URINARY SYSTEM

The Urinary System is a group of organs in the body concerned with filtering out excess fluid from the body in the form of urine.
The Urinary organs include:

1. KIDNEYS
2. URETERS
3. BLADDER
4. URETHRA

Urine is a liquid produced by the kidneys, collected in the bladder and excreted through urethra.

KIDNEYS

• The kidneys are two, bean-shaped organs that are located in the back part of the abdomen, on either side of the spine and approximately between the twelfth thoracic and third lumbar vertebrae.
• Often, the left kidney is positioned up to an inch higher than the right kidney.
• Each kidney is about 4-5 inches long and about two inches thick, weighing 4-6 ounces in the average adult.
• Because of the presence of many blood vessels, the kidneys are colored a dark reddish-brown.

ANATOMY OF THE KIDNEY

CORTEX: The cortex of the kidney is the outer section which covers the internal medulla. The cortex is visible near the outer edge of the cross-sectioned kidney. It is composed of blood vessels and urine tubes and is supported by a fibrous matrix.

CALYX: The calyces (plural for calyx) are the recesses in the internal medulla of the kidney and they are used to subdivide the sections of the kidney anatomically.

PYRAMID: The renal pyramids are conical segments within the internal medulla of the kidney. The pyramids contain the secreting apparatus and tubules and are also known as the malphighian pyramids.

NEPHRONS:

• A nephron is the basic structural and functional unit of the kidney.
• About one million nephrons are in the cortex of each kidney.
• Its chief function is to regulate water and soluble substances by filtering the blood, reabsorbing what is needed and excreting the rest as urine.
• Each nephron has its own supply of blood from two capillary regions from the renal artery.
• Each nephron is composed of an initial filtering component (the renal corpuscle) and a tubule specialized for reabsorption and secretion (the renal tubule).
• The renal tubule consists the convoluted tubule and the loop of Henle.

GLOMERULUS:

• The glomerulus is the main filter of the nephron and is located within the Bowman's capsule.
• The glomerulus resembles a twisted mass of tiny tubes through which the blood passes.
• The glomerulus is semipermeable, allowing water and soluble wastes to pass through and be excreted out of the Bowman's capsule as urine.

BOWMAN'S CAPSULE:

• The Bowman's capsule contains the primary filtering device of the nephron, the glomerulus.
• Blood is transported into the Bowman's capsule from the afferent arteriole . Within the capsule, the blood is filtered through the glomerulus and then passes out via the efferent arteriole.
• Meanwhile, the filtered water and aqueous wastes are passed out of the Bowman's capsule into the proximal convoluted tubule.

PROXIMAL CONVOLUTED TUBE: Coiled and lined with cells carpeted with microvilli and stuffed with mitochondria.

LOOP OF HENLE: It makes a hairpin turn and returns to the Distal convoluted tubule, which is also highly coiled and surrounded by capillaries.

COLLECTING TUBULE: It leads to the pelvis of the kidney from where urine flows to the bladder and, periodically, on to the outside world.

FORMATION OF URINE

1.The nephron makes urine by filtering the blood of its small molecules and ions and then reclaiming the needed amounts of useful materials.

2.Surplus or waste molecules and ions are left to flow out as urine.

URETERS, BLADDER AND URETHRA

URETERS : The ureters are two tubes that drain urine from the kidneys to the bladder. Each ureter is a muscular tube about 10 inches (25 cm) long.

BLADDER: The bladder is a muscular sac where urine is stored to be released from the body. It can hold between 0.6 litres of urine before it needs to be emptied. The external bladder stores the urine. The voluntary action controls the external muscle sphincter which opens only when the desire to void arises .

URETHRA: The urethra is a muscular tube that connects the bladder with the outside of the body. The function of the urethra is to remove urine from the body.

MEDICAL TERMS

Glomerulonephritis – Inflammation of the kidney which may be acute or chronic.
Cystitis – Inflammation of the urinary bladder.
Nephrolithiasis – Presence of stone in the kidney.
Polycystic kidney – Hereditary condition where there is enlargement of kidney due to formation of any cysts.
Pyelonephritis – Inflammation of renal pelvis.
Renal failure – Failure of kidney to maintain normal function. It may be acute or chronic. Grawitz tumor (renal carcinoma) – Cancer of the kidney.
Wilms tumor (nephroblastoma) – Malignant tumor of the kidney which occurs in young children.
Diuresis – Increased secretion of urine.
Urinary retention – Inability to pass urine.
Urinary incontinence – Inability to keep urine in the bladder.
Urinary tract infection (UTI) – Inflammation and infection of the urinary tract.
Anuria – Cessation of secretion of urine.
Oliguria – Decreased secretion of urine.
Diuria, dysuria – Difficulty in passing urine.
Polyuria – Increased secretion of urine.
Dehydration – Loss of water content from the body.
Uremia – Presence of excess urea in the blood.
Diabetes insipidus – Condition marked by increased flow of urine of low specific gravity accompanied by excessive thirst.
Urinary bladder spasm – Sudden involuntary contraction of the bladder.
Cancer of the bladder – Malignant tumor or growth of the bladder.
Interstitial nephritis – Chronic inflammation of kidneys associated with fibrosis and hypertension.
Hydronephrosis – Dilation of pelvis due to obstruction in ureter.
Nephropathy – Disease of the kidney.
Nephrotic syndrome – Disorder characterized by protein loss from kidney resulting in edema.
Renal artery stenosis – Blockage of renal artery.
Renal cell carcinoma – Malignant tumor.
Renal hypertension – Increased blood pressure due to kidney disease.
Ureteritis – Inflamation of the ureter.
Urethritis – Inflammation of the urethra.
Vesicoureteral reflux – Recurrent urinary tract Infection due to back flow.
Flank pain – Abdominal pain.
Pyuria – Puss in the urine.
Hematuria – Blood in the urine.

LABORATORY TESTS

1. URINE
2. Routine and culture
3. Urinalysis
4. Blood, urea, nitrogen (BUN)
5. Creatinine
6. Glucose
7. Uric acid

DIAGNOSTIC PROCEDURES

• Cystogram
• Intravenous pyelography
• Ultrasound
• Cystoscopy
• Urethroscopy

TREATMENT PROCEDURES

• Urostomy
• Ureteronephrectomy
• Urethrolithotomy
• Nephrolithotomy
• Allograft
• Bladder diverticulectomy
• Kidney dialysis
• Kidney transplantation
• Lithotripsy
• Nephrectomy
• Pyeloplasty
• Urinary catheterization (Cystoscopy, cystoureteroscopy, cystourethroscopy)