The urinary system comprises the kidneys, ureters, bladder, and urethra. The kidneys filter waste and fluid from the blood to produce urine. The ureters carry urine from the kidneys to the bladder. The bladder stores urine until voiding. The urethra then carries urine from the bladder out of the body. Together these structures precisely regulate fluid and electrolyte balance and remove wastes.

3. Anatomic and Physiologic Overview
The urinary system comprises the
kidneys, ureters, bladder, and
urethra.
A thorough understanding of the
urinary system is necessary
for assessing individuals with acute
or chronic urinary dysfunction
and implementing appropriate
nursing care.

4. Anatomy of the Upper
and Lower Urinary Tracts
The urinary system—the structures of
which precisely maintain
the internal chemical environment of the
body—perform various
excretory, regulatory, and secretory
functions.

5. Kidneys
The kidneys are a pair of
brownish-red structures located
retroperitoneally (behind and
outside the peritoneal cavity) on
the posterior wall of the
abdomen from the 12th thoracic
vertebra to the 3rd lumbar
vertebra in the adult

6. Kidneys
• An adult kidney weighs 120 to
170 g (about 4.5 oz) and is 12
(about 4.5 inches) long, 6 cm
wide, and 2.5 cm thick.
•The kidneys are well protected
by the ribs, muscles, Gerota’s
fascia, perirenal fat, and the
renal capsule, which surround
each kidney.

7. Kidneys
The kidney consists of
two distinct regions:
Renal Parenchyma
Renal Pelvis

8. Kidneys
Renal Parenchyma
The renal parenchyma is divided into
the cortex and the medulla.
The cortex contains the
glomeruli, proximal and
distal tubules, and
cortical collecting ducts
and their adjacent
peritubular capillaries.
The medulla resembles
conical pyramids. The
pyramids are situated
with the base facing the
concave surface of the
kidney and the apex
facing the hilum, or
pelvis

9. Kidneys
Renal Pelvis
The hilum, or pelvis, is the concave
portion of the kidney through which
the renal artery enters and the renal
vein exits. The renal artery (arising
from the abdominal aorta) divides into
smaller and smaller vessels,
eventually forming the afferent
arteriole.

10. Kidneys
Renal Pelvis
The afferent arteriole branches to
form the glomerulus, which is the
capillary bed responsible for
glomerular filtration. Blood leaves the
glomerulus through the efferent
arteriole and flows back to the inferior
vena cava through a network of
capillaries and veins.

13. Kidneys
Each kidney contains about 1
million nephrons, the functional
units of the kidney. Each kidney is
capable of providing adequate
renal function if the opposite
kidney is damaged or becomes
nonfunctional.
Nephrons

14. Kidneys
• The nephron consists of a glomerulus
containing afferent and efferent
arterioles, Bowman’s capsule, proximal
tubule, loop of Henle, distal tubule, and
collecting ducts.
• Collecting ducts converge into papillae,
which empty into the minor calices, which
drain into three major calices that open
directly into the renal pelvis.
Nephrons

15. Kidneys

16. Nephrons are struturally divided
into two types: cortical and
juxtamedullary.

17. Kidneys
The glomerular membrane normally allows
filtration of fluid and small molecules yet
limits passage of larger molecules, such as
blood cells and albumin. Kidney function
begins to decrease at a rate of
approximately 1% each year beginning at
approximately age 30.

18. The glomerulus is
composed of three filtering
layers: the capillary
endothelium, the basement
membrane, and the
epithelium.

20. Kidneys
• Urine formation
• Excretion of waste products
• Regulation of electrolytes
• Regulation of acid–base balance
• Control of water balance
• Control of blood pressure
• Renal clearance
• Regulation of red blood cell production
• Synthesis of vitamin D to active form
• Secretion of prostaglandins

21. Ureters
Urine, which is formed within the
nephrons, flows into the ureter, a
long fibromuscular tube that
connects each kidney to the bladder.
The ureters are narrow, muscular
tubes, each 24 to 30 cm long, that
originate at the lower portion of the
renal pelvis and terminate in the
trigone of the bladder wall.

