Urinary Sytem Physiology

Physiology

The urine is produced in the kidneys, then in the renal pelvis and then through the ureter into the bladder emptying. Whose wall is filled by the growing stretched, by what is perceived strain sensors. This triggers parasympathetic centers in the sacral spinal reflex one, the so-called Miktionsreflex, from the contraction of the detrusor muscle in the bladder wall and a relaxation of the internal sphincter triggers. The part of this reflex located in the nerve pelvinus. Only when the conscious relaxation of the external sphincter is starts urination. This deliberate control of the external sphincter may, however, very strong filling of the bladder through the nerve pudendus derived inhibitory impulses cease to be valid.

The urination is autonomous reflexes in the sacral spinal cord controls on the higher areas of the central nervous system influence by either inhibit or stimulate. In the brainstem, specifically in the pons (bridge) are centers, the inhibiting and stimulating effect on the Miktionsreflex (Pontine Miktionszentrum, part of the Formatio reticularis). Remains found in the cerebral cortex centers, which are mainly inhibitory, but under certain circumstances can intervene stimulant. The Miktionsreflex is the main cause of urination, but the final responsibility of checking these higher centers. They inhibit the reflex, except when the urination deliberately sought, they can urination by the contraction of the external sphincter delay and they can initiate urination, by stimulating the sacral centers.

Any urination begins by the abdominal muscles are tense. This pushes the bladder and increases the pressure. This presses the urine in the bladder neck and urethra, which will strain sensors excited, and thus the Miktionsreflex triggers. Furthermore, an inhibition of the external sphincter. After undisturbed, not prematurely urination remain usually no more than five to ten milliliter urine in the bladder.

The first exercise of Harnansammlung in the bladder occurs in humans at around 80 ml. At approximately 300 to 500 ml is the need to, to empty the bladder.