Urinary tract

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Urinary system

The urinary tract constitutes the body's drainage system for the removal of urine, a waste product formed through the filtration of blood. Urine comprises waste materials and excess fluids, including electrolytes, hormones, and water. The tract ensures the efficient elimination of these wastes while maintaining the body's crucial balance of salt and water. The urinary system plays an essential role in the overall homeostasis processes of the body.

Components

The urinary tract consists of:

• 1. Kidneys: Bean-shaped organs located on either side of the spine, below the rib cage, responsible for filtering blood to produce urine. Each kidney contains around a million tiny structures called nephrons, which are the functional units responsible for filtration and reabsorption processes.
• 2. Ureters: Thin tubes of muscle, one on each side of the bladder, that transport urine from the kidneys to the bladder. The ureters' synchronized contractions, known as peristalsis, propel the urine forward.
• 3. Urinary bladder: A hollow, muscular organ that stores urine until it is expelled from the body. It has receptors that communicate with the brain regarding its fullness level.
• 4. Urethra: The canal through which urine is discharged out of the body. Its length and function vary between males and females. In males, it carries both urine and semen, while in females, it exclusively carries urine.

Physiology

The urinary system functions via a combination of mechanical and chemical processes. The kidneys, being the primary filtering agents, remove waste materials from the bloodstream. This filtration process involves three primary steps:

• Filtration: Blood passes through the nephrons, where water and solutes (like glucose, amino acids, and urea) are separated.
• Reabsorption: Vital substances and water are reabsorbed into the bloodstream.
• Secretion: Active transport of harmful molecules from the bloodstream into the filtrate.
• The resultant filtrate, after undergoing these processes, forms the urine, which then flows into the ureters, gets stored temporarily in the bladder, and is finally excreted via the urethra.

Disorders and Diseases

The urinary tract can be susceptible to various disorders and diseases, including:

• Infections: Urinary tract infections (UTIs) are common, especially in females, and can affect any part of the urinary system.
• Kidney Stones: Hard deposits made of minerals and salts that can form inside the kidneys.
• Bladder Control Issues: Such as incontinence, where there's a loss of bladder control, and overactive bladder, where there's a frequent urge to urinate.
• Chronic Kidney Disease: A gradual loss of kidney function over time.
• Polycystic Kidney Disease: A genetic disorder causing numerous cysts to grow in the kidneys.

Diagnostic Tools

Several tools can help diagnose urinary system diseases:

• Urinalysis: Examination of urine for various cells and chemicals.
• Ultrasound: Imaging test to visualize the kidneys and surrounding structures.
• CT Scan: Detailed imaging that can detect stones, tumors, and other abnormalities.
• Cystoscopy: Examination of the bladder's interior using a thin, lighted instrument.

Anatomy

The urinary tract includes two kidneys, two ureters, a bladder, and a urethra.

• Kidneys. Two bean-shaped organs, each about the size of a fist.
• Ureters. Thin tubes of muscle that connect your kidneys to your bladder and carry urine to the bladder.
• Bladder. A hollow, muscular, balloon-shaped organ that expands as it fills with urine.
• Urethra. A tube located at the bottom of the bladder that allows urine to exit the body during urination.

Muscles of the urinary tract

The urinary tract includes two sets of muscles that work together:

• The internal sphincter muscles of the bladder neck and urethra stay closed until your brain sends signals to urinate.
• The external sphincter muscles surround the internal sphincter and provide extra pressure to keep the urethra closed. You can consciously squeeze the external sphincter and the pelvic floor muscles to keep urine from leaking out

Common urinary tract problems

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Depiction of a lady who has a Urinary Tract Infection (UTI)

• Balanitis circinata

• Bladder stone

• Emphysematous cystitis

• Enuresis

• Eosinophilic cystitis

• Fournier gangrene

• Fowler's syndrome

• Hydrocele

• Kidney stone disease

• Loin pain hematuria syndrome

• Lower urinary tract symptoms

• Malakoplakia

• Micturition syncope

• Nephrogenic adenoma

• Obstructive uropathy

• Ovarian vein syndrome

• Paruresis

• Peutz–Jeghers syndrome

• Pneumaturia

• Pseudodyssynergia

• Purple urine bag syndrome

• Renal colic

• Renal stone formation in space

• Retroperitoneal fibrosis

• Transurethral resection of the prostate syndrome

• Urinary tract infection

• Urinary tract obstruction

• Urinoma

• Zellweger syndrome

See Also

• Renal physiology
• Nephrology
• Urology
• Kidney function tests
• Dialysis

Urinary tract Resources
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