Urinary system|brief description|check anatomy and clinical notes about urinary system obstruction

Urinary system

Urinary system consist of a pair of kidneys,ureters and bladder and urethra.Its function is to eliminate wastes from the body.regulate blood volume,pressure and blood pH,it also helps synthesize calcitrol,regulates electrolytes and metabolites.
Let's discuss one by one the elements or organs in urinary system.

Kidney

There is a pair of kidneys that lie behind the peritoneum high up on the posterior abdominal wall on either side of vertebral column. It is a bean shaped organ and has an outer cortex which is dark brown in colour and the inner medulla is light brown.The medulla is composed of approximately 12 renal pyramids,each having its base oriented towards the cortex and its apex(the renal papilla) projecting medially.The cortex projects into medulla between adjacent pyramids as renal columns.
On the medial concave border of each kidney is the hilus,which extends into a large cavity (the renal sinus),The hilus transmits the renal pelvis, renal artery,renal vein and sympathetic nerve fibers.
Major and Minor calyces
Within the renal sinus,the upper expanded end of the ureter (renal pelvis)divides into two or three major calyces,each of which in turn divides into two  or three minor calyces
The kidney has the four coverings which are:

• Fibrous capsule-present on the outer surface
• Perirenal fat-covers the fibrous capsule
• Renal fascia-present outside the perirenal fat and also covers suprarenal glands along with kidneys.
• Pararenal fat-external to renal fascia.

Blood Supply

Artery

• Renal artery,branch of aorta 

Vein

• Renal vein drain into inferior vena cava.

Ureters

The two ureters are muscular tubes, each measures about 10 inches in length extends from the kidney to the posterior surface of bladder.Ureters carry urine from kidneys to bladder.Renal pelvis is its upper extended end.

Clinical Findings

Ureteric stones may be arrested at the following sites

• where the renal pelvis joins the ureter
• where the ureter is kinked as it crosses the pelvic brim to enter the pelvis
• where the ureter pierces the bladder wall.

Blood supply

Arteries

• Upper end-renal artery
• Middle portion-The testicular or the ovarian artery
• Inferior end-The superior vesical artery

Veins

• renal vein drains into inferior vena cava

Bladder

It is pyramidal in shape or tetrahedral, when empty and becomes ovoid when filled with urine.It has an apex,base, superior surface,two inferolateral surfaces and four borders(anterior,posterior and two lateral)
It is present immediately behind the pelvic bones behind the pubic symphysis and in front of rectum in the female.When the bladder is empty it lies entirely within the lesser pelvis but when it becomes distended with urine, it expands upward and forward into the abdominal cavity.

Relations

• Apex connected to the umbilicus by median umbilical ligament
• superolateral angle joined by ureters
• inferior angle give rise to urethra
• base or posterior surface is triangular,rectovesicle pouch in male and vesico uterine pouch in the female

In adult male the capacity of bladder to store urine is from 120 to 320ml. The mean capacity is about 220ml.An amount of urine beyond 220ml causes a desire to micturate.

Ligaments

The ligaments of the bladder are of two types:

True ligaments

• lateral ligaments(right and left)
• Puboprostatic ligaments(two on lateral and medial side)
• posterior ligament(right and left)

False ligaments

• Anteriorly there are three folds
• Laterally a pair of false lateral ligaments
• Posteriorly a pair of false posterior ligaments

Blood supply

Arteries

• Superior and inferior vesical arteries
• Obturator and inferior gluteal arteries
• Uterine and vaginal arteries in female

Veins

Vesical venous plexus passes backward in the posterior ligaments of the urinarybladder to drain into the internal illiac veins.

Urethra

The urethra is a narrow fibromuscular

 tube that connects the urinary bladder to the urinary meatus.Its function is the removal or transport of urine outside the body.In males, the urethra travels through the penis and in female the urethra connects to the urinary meatus above the vagina.

Blood supply

Arteries

• Inferior vesical artery
• Middle rectal artery
• Internal pudendal artery

Veins

• Inferior vesical vein
• Middle rectal vein
• Internal pudendal vein

Obstruction of the urethra

Obstruction of the urethra causes urinary retention. Conditions such as prostatic hyperplasia, cystocele, .rectocele,constipation,urinary tract stones,urethral stricture can cause an obstruction.