THE URINARY SYSTEM
Bladder: it is a pear-shaped urinary reservoir when empty, but assumes a balloon shape went
full. It is also a pelvic organ, depending on whether full or empty.
Draw the bladder
The Bladder is a hollow muscular distancesible organ of micturition that rests on the pelvic floor.
It rises to become an abdominal organ from the pelvis
Function
-To store and expel urine
External feature
Empty bladder has
-Apex
-Base
-Neck
When full, it has an oval/balloon in ship, and Apex is pointed towards the unibilicus, neck which is
directed downwards, and in an anterior and posterior surface. Externally, the neck is the most
fixed and is at the lower portion of the bladder. The base is directed backwards.
Wall of the bladder
The wall
The inner mucus layer which has epithelium that readily allows distension (rugae) of the bladder
as it fills
1. The middle layer composed of smooth muscle Fibers and elastic tissues arranged in three
layers called the dextrusor muscle. It’s contraction leads to the emptying of the bladder.
Trigone
The Ureter enter the bladder posteriorly. The two orifices of the bladder, and that of the urethral
opening forms the trigon of the bladder.
The bladder capacity
As the bladder fills, there is an awareness of the need to micturate (void or urinate) The capacity
of the bladder is about 600 ml approximately 2 cups. The initial awareness is created when the
bladder content reaches about 200 to 300ml. It is recommended that an individuals should
micturate 4-8 or 6-9 in a 24 hour period. The bladder capacity increases with age. In men,
capacity of about 200 to 300ml will start illicit the urge to micturate. In women, the urge starts
from 250 to 350ml.
Urethra
The Urethra is conduct through which urine exits the bladder to the exterior. It extends from the
neck of the bladder to the exterior of the external urethral orifice(opening). There is significant
difference between the Male and female urethra
Male urethra
Draw the male urethra
The average male urethra is about 20 cm long that starts from the bladder wall and ends in the
distal gland of the penis. It performs, but urinary and sexual functions that is passage of urine
and semen.
Blood supply: inferior vesical artery
bulbourethral artery
Innervation: Prostatic plaxus
Parts of the Urethra
1. Pre-prostatic urethra 0.5 - 1.5 cm in length
2. Prostatic Urethra 3.0 - 4.0 cm in length
3. Membranous Urethra. 1 to 1.5 cm in length
4. Spongy Urethra 15 cm in length
Sphincters are the external urethral sphincter at first below the prostate which is on the
voluntary control. The outward sphincter is under involuntary control located just above the
prostate
Female Urethra
The female urethra is about 4 cm in length, and 6 cm in diameter. The internal and external
urethra sphincter is located at the neck of the bladder and the external at the urethra’s distal end
respectively.
The walls
1) outer muscular layer; inner smooth of the outer muscle
2) Inner mucosal layer
The inner portion of the muscle layer is under voluntary control and it forms the external
urethral sphincter
Micturition
