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The Urinary System
Dept. of Anatomy
Luzhou Medical College
Edited by professor Xiao
The Urinary System
Kidneys, ureters,
urinary bladder &
urethra
Urine flows from each
kidney, down its
ureter to the bladder
and to the outside via
the urethra
Filter the blood and
return most of water
and solutes to the
bloodstream and
excrete the waste
products.
Solution 溶解
Kidney
Location
The kidneys lie on the posterior abdominal all on
either side of the vertebral column. The distance
between the inferior extremities is wider than that
between the superior extremities.
The right kidney is lower than the left one because
of the large size of the lobe of the live. The
superior extremity of the left kidney is at the level
of the inferior border of the body of the 11th
thoracic vertebra, the inferior extremity of the left
kidney is at the level with the inferior border of the
body of the 2nd lumbar vertebra.
The superior extremity of the right kidney is at the level with the
superior border of the body of the 12th thoracic vertebra, and the
inferior extremity is at the level with the superior border of the body
of the third lumbar vertebra. The renal hilum is at the level of the
first lumbar vertebra, 5cm
lateral to the midline of
the body. The area
between the 12th rib and
the lateral border of the
erector spinae is called
the renal region in
clinic. The location of
The kidneys varies in
different cases. General
in female it is lower
than in man.
Location of the kidney
renal region
External Anatomy of Kidney
2 surfaces
anterior: convex
posterior: plane
2 borders
medial: renal hilum
lateral: convex
renal sinus and renal
pedicle
2 poles :
superior: broad & thin
inferior: narrow &
thick
The hilum transmits the
renal vessels, nerves and the
part of the pelvis. The renal
hilum leads into a central
recess named the renal
sinus.
The renal sinus is filled with
the branches of the renal
artery and vein, nerves,
lymphatic vessels, minor
renal calices, major renal
calices, renal pelvis and
adipose tissue.
Renal pedicle
The structures which pass through the renal hilum are
enclosed together by connective tissue.
Internal structures
Cortex
Renal columns
It is composed of the renal
glomeruli and renal tubules
Medulla
Renal pyramids(base and apices)
2 or 3
(7 to 12 in each kideney)Renal papilla
(Papillary foramina10to 30 in each papillae) 2 or 3
Minor renal calices
Renal pelvis
Major renal calices
Coverings
Fibrous capsule
Fatty renal capsule
Renal fascia
Adipose
capsule
Renal
fascia
Anterior layer
Fibrous
capsule
Posterior layer
Blood vessels & ureter enter hilum of kidney
Renal capsule : from outer to inner is the renal fascia, adipose
capsule and the fibrous capsule.
Adipose capsule that helps protect from trauma
Renal fascia = dense, irregular connective tissue that holds
against back body wall
Internal Anatomy of Kidney
What is the difference between renal hilum & renal sinus?
Outline a major calyx & the border between cortex &
medulla.
Renal
segments
•①Superior
segment
•②Superior
anterior segment
③inferior
Renal segments
segment
•④Inferior
anterior segment
⑤Posterior
segment
Cast of
kidney
Blood & Nerve Supply of Kidney
Abundantly supplied with blood vessels
 receive 25% of resting cardiac output via renal arteries
Functions of different capillary beds
 glomerular capillaries where filtration of blood occurs
 vasoconstriction & vasodilation of afferent & efferent
arterioles produce large changes in renal filtration
 peritubular capillaries that carry away reabsorbed
substances from filtration.
 vasa recta supplies nutrients to medulla without disrupting
its osmolarity form
Sympathetic vasomotor nerves regulate blood flow & renal
resistance by altering arterioles
Glomerulus 球 osmolarity 渗透性
Overview of Kidney
Functions
Regulation of blood ionic composition
 Na+, K+, Ca+2, Cl- and phosphate ions
Regulation of blood pH, osmolarity & glucose
Regulation of blood volume
 conserving or eliminating water
Regulation of blood pressure
 secreting the enzyme renin ( 血管紧张肽）
 adjusting renal resistance
Release of erythropoietin（红细胞生成素） & calcitriol（降钙素）
Excretion of wastes & foreign substances
Na+ sodium ions K+ potassium ions Ca+2 calcium ions Clchlorine ions
The renal anomalies
①The early pelvic position of the kidneys may
persists.
②the kidneys are connected by a transverse
bridge of renal tissue forming the “horseshoe
kidney”.
③the kidney of one side may be congenital
absence or imperfect development.
④teo kidneys may be occur on the same side.
⑤single or multiple congenital renal cysts
may also be present.
