THE URINARY SYSTEM anatomy and physiology

The urinary system

1. THE URINARY SYSTEM
Prepared by : -Varsha Patel
Nursing Officer

2. INTRODUCTION
The Urinary System is the main excretory system and consists of the
following structures :-
1.Two kidneys, which secrete urine
2.Two ureters, conveys the urine from the kidneys to the urinary
bladder
3.The urinary bladder, which collects and stores urine
4.The urethra, through which urine leaves the body

4. KIDNEYS
•Kidneys are bean shaped organs
•About 11cm long, 6cm wide, and 3cm
thick
•They weigh around 150 g
•Lie on the posterior abdominal wall,
one on each side of the vertebral
column, behind the diaphragm.
•They extend from the 12
th
thoracic
vertebra to 3
rd
lumbar vertebra
•The right kidney is lower than the left
kidney because of space occupied by
the liver.

5. Structure of kidney
•Kidney consists of 3 layers of tissues
-
•An outer fibrous capsule,
surrounding the kidney
•The cortex, a reddish-brown layer of
tissue below the capsule
•The medulla, innermost layer
consisting of renal pyramids
•Kidneys contains 1-2 million
functional units, the nephrons, and
a much smaller number of
collecting ducts.

6. The Nephron
•The nephron is essentially a tubule that is closed at one end and
opens into a collecting duct at the other end.
•The closed or blind end forms the cup-shaped glomerular (Bowman's)
capsule, which almost completely encloses a coiled tuft of capillaries,
the glomerulus.
•the nephron is about 3 cm long and described in three parts:
-the proximal convoluted tubule
-the medullary loop (loop of Henle)
-the distal convoluted tubule, leading into a collecting duct.

7. Structure of nephron

8. Functions of kidneys
•Formation of urine
•Maintaining water and electrolyte balance
•Maintaining acid-base balance
•Excretion of waste products including urea, uric acid, excess ions and
excreted drugs
•Production and secretion of erythropoietin hormone
•Production and secretion of renin enzyme

9. URETERS
•The ureters carry urine from the
kidneys to the urinary bladder
•They are hollow muscular tubes
about 25-30 cm long with 3 mm
diameter
•It is continuous with the funnel
shaped renal pelvis

10. Structure of ureters
•A outer covering of fibrous connective
tissue
•A middle muscular layer consisting of
smooth muscle fibres
•An inner layer, the mucosa composed
of transitional epithelium

11. Function of ureters
•Peristalsis, propels the urine along the ureter
•Transfers urine from kidney to urinary bladder

12. URINARY BLADDER
•Theurinary bladder is a reservoir for
urine.
•It liesinthepelviccavity
•it’s size and position vary depending on
the volume of urine it contains.
•When distendedbladderliesintothe
abdominalcavity.

13. Structure of urinary bladder
•The bladder (Fig.13.19) is roughly pear-shaped, but becomes more
balloon-shaped as it fills with urine.
•The posterior surface is the base.
•The bladder opens into the urethra at its lowest point.
•The bladder wall is composed of three layers:
-The outer layer of loose connective tissue
-The middle layer, consisting of interlacing smooth muscle fibresand
elastic tissue loosely arranged in three layers.
-The inner mucosa, composed of transitional epithelium that readily
permits distension of the bladder as it fills.

14. Urethra
•The urethra is a canal extending from the neck of the bladder to the
exterior, at the external urethral orifice.
•It is longer in the male than in the female.
•The male urethra is associated with both the urinary and the
reproductive systems.
•The female urethra is approximately 4 emlong and 6 mm in diameter.

15. Female
urethra

16. Male
urethra

17. Bibliography
•Ross & Wilson, ANATOMY AND PHYSIOLOGY in health and illness, 13
th
edition.