Functions of the bladder

1. Storage of urine (up to 500mls+)
2. Prevents organisms ascending urinary tract

Nerve supply of bladder

1. PNS: to Detrusor muscle contraction
2. SNS (with hypogastric nerves) L1,2,3: alpha-1 contraction of sphincter, B2 relaxation of detrusor
3. Pudendal nerve to external sphincter

Micturition

1. Storage
   • Receptive relaxation, progressive filling without much increase in pressure
2. Voiding
   • Bladder fills, stretch receptors send signals via posterior roots to sacral cord and brain (desire to void)
   • Higher centers intervene - to wee or not to wee
   • Urethral relaxation (-symp), detrusor contraction (+para)
   • Simultanous relaxation of pelvic floor muscles

Cord Bladder

• Occurs in spinal injury above L5
• Detrusor-sphincter dyssnergia
• Voiding still occurs but also get considerable urinary retention