bladder

The bladder As an elastic hollow organ, it is primarily used to store urine until it is emptied via the urethra. The urinary bladder can be affected by many different disorders of psychological and / or somatic origin.

What is the urinary bladder?

Schematic representation of the anatomy and structure of the urinary bladder. Click to enlarge.

As Urinary bladder (Vesica urinaria) is a stretchable muscular hollow organ that rests on the pelvic floor in the small pelvis directly behind the pubic bone (OS pubis) and serves to absorb and temporarily store urine.

When empty, the urinary bladder is compressed like a limp sack by the bowels in the abdominal area.If the vesica urinaria slowly fills with urine, which reaches the bladder body of the hollow organ via the two ureters (ureters) from the renal pelvis, it expands like a ball as the volume increases.

In women, the urinary bladder borders the uterus (womb) in the back of the pelvis, while in men it closes off towards the rectum (rectum).

Anatomy & structure

The bladder is localized in the small pelvis, where it connects to the pubic symphysis and extends upwards to the upper edge of the pelvis.

It can be divided into different areas. The cranial (upward) surface has a peritoneal coating (serosa or peritoneum) and is also known as the apex vesicae. The actual bladder body (corpus vesicae), in which the urine arriving from the kidneys is temporarily stored, lies directly below and is bounded by the base of the bladder (fundus vesicae).

On the lower side there is also the cervix vesicae (neck of the bladder), which tapers like a funnel towards the urethra. The mouths of the paired ureters (ureters) and the exit of the urethra form the so-called Trigonum vesicae (bladder triangle). In the area of ​​the urethral orifice, the urinary bladder has an inner and an outer sphincter (sphincter muscles), whereby only the outer, striated urethral muscle is subject to conscious control by humans.

The urinary bladder is also anchored in the pelvic floor by various band-like serosa duplicates (peritoneum folds). On the inside, the urinary bladder is lined with a layer of mucus as protection against the urine. The outer layer of the urinary bladder, on the other hand, consists of smooth muscles (detrusers).

Functions & tasks

The hollow organ serves bladder primarily the intermediate storage of the secondary urine from the kidney until it is emptied via the urethra. The elasticity of the urinary bladder ensures that it can hold between 900 and 1500 ml of urine, with an adult urinating from around 300 to 500 ml.

During emptying (micturition) the smooth muscles (detrusor) of the bladder contract while the sphincter muscles at the base of the bladder relax, so that the urine is pushed out of the lumen via the urethra. Although the kidneys allow urine to flow continuously through the ureters into the bladder, the external sphincter, which is subject to conscious control by humans, ensures that the urine is emptied from time to time, although the accompanying processes are reflexive.

As the filling volume increases, the bladder wall expands and tensions, which is sensed by the expansion sensors located in the wall, which trigger the so-called micturition reflex in the parasympathetic centers of the spinal cord. This in turn causes a contraction of the smooth muscles of the bladder wall (Musculus detrusor), which leads to an outflow of urine through the urethra with simultaneous relaxation of the outer striated sphincter. This process is also supported by the contraction of the abdominal and pelvic muscles.

Diseases

The bladder can be affected by a variety of acquired or genetic impairments. One of the most common bladder diseases is cystitis or inflammation of the bladder, which is usually due to an infection ascending through the urethra.

Women in particular are affected by bladder infections due to the shorter urethra. A disruption of the locking mechanism can cause urinary incontinence (involuntary leakage of urine), which can be triggered by both psychological (stress) and physiological factors such as paraplegia, detruser-sphincter dyssynergy or Parkinson's disease.

A cystocele is a protrusion of the urinary bladder into the anterior vaginal wall in women. It occurs in connection with a weak pelvic floor, usually combined with a sagging of the vagina.

Urinary congestion as a result of prostatic hyperplasia can lead to overstretching of the bladder (vesica gigantea) and incomplete emptying of the bladder (residual urine). Clinically relevant residual urine is also a symptom of strictures, stenoses or benign hyperplasia or malignant prostate cancer. Tumor diseases of the bladder are very common in Germany and are among the most widespread types of tumors, with urothelial carcinomas (malignant bladder mucosal tumors) being the most common at 95 percent.

If there is a permanent irritation, for example as a result of hypothermia, it is referred to as an irritable bladder in which even small quantities trigger the micturition reflex. In addition, bar-like hypertrophy (thickening) of the bladder muscles (so-called bar bladder) leads to a reduced ability to contract, which can cause residual urine and urinary tract infections.

External trauma (violence) can lead to a rupture of the urinary bladder (urinary bladder rupture) in addition to a rupture of the pelvis with symptoms such as pelvic pain and urge to urinate with simultaneous urinary retention.

Typical & common bladder diseases

• Cystitis
• Incontinence (urinary incontinence)
• Urinating at night (nocturia)
• Bladder weakness