra is………….
a. Membranous b. Prostatic
c. Penile d. External meatus

5. Objectives of class
• Key feature of kidneys
• Relationship of kidneys
• Renal fascia and its extension
• Macroscopic study of kidney
• Structure and function of urineferous tubules
• Key relation and constrictions of Ureters
• Support of bladder and its relationship
• Neural pathway of micturation

6. Functions
• Formation of urine
• Regulate volume and chemical composition of
blood (water, salts, acids, bases).
• Produce-
• Renin – regulates BP/ kidney function
• Erythropoeitin – stimulates RBC production from
marrow.
• Metabolism of Vitamin D to active form ( by PCT).

7. Components of urinary system
• Two Kidneys
– Perform all functions except actual excretion.
• Two Ureters
– Convey urine from Kidneys to Urinary Bladder
• Urinary Bladder
– Holds Urine until excretion
• Urethra
– Conveys urine from bladder to outside of body

8. kidneys/ key features
• A pair of bean shaped organs located against
posterior abdominal wall retro-peritoneally.
• Each kidney presents 2 surfaces, 2 ends and 2
borders.
• Long axis of kidney is directed downward and
laterally so upper end is nearer to the midline.
• Extend from T12 to L3

9. kidneys/ key features
• Left kidney is nearer to midline and to
diaphragm than the right one.
• Medial border presents a concavity called as
hilum.
• Transpyloric plane passes through the upper
part of right hilum and lower part of left hilum

10. Position of kidneys

12. Anterior relation

13. Posterior relation

15. Posterior relationship
Ribs-11and 12 for left and 12th for right
Muscles- 3 muscle
Nerves- 3 nerves
Diaphragm
Remember

16. Renal angle
• Angle between the lower border of the 12th
rib and lateral border of erector spinae.
• It overlies the lower part of kidney.
• Tenderness can be felt in this area in case of
perinephric abscess.

17. Covering of the kidneys
• Fibrous capsule ( true capsule)
• Perinephric fat
• Renal fascia( fascia of Gerota)
• Paranephric fat

18. Covering of the kidneys
• Fibrous capsule formed by condensation of
fibrous stroma of the kidney.
• In nephropexy, fibrous capsule is divided and
sutured with the posterior abdominal wall.
• Perinephric fat is abundant along the border
of kidneys, in lower pole and in the renal
sinus.
• Renal fascia is made up of condensation of
extra-peritoneal connective tissue.

19. Renal Fascia or fascia of Gerota
• Consists of two layers
1. Anterior layer or fascia of Toldt
2. Posterior layer of Fascia of Zuckerkendl
• Laterally both layer fused and continued with
the fascia transversalis
• Medially , anterior layer is continuous with
the similar layer of the opposite side in front
of the aorta and IVC.

21. Coverings of kidney
• Medially posterior layer covers the back of
kidney and renal vessels and blends with the
psoas fascia.
• Above , both layer fuse and re-split to cover
suprarenal gland. At the upper end of the
gland two layers fuse and continuous with the
subdiaphrgmatic fascia forming the
suspensory ligaments of suprarenal gland.

22. Coverings of kidneys
• Below, two layer do not fuse , extend
downward along the ureter and are finally lost
in extra-peritoneal connective tissue of iliac
fossa.
• Paranephric fat is located in between the
renal fascia and anterior layer of thoraco-
lumbar fascia.

23. Macroscopic structure

24. Macroscopic structure
• When splited longitudinally it presents 2 parts
Kidney proper – it is made up of outer cortex
and inner medulla.
• Cortex lies in between renal capsule and renal
pyramid ( cortical arch), and extends in
between pyramid as renal column.
• Medulla is made up of renal pyramid.
Renal sinus

27. Microscopic structure
• The urineferous tubules are the microscopic
structures of the kidneys. It is made up of
nephrons and collecting tubules.
• Nephron is the functional unit of the kidney,
responsible for the actual purification and
filtration of the blood.
• About one million nephrons in each kidney.
• Two types of nephrons
Cortical – 85%- responsible for Na resorption
Juxtramedullary – 15%- for water resorption

28. • The main differences in the two types of
nephrons are-
1. the length to which the loop of Henle extends
into the kidney.
2. Position of renal corpuscle
3. Functions
Parts of the Nephrons-
Renal corpscle = Bowman capsule + Glomerulus
PCT
Loop of Henle
DCT

