Bladder
Functions of the bladder
- Storage of urine (up to 500mls+)
- Prevents organisms ascending urinary tract
Nerve supply of bladder
- PNS: to Detrusor muscle contraction
- SNS (with hypogastric nerves) L1,2,3: alpha-1 contraction of sphincter, B2 relaxation of detrusor
- Pudendal nerve to external sphincter
Micturition
- Storage
- Receptive relaxation, progressive filling without much increase in pressure
- 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
