The document provides an overview of the anatomy and functions of the urinary system. It describes the major components including the kidneys, ureters, urinary bladder, and urethra. The kidneys filter waste from the blood and produce urine, which travels through the ureters to the bladder. The bladder stores urine until urination, when it is expelled through the urethra. Key structures like the nephrons and vasculature are also summarized.

1. 1
Urinary organs

2. Outline
 Introduction
 Kidney
 Ureter
 Urinary bladder
 Urethra
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3. Objectives
At end of this session students able to know:
 Describe the external and internal gross anatomical features of
the kidneys
 Outline the path of blood flow through the kidneys
 Describe the structure of renal corpuscles and renal tubules
 Describe the anatomy of the ureters, urinary bladder, and
urethra.
 Understand the innervation and vasculature of the urinary
organs
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4. Introduction
 Urinary system consists of :
– Two kidneys
– Two ureters
– One urinary bladder
– One urethra
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5. Functions of urinary system
 Filtrations of blood, allowing
toxins, metabolic wastes, and
excess ions to leave the body
in urine.
 Regulate volume and chemical
makeup of the blood.
 Maintain the proper balance
between water and salts, and
acids and bases.
 Production hormones-
calcitriol and erythropoietin.
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6. Kidneys
 Paired kidneys are reddish and
bean–shaped organs
 Located just above the waist
between the peritoneum and the
posterior wall of the abdomen
(called retroperitoneal organ).
 Kidneys are located between the
levels of the last thoracic and
third lumbar vertebrae (T12- L3).
 They are partially protected by
ribs 11 and 12.
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7. 7

8. External Anatomy of the Kidneys
A typical adult kidney is :
– 10–12 cm long
– 5–7 cm wide
– 3 cm thick
– Has a mass of 135–150 g
 Right kidney is slightly
lower than the left .
– Because the liver occupies
considerable space on the
right side superior to the
kidney
Anterior view of urinary system
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9. Structure of the kidney
Each kidney has:
 Anterior and posterior
surface
 Medial borders (concave)
 Lateral borders (convex)
 Superior and inferior
poles.
 On the medial side of each
kidney is a small area called
the hilum.
 Ureters, renal blood vessels,
lymphatics, and nerves enter
and exit at the hilum.
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10. Kidneys
 The concave medial border of each kidney faces the vertebral
column
 Near the center of the concave border is an indentation called the
renal hilum
 Through which the ureter emerges from the kidney along with
blood vessels, lymphatic vessels, and nerves.
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11. Three layers of tissue surround each kidney
 From deep to superficial
– Renal capsule
– Adipose capsule
– Renal fascia
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12. 12
1. Renal capsule
– Deep layer
– It is a smooth, transparent sheet of dense irregular connective tissue
that is continuous with the outer coat of the ureter.
– It serves as a barrier against trauma and helps maintain the shape of
the kidney.
– Inner layer of fibrous capsule that prevents kidney infection.
2. Adipose capsule
– Middle layer
– Fatty mass that cushions the kidney and helps attach it to the body
wall
– It also protects the kidney from trauma and holds it firmly in place
within the abdominal cavity.
3. Renal fascia
– Outer layer of dense fibrous connective tissue.
– That anchors the kidney to the surrounding structures and to the
abdominal wall.

13. Internal Anatomy of Kidneys
 Kidney is divided into two parts
1. An outer renal cortex:
superficial, light red region
2. An inner medulla: a deep,
darker reddish-brown inner
region
 Medulla- consists of a number
of cone shaped renal pyramids.
 The base of each pyramid is
located at the boundary b/n the
cortex & the medulla.
 Renal papillae- are tips of the
pyramids that projects into the
renal sinus. 13

14.  Renal cortex is the
smooth-textured area.
 Extending from the renal
capsule to the bases of the
renal pyramids and into
the spaces between them.
 Extensions of the cortex
called renal columns
project b/n the pyramids.
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Internal Anatomy of Kidneys