29. Microscopic structure

31. 3 phases of urine formation

32. Renal Corpuscle(Malphigian body)
(Glomerular plexus + Bowman’s capsule)

33. Visceral layer of renal corpuscle

34. Filtration membrane

35. Filtration

36. Nephrotic syndrome
Protinuria; hypoalbuminemia and edema

37. PCT
• At the urinary pole of a renal corpuscle, the simple
squamous epithelium of the parietal layer of
Bowman's capsule undergoes an abrupt change to
become the tall cuboidal epithelium with microvilli (
brush border appearance)of the proximal tubule.

38. Loop of Henle
• It has descending and ascending limbs , each
having thick and thin part.
• Thin part makes a hair-pin bend in the deeper
plane of medulla .
• Due to the close association of two limb,
opposite flow of filtrate and variable
permeability to the water is responsible for
the counter-current multiplier mechanism.

39. Counter-current system

40. DCT
• Distal tubule cells possess their own type of Na+
transporter protein called the amiloride-sensitive
epithelial Na+ channel (ENaC). Aldosterone, can
increase the abundance of ENaC channels at the
cell surface, thereby stimulating Na+
reabsorption.
• Part of the DCT that comes in contact with the
afferent arteriole of glomerulus specialized for
sppecial function .this special portion is called as
macula densa.
• Epithelial lining is simple cuboidal.

41. Juxtra-glomerular apparatus

42. Function of juxtra-glomerular apparatus

43. Collecting tubules
• Collecting tubules are composed of a simple cuboidal
epithelium containing two distinct cell types: principal
(light) cells and intercalated (dark) cells.
• Principal cells of collecting tubules possess receptors for
ADH on their plasma membranes.
• Intercalated cells adjust urinary pH by secreting either H+
ions or bicarbonate ions. These cells are also noteworthy
because they synthesize a peptide called atrial natriuretic
peptide (ANP) , responsible for relaxation of afferent
arteriole and less reabsorption of sodium by collecting
tubules.
• These tubules join to form – duct of Bellini , which is
received by the minor calyces at the apex of renal pyramid.

45. Renal vasculature
Renal arteries arises at the level of L1- L2

46. Renal Vein Entrapment Syndrome
“nutcracker syndrome”
• In crossing the midline to reach the IVC, the longer left
renal vein traverses an acute angle between the SMA
anteriorly and the abdominal aorta posteriorly.
Downward traction on the SMA may compress
• The syndrome may include hematuria or proteinuria,
abdominal pain, nausea and vomiting (indicating
compression of the duodenum), and left testicular pain
in men (related to the left testicular vein draining into
the left renal vein proximal to the compression).

47. Brodel’s Line
Segmentation of kidneys

48. Branching generations after segmental artery
Lobar artery
Interlobar artery
Arcuate artery
Interlobular artery

50. Function?

51. Development

54. Ureter
• These are pair of muscular tubes( 25 cm) that are
continuous superiorly with the renal
pelvis, which is a funnel-shaped structure in the
renal sinus.
• Consists of three parts- renal pelvis, abdominal
part and pelvic part.
• Descend retroperitonealy and cross pelvic brim
• Enter posterolateral corners of bladder
• Run medially within posterior bladder wall before
opening into interior
• This oblique entry helps prevent backflow of
urine

57. Important relationship of Ureters :
They run Inferior to the ductus deferens in males
and inferior to the uterine artery in females.

58. Ureteric constrictions
At three points along their course the ureters
are constricted.
• the first point is at the ureteropelvic junction,
just inferior to the kidney.
• the second point is where the ureters cross
the common iliac vessels at the pelvic brim.
• the third point is where the ureters enter the
wall of the bladder. It is the narrowest one.

60. Ureter
• arteries supplying the ureters
divide into ascending and
descending branches, which form
longitudinal anastomoses.
Lymphatic drainage
• Upper part- lumbar node
• Middle part- common iliac nodes
• Lower part- ext. and internal iliac
nodes
• Nerve supply- T10 to L1/ S2-S4

61. Histology
• Innermost mucus membrane
- transitional epithelium
• Middle layer of smooth muscle
-inner longitudinal and outer circular layer.
– In lower part additional outer longitudinal layer
present.
• Outer layer is tunica adventitia- made up of
connective tissue.