Renal
cysts
horseshoe
Variation
Pelvic
position
Diuretics
Substances that slow renal reabsorption
of water & cause diuresis (increased
urine flow rate)
caffeine which inhibits Na+ reabsorption
 alcohol which inhibits secretion of ADH)



Diuresis (利尿） Na+ sodium ions
Caffeine （咖啡因） ADH antidiuretic hormone
Ureters
It is muscular tube, about 20 to
30 cm in length.
Varies in diameter from 1-10
mm.
Extends from renal pelvis to
bladder.
Retroperitoneal
Enters posterior wall of
bladder ( intramural seg.)
Physiological valve only


bladder wall compresses
arterial opening as it expands
during filling
flow results from peristalsis,
gravity & hydrostatic pressure
Trigone
Ureters
Three parts
The abdominal part
It is continuous with the pelvis superiorly,
at the superior pelvic aperture, the left
ureter crosses through the terminal part
of the left common iliac artery anteriorly,
and the right ureter passes the
beginning of the right external iliac
artery anteriorly, to continue with the
pelvic part.
Ureters
The pelvic part
It passes downwords along the lateral wall of
the lesser pelvis, then turns medially at the
level of ischial spine to the base of the urinary
bladder. At here the ductus deferens crosses
it anteriorly to its medial sode in the male. In
the femal the pelvic part of the ureter turns
downwords, forwords and medially. At the
level of ischial spine, 2cm lateral to the cervix
of uterus, it is crosses anteriorly by the
uterine vessels. It then runs along the lateral
side and the anterior surface of the vagina to
the base of the urinary bladder.
Ureters
The intramural part
It passes obliquely through the wall of
the urinary bladder for 1.5cm long,
before opening into the superolateral
angle of fundus of bladder. Where the
bladder is filled up, the intramural part
seces as a valve to prevent the
backflow of urine.
Ureters
Three constrited parts
The ureters are not uniform in calibre. Three
constricted parts are the places where the
renal stones stay usually.
①at the junction of the ureter and the renal
pelvis.
②at the point where ureter crosses the iliac
vessels.
③intramural part.
These constricted areas are potential sites of
obstruction by ureteric stones.
Urinary Bladder
Hollow, distensible muscular organ with capacity of 700 - 800 milliliter.
Trigone is smooth flat area bordered by 2 ureteral openings and one urethral opening
Internal structures of the bladder and urethra
Apex
Body
Fundus
Neck
External features
Location of urinary bladder
In the adult the empty bladder is entirely within the
lesser pelvis, but as it becomes distended it
upwards and forwards into the abdominal cavity. At
the baby, the empty bladder is spindle-shaped , and
lies at a relatively higher level than in the adult.
It is a interperitoneal organ, only the superior
surface and upper portion of the inferolateral
surface are covered by peritoneum, which is
reflected from the lateral wall of the pelvis and from
the anterior abdominal wall just above the level of
the pubic symphysis when the bladder is empty.
As the bladder is filled by urine, the superior
surface of the bladder enlarges and bulges
upward into the abdominal cavity, the peritoneal
covering is peeled off away from the lower part
of the anterior abdominal wall, and reflection of
the peritoneum becomes higher. So that the
bladder contracts directly with the anterior
abdominal wall. Therefore the puncture of
bladder can be performed just above the pubic
symphysis within injuring the peritoneum.
location
The urethra
The urethra extends from internal
urethral orifice of the urinary bladder to
the external urethral orifice. It is very
different in male and femal.
The male urethra serves a common
tube for urinary and genital systems. It
may be divided into three parts. It will be
described in the genital system in detail.
The femal urethra
The femal uretha
It is membranous canal, about 5cm long, extending from the
bladder to external urethral orifice in the vaginal vestibule. Its
diameter is about 6mm. It is dorsal to the pubic symphysis and
ventral to the anterior wall of the vagina. Its direction is obliquely
and forward and slightly curved. It perorates the pelvic floor and
uroginital diaphragm, and its external orifice is situated just
anterior to the vaginal orifice and about 2.5cm posteroinferior to
the glans of clitoris. Where the urethra passes through the
uroginital diaphragm, the striated muscle of uroginital diaphragm
forms the urethrovaginal sphincter. Many small urethral
glands open into the urethra. The largest of these is the
paraurethral glands, the duct of which open into the vaginal
vsetibule on either side of the external orifice of urethra.
The renal
transplantation
The kidney can be removed from the donor
without damaging the suprarenal gland
because of the weak septum of renal fascia
that separates the kidney from this gland.
Renal transplantation is now an established
operation for the treatment of selected cases
of chronic renal failure. The site artery and
vein are joined to the external iliac artery and
vein, respectively, and the ureter is sutured
into the urinary bladder.