The urinary system consists of the kidneys, ureters, bladder, and urethra. The kidneys filter waste from the blood to produce urine. Urine travels from the kidneys down the ureters into the bladder, where it is stored until urination. During urination, urine exits the body through the urethra. The kidneys contain nephrons, which are the functional filtering units of the kidney and include a glomerulus and renal tubule. Nephrons remove waste from the blood via glomerular filtration and reabsorb useful molecules like water before urine is stored in the bladder.

1. Preseneted by:
Mr. vivek jamnik

2. URINARY STSTEM (Excretory
system)
 The urinary system comprises the
kidneys, ureters, bladder, and
 urethra.
 KIDNEY – regulate blood volume
and composition, regulate pH,
produce hormones and excrete
waste
 URETERS- transport urine from
kidney to urinary bladder
 URINARY BLADDER- store urine
and expels through urethra
 URETHRA- discharge urine from
the body

3. KIDNEY…..
The kidneys are a pair of
brownish-red structures
bean-shaped appearance,
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
 An adult kidney weighs 120
to 150 gm and is 12cm long,
6 cm wide, and 2.5 cm thick.
• The kidneys are well
protected by the ribs,
muscles, perirenal fat, and
the renal capsule, which
surround each kidney.

4. Position and relations
Left Right
Posterior  Diaphragm (postero-superiorly)
 Quadratus lumborum (postero-laterally)
 Psoas major postero-medially
 Transversus abdominis postero-laterally
 Subcostal nerve and vessels
 Iliohypogastric and ilioinguinal nerves descend diagonally across
posterior surface
Anterior Lies with pancreas and spleen in
the stomach bed
 Adrenal gland
 Stomach
 Spleen
 Pancreas (tail)
 Jejunum
 Descending colon
 Posterior wall of omental
bursa
 Peritoneum
 Superiorly related to
inferior surface of liver
 Descending part of
duodenum
 Right colic (hepatic)
flexure lies anterior to
lateral border and inferior
pole
 Small intestine (inferiorly)
 Peritoneum
Medial  L adrenal gland  Right adrenal gland –
wedged between superior
pole and IVC
 IVC

5. STRUCTURE….
 Each kidney is enclosed in a renal
capsule, which is surrounded by
adipose tissue.
 Internally, the kidneys consist of a
renal cortex, renal medulla,
renal pyramids, renal columns,
major and minor calyces, and a
renal pelvis.
 Blood enters the kidney through
the renal artery and leaves
through the renal vein.

6.  The kidney consists of two
distinct regions:
 Renal Parenchyma
 The renal parenchyma is
divided into
 the cortex and the medulla.
Renal Pelvis
Renal Parenchyma
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

7. CONTI…..
 The inner layer or Medulla is
comprised of Renal
Pyramids. The pyramids
contain: • Medullary
portions of Loops of Henle
• Medullary Portions of
Collecting Ducts
 Multiple pyramids taper and
join forming a minor calyx.
Several combined make a
major calyx.
 The major calyces join and
enter a funnel shaped renal
pelvis that directs urine into
the ureter.

8. Renal Pelvis
 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.
 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.

9.  Hilum
 At the concave part of each kidney
 Renal vein exits (anteriorly)
 Renal artery enters (posterior to renal vein)
 Renal pelvis exits (posterior to artery)
 Renal pelvis
 Funnel-shaped
 Lined with transitional epithelium with a smooth muscle
and connective tissue wall
 Continuous inferiorly with ureter
 Divides into major and minor calyces
 Urine  collecting tubule  minor calyx  major
calyx  renal pelvis  ureters  bladder

10.  Cortex
 Beneath capsule, extends towards the pelvis as
renal columns lying between pyramids of medulla
 Apices of several pyramids open together into a renal
papilla, each of which projects into a renal calyx

11. `
Arterial supply
 Renal arteries
 branches of aorta at L1/L2 lie behind pancreas and renal
veins
 Enter at hilum, giving rise to
 Anteriorly – apical, upper, middle and lower segments
 Posteriorly – posterior segment
Venous drainage
 Renal veins
 Communicate widely
 Drain into IVC
Lymphatic drainage
• Para-aortic nodes at L1/L2

12. 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 transport urine
from the renal pelves of the
right and left kidneys to the
urinary 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 bladder wall.
pass beneath the urinary
bladder, which results in the
bladder compressing the
ureters and hence preventing
back-flow of urine when
pressure in the bladder is high
during urination.