63. Referred pain of ureteric colic
• Excessive distension or spasm of muscle caused by a
stone (calculus) provokes severe pain (ureteric colic),
particularly if the obstruction is gradually forced
down the ureter.
• It is referred to cutaneous areas innervated from
spinal segments which supply the ureter and shoots
down and forwards from the loin to the groin.
• it may extend into the proximal anterior aspect of
the thigh by projection to the genitofemoral nerve
(L1, 2).
• The cremaster, which has the same innervation, may
reflexly retract the testis.

64. Urinary Bladder
• The bladder is the most anterior element of
the pelvic viscera. Although it is entirely
situated in the pelvic cavity when empty, it
expands superiorly into the abdomen when
full.
• An empty bladder is somewhat tetrahedral
and has a base (fundus), neck, apex, a
superior and two inferolateral surfaces..

65. Parts of bladder- Male

66. Parts of bladder- Female

67. Base of Bladder in male

68. Base of Bladder- female

69. Neck of Urinary Bladder
• The neck of the bladder surrounds the origin
of the urethra.
• The neck is the most inferior and also the
most 'fixed' part of the bladder. It is anchored
into position by a pair of tough fibromuscular
bands
– pubovesical ligaments in female and
puboprostatic ligaments in male.

71. Interior of bladder

72. Interior of bladder and trigone

73. Space of Retzius

74. Ligaments of Bladder
•Lateral true ligaments
•Lateral Pubo-prostatic ligaments
•Medial Pubo-prostatic ligaments
( pubo-vesical ligaments in female)
•Median umbilical ligaments
•Posterior ligaments of bladder
Median umbilical fold
Medial umbilical fold
Lateral false ligaments
Posterior false ligaments

76. Histology of urinary bladder

77. • Arterial supply- superior and inferior vesical
artery( B/O internal iliac artery)
Uterine and vaginal artery instead of inferior vesical
artery in female.
• Venous drainage- vesical venous plexus on
inferolateral surfaces of bladder.
• Lymphatics- external iliac and lateral aortic
• Nerve supply- T11-L2/S2-S4

79. • Micturation is a reflex action involving sensory
and motor pathway mediated by lower
micturation center( spinal cord S2-S4).

80. These are really important!!!
• Neurogenic bladder- bladder disorders due to
nerve damage.
• Automatic or reflex bladder-due to
transection of cord above the lower
micturation center(S2-S4).
• Voluntary control is lost but reflex is intact.
• Autonomous bladder- destruction of lower
micturation center(S2-S4).
• Both voluntary and reflex control is lost

81. Development
• Mucosa of Trigone – mesonephric duct(
mesoderm)
• Remaining mucosa- vesicouretharal part of
cloaca ( endoderm).
• Apex – allantoic diverticulum
• Musculature part- Splanchnic layer of lateral
plate mesoderm which surrounds the cloaca.

82. Urethra
• The male urethra is a muscular tube
approximately 20 cm in length. The urethra in
men extends from the neck of the bladder(
preprostatic urethra) through the prostate gland
(prostatic urethra) to the urogenital diaphragm of
the perineum (membranous urethra), and then
to the external opening of the glans (penile or
spongy urethra).
• The female urethra is approximately 4 cm in
length and extends from the neck of the bladder
to the external urethral orifice of the vulva

84. Visit – www.slideshare.comfor this slide and for similar slides

85. Test yourself
• Where is the micturation center in the brain??- pons
• Which of the following is found exclusively in the renal medulla?
a.Proximal convoluted tubules b. Distal convoluted tubules
c. Collecting ducts d. Thin loops of Henle
• Space for enlargement of bladder is ………….
a. Space of Reitzius b. Verumontanum
c. Urogenital raphe d. Pelvic space
• In kidney the less vascular area separating anterior and posterior
segment is known
as………….
a. Brodie’s line b. Canton’s line
c. Calot’s line d. Seshachalam’s line

86. T/F
• life expectancy of individual with a single kidney is the same
as those with two kidneys.
• Most common position of ectopic kidney is hypogastric region
of abdomen.( it is pelvis)
• Widest and most dilated part of urethra is………….
a. Membranous b. Prostatic
c. Penile d. External meatus