Lecture 65 - continence & micturition Flashcards
micturition
deliberate urination as an autonomic reflex facilitated by higher brain centers
continence
ability to voluntarily retain bodily discharge
urinary continence requires what 3 things
- urethral pressure > bladder pressure
- functional neurologic control/innervation
- bladder and urethra both within abdominal cavity
detrusor muscle relaxation
- relaxed for urine storage
- controlled by SNS
- Beta receptors in bladder wall
detrusor muscle contraction
- voiding of urine
- controlled by PNS
- Ach activates muscarinic receptors
internal urethral sphincter
- smooth muscle (involuntary control)
- controlled by SNS (alpha adrenergic)
- tonic contraction
external urethral sphincter
- skeletal muscle (voluntary control)
- associated with pelvic floor muscles
hypogastric n
- sympathetic L1-L4
- innervates bladder and IUS
pelvic n
- parasympathetic S1-S3
- ascending sensory
- detrusor muscle contraction
pudendal n
- somatic S1-S3
- innervates EUS
describe the storage phase
- sympathetic and voluntary control
- Hypogastric n. - norepinephrine acts on B receptors to relax muscles and on a receptors to tighten urethral sphincters
- pudendal n. - Ach binds nicotinic receptors for contraction
describe the voiding phase
- PNS and voluntary control
- pelvic n. - Ach binds muscarinic receptors to increase the tone of detrusor muscle
- higher brain centers decrease pudendal activity and inhibit activation of hypogastric n.
summarize continence and micturition in 4 steps
- bladder fills, detrusor m. relaxes, urethral sphincter and pelvic floor contracts
- first sensation to void
- normal desire to void
- micturition, pelvic floor relaxes, detrusor muscle contracts
common 3 causes of incontinence
- urethral incontinence
- ectopic ureter
- overflow incontinence (upper or lower motor neuron)
urethral incontinence
IUS - age, loss of estrogen
EUS - skeletal mm disease or loss
tx aimed at increased IUS or increasing muscle strength
ectopic ureter
ureter bypasses bladder or goes directly into urethra causing leaking
overflow incontinence
pressure in bladder > sphincter control
urethral blockage, loss of detrusor mm., loss of ascending info regarding bladder stretch
upper motor neuron bladder
central lesion between brain and L7
loss of bladder fullness sensation and voluntary micturition, loss of signal to initiate contraction
large turgid bladder and difficult to express due to spastic EUS
lower motor neuron bladder
spinal cord or peripheral nerve lesion at sacral spine or associated nerves
los of both pelvic and pudendal nerve function, variable size bladder, easily expressed, more likely to leak
