L2 - Urine Production and Micturition 2

Innervation

Sensory signals from bladder and urethra.

Stretch receptors

Detect fullness in the bladder wall.

Pelvic nerves

Relay signals to sacral spinal cord.

Afferents from urethra

Detect flow, distension, and pain.

Pudendal nerve

Transmits signals from urethra to spinal cord.

Micturition centre

Located in the pons, controls urination.

Bladder stretch receptors

Respond to bladder fullness and send impulses.

Urethralis muscle

Relaxes to allow urine flow during micturition.

Detrusor muscle

Contracts to empty the bladder during urination.

Cerebral cortex

Involved in voluntary control of micturition.

Sympathetic control

Maintains urine storage in the bladder.

Urethral sphincters

Prevent urine leakage through contraction.

α-adrenergic stimulation

Constricts internal sphincter at bladder neck.

External sphincter tone

Maintained by pudendal nerve to prevent outflow.

β-adrenergic receptors

Relax detrusor muscle for bladder filling.

Hypogastric nerves

Inhibit pelvic nerves during bladder filling.

Parasympathetic control

Facilitates bladder emptying when full.

Integration at micturition centre

Coordinates bladder contraction and sphincter relaxation.

Adrenergic tone

Inhibition allows internal sphincter to relax.