15. Microscopic Structure of the kidney
NEPHRON
 Nephron is the structural and
functional unit of the kidney.
 Each kidney contains
approximately 1 million
nephrons.
 Filtrate (filtered fluid) formed
by the nephrons drains into
large papillary ducts.
– Which extend through the
renal papillae of the pyramids.
 The papillary ducts drain into
cuplike structures called minor
and major calyces.
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16. Internal Anatomy…
 Minor calyces- are funnel
shaped structure that
surround the renal papillae.
 Major calyces- larger
funnels formed from the
joining together of minor
calyces.
 There are 8-20 minor
calyces & 2 or 3 major
calyces per kidney.
 Renal pelvis- a single large
cavity that delivers urine from
major calyx to a small tube the
ureters. 16

17. 17

18. 18
Renal tubules
Nephrons consists of :-
- Bowman’s capsule
- A proximal convoluted tubule
- A loop of Henle
- A distal convoluted tube
- Collecting duct w/c carrier the urine from the cortex to the
calyces
 The bowman’s capsule & both convoluted tubules are in the renal
cortex.
 The collecting tubules & part of the loops of Henle enter the renal
medulla → Renal papilla → Minor calyx → Major calyx →
Renal pelvis  Ureter

19. 19
Internal anatomy of the kidneys

20. Blood and Nerve Supply of the Kidneys
 Although the kidneys constitute less than 0.5% of total body
mass.
 They receive 20–25% of the resting cardiac output via the
right and left renal arteries.
 In adults, renal blood flow, the blood flow through both
kidneys, is about 1200 mL per minute.
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21. Vasculature of kidney
 Renal artery: supplies each kidney.
 Right renal artery is longer and passes posterior to the
inferior vena cava.
 Accessory renal arteries or extrahilar arteries are common.
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22. Renal blood vessels
 Arterial blood enters the kidney through the renal artery-
Segmental arteries - interlobar arteries -the actuate arteries
–interlobular arteries-afferent arterioles.
 Deliver blood into glomeruli capillary w/c produce a blood
filtrate that enters the urinary tubules.
Veins drainage
 Efferent arterioles – peritubular capillaries – interlobular
veins – arcuate veins – interlobar veins - renal veins –
inferior vena cava.
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23. 23

24. 24
Blood supply of the kidneys

25. Ureters
 Ureters - a muscular tubular
organ 25cm long each
 The renal pelvis becomes
continuous with the ureter at
the uretero pelvic junction.
 Extends from the renal pelvis
to the bladder.
 Conduct urine to the urinary
bladder.
 It is retroperitoneal organ. 25

26. Ureters
 Each of the two ureters transports
urine from the renal pelvis of one
kidney to the urinary bladder.
 Peristaltic contractions of the
muscular walls of the ureters push
urine toward the urinary bladder.
 Hydrostatic pressure and gravity
also contribute.
 Transitional epithelium is able to
stretch a marked advantage for any
organ that must accommodate a
variable volume of fluid.
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27. Ureteric constriction
At three points along their course
the ureters are constricted:
I. At the uretero pelvic junction
II. Where the ureters cross the
common iliac vessels at the
pelvic brim
III. Where the ureters enter the
wall of the bladder.
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28. Vasculature of Ureters
 Arterial supply to the pelvic
parts of the ureters is variable.
– Common iliac, internal iliac,
and ovarian arteries.
 The most constant arteries
supplying the terminal parts of
the ureter in females are
branches of the uterine
arteries.
 Venous drainage from the
pelvic parts of the ureters
generally parallels the arterial
supply.
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29. Urinary tract stones (calculi)
 Occurrence of stone or calculi in ureter.
 Occur more frequently in men than in women.
 Most common in people aged between 20 and 60 years.
 The typical presentation is a patient with pain that radiates from
the loin region into the groin, and even into the scrotum or labia
majora.
 Blood in the urine (hematuria) may also be noticed.
 The complications of urinary tract stones include infection,
urinary obstruction, and renal failure.
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30. Urinary Bladder
 A hollow, distensible muscular
organ.
 Situated in the pelvic cavity
posterior to the pubic symphysis.
 It is characterized by its
distensibility.
 Bladder is a temporary reservoir
for urine and it contracts to
eliminate urine.
 Varies in size, shape, position, and
relationships according to its
content, and the state of
neighboring viscera.
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31. Position
 In adults:
– Empty bladder lies in pelvis
minor posterior and slightly
superior to pubic bones.
– When filled ascends to
pelvic major and abdomen.
 In infants: found in abdomen
– Enters pelvic major at about
6 years of age and pelvic
minor at puberty.
 In males, it is directly anterior
to the rectum.
 In females, it is anterior to the
vagina and inferior to the
uterus.
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Urinary Bladder…….

