process of emptying bladder

involves progressive filling causing increased bladder tension, initiating a nervous reflex

Reflex

• autonomic spinal cord reflex, inhibited or facilitated by centres in brain stem and cerebral cortex
• causes conscious desire to urinate
• Receptor: sensory stretch receptors in bladder wall (particularly b/w int and ext sphincters)
• Afferents: pelvic nerves
• centres - higher centres keep micturition reflex partially inhibited, preventing voiding even with reflex activation due to tonic contraction of external sphincter
  • Facilitatory: Pons, posterior hypothalamus
  • inhibitory: midbrain, cerebral cortex (external sphincter control)
• Efferents - pelvic nerves
• Effector organs - detrusor muscles, internal and external sphincters

SNS stimulation → filling

PNS stimulation → voiding