Anatomy & physiology of Urinary System ppt

Anatomy & Physiology of
Urinary System
Dr. Deepika R. Kenjale

The Urinary System
 One of the four excretory system in the body.
 Other three are bowel, lungs & skin.
 Components:
1. 2 Kidneys
2. 2 Ureters
3. Urinary bladder
4. Urethra

Kidneys
 Definition:
The kidneys are a pair of excretory organs situated on
the posterior abdominal wall, one on each side of the
vertebral column, behind the peritoneum.

Kidneys
 Retroperitoneal organ.
 Bean shaped, has 2 poles, 2 surfaces, 2 borders.
 Normal size: 150g in males and 135g in females; LWT:
11X6X3.
 Vertically extends: T12-L3.
 Right kidney is slightly lower than the left.

Protection of the Kidneys
1. Outer Layer- Renal fascia, anchors the
kidney to surrounding.
2. Middle Layer- Adipose Capsule, Protects
from trauma
3.Inner layer- Renal capsule, shape & prevents
it from infection.
It is partially protected by 11th and 12th

Nephron:
 Structural & functional unit of kidney.
 Each kidney has about 1-1.3 millions of nephrons.
 Nephron formed by 2 parts:
1. Renal corpuscle- blind end.
2. Renal tubule- tubular portion.
 Classified : Based on position of the renal corpuscle.
1.) Cortical Nephron- Corpuscles lies in the outer cortex , near
periphery.
2). Juxtamedullary Nephron- Corpuscle lies in the inner cortex,
near medulla
 Start decreasing after about 45-50 years of age with rate of 0.8-
1% every year.

Juxtaglomerular Apparatus
 Situated near the glomerulus of each nephron (juxta-
near).
 Formed by 3 different structures.

Main function of JGA
 GFR control
 Stimulated by high tubular NACL.
 Renin release
 Stimulated by low tubular NACL
 EPO release

 Nerve supply- Renal plexus, an offshoot of coeliac
plexus. It contains postganglionic fibers from the
sympathetic nervous system (T10 to L1) which are
Afferent nerves of kidney belong to segment T10-T12.
 Lymphatic drainage- Lymphatics drain into the lateral
aortic lymph nodes which are located at level of origin of
renal arteries.

Functions of the kidney
1. Excretory function:
a)Metabolites
b)Drugs
c)Toxins
2.Homeostatic function:
Maintenance of water balance, electrolyte balance, acid base balance.
3. Endocrine (hormonal) secretary function:
a)Renin – JG cells. (regulates blood pressure)
b)Erythropoietin- Endothelial cells of peritubular capillaries of renal cortex.
c)Prostaglandins- PGE2 is synthesized in medulla, PGI2 is synthesized by renal vessels
and glomeruli
4. Metabolic function:
Plays important role in vitamin D metabolism.

Ureters
 Pair of narrow, thick walled muscular tubes which
transport urine from kidneys to urinary bladder.
 Size-25 cm (10 in.-> upper half lies in abdomen and lower
half in pelvis). 3mm in diameter.
 The urine is propelled from the kidneys to the urinary
bladder by the peristaltic contraction of the smooth
muscle of the wall of the ureter.

• Blood supply:
1. Upper part- Renal artery, m/a gonadal , or colic
vessels.
2.Middle part- Abdominal aorta, m/a gonadal or
iliac vessels.
3.Pelvic part- Vesical, middle rectal or uterine
vessels.
• Nerve supply:
Sympathetic T10-L1 segments
ParasympatheticS2-S4 nerves

Urinary Bladder
 It is a muscular reservoir of urine.
 Empty bladder is tetrahedral in shape whereas full bladder is
ovoid in shape.
 Mean capacity-220ml.
 Urinary bladder gets emptied through the urethra.

Urethra
 Urethra, duct that transmits urine from
the bladder to the exterior of the body
during urination.

Anatomy & physiology of Urinary System ppt

Anatomy & physiology of Urinary System ppt

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Anatomy & physiology of Urinary System ppt