22. Ureters
There are three narrowed areas
of each ureter:
ureteropelvic junction
ureteral segment
ureterovesical junction

23. Ureters
ureterovesical junction
The angling of the ureterovesical
junction is the primary means of
providing antegrade, or downward,
movement of urine, also referred to as
efflux of urine.
This angling prevents vesicoureteral
reflux, which is the retrograde, or
backward, movement of urine
from the bladder, up the ureter, toward
the kidney.

24. Ureters
ureterovesical junction
The angling of the ureterovesical
junction is the primary means of
providing antegrade, or downward,
movement of urine, also referred to as
efflux of urine.
This angling prevents vesicoureteral
reflux, which is the retrograde, or
backward, movement of urine
from the bladder, up the ureter, toward
the kidney.

25. During voiding (micturition),
increased intravesical pressure keeps
the ureterovesical junction closed and
keeps urine within the ureters. As
soon as micturition is completed,
intravesical pressure returns to its
normal low baseline value, allowing
efflux of urine to resume.
Therefore, the only time that the
bladder is completely empty is in the
last seconds of micturition before
efflux of urine resumes.

26. Ureters
ureterovesical junction
The angling of the ureterovesical
junction is the primary means of
providing antegrade, or downward,
movement of urine, also referred to as
efflux of urine.
This angling prevents vesicoureteral
reflux, which is the retrograde, or
backward, movement of urine
from the bladder, up the ureter, toward
the kidney.

27. “The left ureter is slightly
shorter than the right”
Did
YOU
know?

28. Ureters
The lining of the ureters is made up of
transitional cell epithelium called
urothelium. As in the bladder, the
urothelium prevents reabsorption of urine.
The movement of urine from the renal
pelves through the ureters into the bladder
is facilitated by peristaltic waves (occurring
about one to five times per minute) from
contraction of the smooth muscle in the
ureter wall (Walsh, Retik, Vaughan & Wein,
1998).

29. Ureters
Ureters functions as
tubes that actively
convey urine from the
kidneys to the bladder.

30. Bladder
The urinary bladder is a
muscular, hollow sac located just
behind the pubic bone.
The bladder is characterized
by its central, hollow area called
the vesicle, which has two inlets
(the ureters) and one outlet (the
urethrovesical junction), which
is surrounded by the bladder
neck.

31. Bladder
Adult bladder capacity is
about 300 to 600 mL of
urine. In infancy, the
bladder is found within the
abdomen. In adolescence
and through adulthood, the
bladder assumes its
position in the true pelvis.

32. Bladder
The wall of the bladder comprises
four layers:
adventitia
detrusor
lamina propria
urothelium

33. Bladder
urothelium
The urothelium layer is specialized,
transitional cell epithelium, containing a
membrane that is impermeable to
water.
The urothelium prevents the
reabsorption of urine stored in the
bladder

34. Bladder
The bladder neck contains bundles of
involuntary smooth muscle that form a portion
of the urethral sphincter known as the internal
sphincter.
The portion of the sphincteric mechanism that
is under voluntary control is the external urinary
sphincter at the anterior urethra, the segment
most distal from the bladder (Walsh et al., 1998).

35. Bladder
The urinary bladder functions as a muscular
sac that expands as urine is produced by the
kidneys to allow storage of urine until voiding is
convenient.

36. Urethra
The urethra arises from the base
of the bladder: In the male, it
passes through the penis; in the
female, it opens just anterior to
the vagina.
In the male, the prostate gland,
which lies just below the bladder
neck, surrounds the urethra
posteriorly and laterally.

37. Urethra
The urethra is a muscular tube
that drains urine from the body; it
is 3–4 cm long in females, but
closer to 20 cm in males.

38. Thank
you.