32.  Folds of the peritoneum hold
the urinary bladder in
position.
 When slightly distended due
to the accumulation of urine,
the urinary bladder is
spherical.
 When it is empty, it collapses.
 Urinary bladder capacity
averages 700–800 mL.
 Capacities in the adult male
vary from 120 – 320ml.
 Micturition usually occurring
at 280 mL
 When the bladder is filled it
contains about 500 mL 32
Urinary Bladder

33. Anatomy and Histology of the Urinary Bladder
 In the floor of the urinary bladder is a small triangular area called
trigone.
 The opening of the two ureters and the urethra mark a smooth
surface triangular area is called trigone on the bladder floor.
 The opening into the urethra, the internal urethral orifice, lies in
the anterior corner.
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34. Arterial supply
Branches of internal iliac arteries
 Superior vesical artery: supply anterosuperior parts
 Inferior vesical artery and Vaginal artery: supply fundus
(posterioinferior) in male and female, respectively
Venous drainage
 Correspond to arteries and drain into internal iliac vein.
Lymphatic drainage
 Superior part: to external iliac lymph nodes
 Inferior part: to internal iliac lymph nodes
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Vasculature of Bladder

35. CLINICAL CONNECTION | Urinary Incontinence
 A lack of voluntary control over micturition is called urinary
incontinence.
 In infants and children under 2–3 years old, incontinence is
normal because neurons to the external urethral sphincter muscle
are not completely developed.
 Voiding occurs whenever the urinary bladder is sufficiently
distended to stimulate the micturition reflex.
 Urinary incontinence also occurs in adults.
 There are four types of urinary incontinence—
– Stress
– Urge
– Overflow
– Functional
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36. Urethra
 Tubular, conveys urine from
urinary bladder to outside.
 Its wall contains mucus
secreting urethral glands.
 Tube extend from internal
urethral orifice to exterior.
 Passage way for discharging
urine (and semen in male).
 Consists of two muscular
sphincters:
– Internal urethral sphincter –
formed from the detrusor
muscle of bladder (smooth
muscle)
– External urethral sphincter –
voluntary skeletal muscle. 36

37. Females urethra
 The urethra lies directly posterior to the pubic symphysis.
 4cm long, empties urine through urethral orifice into the
vestibule b/n the labia minora.
 Positioned immediately anterior to the vaginal orifice, and 2.5cm
posterior to the clitoris.
 Opening of the urethra to the exterior, external urethral orifice
– Located between the clitoris and the vaginal opening
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38. Male Urethra
 It is about 18-20 cm long.
 Extends from the internal urethral orifice in the bladder to the
external meatus.
 Located at the tip of the glans penis in males.
 Serves both as urinary and reproductive systems
 Conveys urine from urinary bladder to the exterior.
 Also provides an exit for semen (sperm + seminal fluid).
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39. 39
Parts of Male Urethra
 S-shaped because of the shape of penis.

40. Parts of Male Urethra
Has three parts:
1. Prostatic Part-
– Descends through the prostate
gland.
– Varies in diameter and length.
– Depending on whether the
bladder is filling.
– This is 3-4 cm long
– The widest & most dilatable
part of the urethra
– Receives drainage from bladder,
prostate, and ejaculatory ducts.
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41. Parts of Male Urethra
2. Membranous Part
 It is the shortest part (1-2cm) and least dilatable part.
 Thinnest and narrowest (except external urethral orifice) .
 Posterolateral to it on each side is bulbourethral gland and duct.
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42. Parts of Male Urethra
3. Spongy part
 Is the part with in the penis.
 The longest part 10 to 16 cm long.
 Lies in the corpus spongiosum of penis.
 Extends from bulbs body to external urethral orifice.
 Expanded in bulb and in glans penis.
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43. 43
Comparison between male and female urethras

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