Urinary bladder

The urinary bladder is a hollow, muscular organ that collects and stores urine produced by the kidneys before its eventual excretion. Located in the pelvis, just posterior to the pubic bone, the bladder plays a central role in the body's urinary system.

Urinary bladder

Anatomy

The bladder's anatomy allows it to store and expel urine:

• Mucosa: The innermost layer, lined with transitional epithelium that can stretch as the bladder fills.
• Muscularis: A layer of smooth muscle known as the detrusor muscle, which contracts to expel urine.
• Adventitia: The outermost layer, made of connective tissue.

The bladder's shape is akin to an inverted pyramid, with its apex pointing forward and downward.

Function

The primary function of the urinary bladder is to store urine until a person decides to void:

• Storage: The bladder can typically hold about 400-600 ml of urine.
• Voiding: Through a process called micturition, where the detrusor muscle contracts and the internal urethral sphincter relaxes, allowing urine to flow into the urethra.

Physiology

The filling and emptying of the bladder are regulated by a complex interplay of the:

• Central Nervous System: The brain recognizes bladder distension and can control the timing of micturition.
• Autonomic Nervous System: Especially the parasympathetic and sympathetic divisions, which control involuntary bladder contractions and relaxation of the sphincters.
• Somatic Nervous System: Helps control the external urethral sphincter, providing voluntary control over voiding.

Disorders

Various disorders can affect the urinary bladder:

• Cystitis: Inflammation of the bladder, commonly caused by urinary tract infections.
• Bladder stones: Hard masses of minerals in the bladder.
• Bladder cancer: Malignant growth in the bladder's lining.
• Overactive bladder: A condition characterized by frequent and sudden urges to urinate.
• Interstitial Cystitis: A chronic condition causing bladder pain and frequent urination.

Diagnosis and Treatment

Diagnosis of bladder conditions often involves:

• Urinalysis: Examination of urine for signs of infection, blood, or cancer cells.
• Cystoscopy: Using a thin camera to inspect the inside of the bladder.
• Imaging: Like Ultrasound or CT scans to visualize the bladder and surrounding organs.

Treatment depends on the specific condition:

• Antibiotics: For infections.
• Surgery: To remove tumors or stones.
• Bladder training: For overactive bladder, teaching individuals to resist the urge to void and gradually increase the intervals between emptying the bladder.