Micturition reflex

Micturition reflex is a physiological process that facilitates the act of urination. It involves a series of coordinated neurological and muscular events that lead to the expulsion of urine from the urinary bladder.

Overview

The micturition reflex is initiated when the urinary bladder becomes filled with urine, stretching the bladder wall and stimulating stretch receptors. These receptors send signals to the sacral region of the spinal cord, which in turn sends signals to the pontine micturition center in the brain. The brain then sends signals back to the bladder, causing the detrusor muscle to contract and the internal urethral sphincter to relax, resulting in urination.

Mechanism

The micturition reflex involves both voluntary and involuntary components. The involuntary component is mediated by the autonomic nervous system, specifically the parasympathetic nervous system, which causes the detrusor muscle to contract and the internal urethral sphincter to relax. The voluntary component involves the somatic nervous system, which controls the external urethral sphincter. When a person decides to urinate, the brain sends signals to the external urethral sphincter causing it to relax and allow the passage of urine.

Clinical significance

Disruptions to the micturition reflex can lead to various urinary disorders, such as urinary incontinence, urinary retention, and overactive bladder. These conditions can be caused by a variety of factors, including neurological disorders, urinary tract infections, and prostate enlargement.

See also

• Urinary system
• Urination
• Neurophysiology

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