13.  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.
 “The left ureter is slightly shorter than the right”

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

15.  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.
ureterovesical junction

16. Bladder
The urinary bladder is a
muscular, hollow sac located just
behind the pubic bone.
The urinary bladder is posterior
to the pubic symphysis
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.

18. Toward the base of urinary
bladder, the ureter drains into the
urinary bladder via the ureteral
opening.
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.
The shape of urinary bladder
depends on how much urine is
contain. when empty, it look like a
deflated balloon.

19.  Capacity ~700-800 ml
 Smaller in female because, uterus occupies the
space superior to the urinary bladder
Bladder
The wall of the bladder comprises
four layers:
adventitia
detrusor
lamina propria
urothelium

20.  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
 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.
urothelium

21.  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.
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 both male and female, the urethra is the passageway for
discharging urine from the body.
 In the male, the prostate gland, which lies just below the
bladder neck, surrounds the urethra posteriorly and
laterally.
Urethra

22. The male urethra also serves as the duct through
which semen is ejaculated.
Maindifference between the urinary systemof male and female is the
“lengthof urethra.”

23. • 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

24. NEPHRONS
 The functional unit of the kidney is called the nephron
 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.
 Consist of 2 part: renal corpuscle, and renal tubule
 Renal corpuscle =
 glomerular (bowman’s capsule)
 glomerulus
 Renal tube
 Proximal convoluted tubules
 Nephron loop (descending & ascending)
 Distal convoluted tubules
 Collecting ducts converge into papillae, which empty into the
minor calices, which drain into major calices that open
directly into the renal pelvis.

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

26. FUNCTION OF NEPHRON
 Nephrons perform three basic tasks: glomerular
filtration, tubular reabsorption, and tubular secretion.
 Together, the glomerular endothelium form a leaky
filtration membrane that permits the passage of water and
solutes from the blood into the capsular space.
 Blood cells and most plasma proteins remain in the blood
because they are too large to pass through the filtration
membrane.
 The pressure that causes filtration is the blood pressure in
the glomerular capillaries.

28. Filtration
 Takes place through the semipermeable walls of the
glomerular capillaries
 almost impermeable to proteins and large molecule
 Glomerular filtrate is formed by squeezing fluid through
glomerular capillary bed
 Hydrostatic pressure (head of pressure) is controlled by
afferent and efferent arterioles, and provided by arterial
pressure
 About 20% of renal plasma flow is filtered each minute
(125 ml/min). This is the glomerular filtration rate
(GFR).
 Autoregulation

29. Tubular reabsorption
 60% of solute is
reabsorbed in
proximal tubule
 Different parts
of tubule system
optimised to
absorb different
components of urine
 Distal tubule and collecting duct determines final
urine concentration
 Regulated by ADH production by posterior pituitary

30. Hormones
 Renin
 Increases production of angiotensin II
 Aldosterone
 Stimulates water and sodium ion resorption in distal tubule
 Atrial natriuretic hormone (ANP)
 Produced when atrial pressure increases (eg heart failure)
 Promote Na+, Cl- and water loss
 Antidiuretic hormone
 Increases permability of distal tubule to water, to cinrease water
resorption (therfore increases concentration of urine)
 1,25 dihydroxy vitamin D3
 Promotes calcium absorption from gut
 Erythropoietin (EPO)
 Stimulates marrow to produce red blood cells