Micturition Flashcards
What is responsible for continence ?
Intrinsic sphincter - bladder neck muscle fibers mid-urethral (membrane/prostate in males) complex
What interrupts stream?
rhabdosphincter
Parasympathetic innervation (Pelvic nerve s2-4)
Detrusor muscle - micturition upon contraction
Motor innervation (CNS)
bladder, pelvic floor, urethral sphincter (s2-4) - sensation of bladder fullness or stretch are conveyed through long neurons from spinal cord to pons
Sympathetic (ANS)
T10-L2 = Inhibits detrusor and increases tension in the smooth muscle of the bladder neck and proximal urethra
Higher order control
Cortex - inhibitory over sacral centers (think disease and incontinence / stroke)
Cerebellum/Brainstem - facilitory
Root with motor
ventral
Root with sensory
dorsal
Dysfunction of bladder storage phase (normally neuromuscular adaption allows minimal pressure change with increased volume) — dysfunction
frequency, urgency, and urge incontinence - OAB
Storage phase
allows bladder to adapt to increasing volume with little changes in pressure (affarent pelvic nerve fibers to DRG) (Efferent pudendal via VH - inhibit detrusor - somatic and cortical)
What causes detrusor contraction
PS of pelvic nerve
2 functions of bladder
store and empty urine
Urine empty must override storage - dysfunction
hesitancy / weak stream / incomplete empty
5 steps of bladder emptying
increase in bladder wall tension
affarent input overcomes pontine micturition center threshold and povides cortical egress micturition begin
pudendal nerve (SMN) activity ceases (relax), the external sphincter and pelvic floor relaxes (SN), detrusor neurons (PS) are freed and discharge
proxmial urethra opens
bladder immediately contracts
micturition cycle dysfunction
hesitancy / weak stream / retention
efferent response to bladder filling?
pudendal s2-s4 (somatic) - associated with cortical inhibition of detrusor
step 1 voiding?
increase wall tension in bladder
Step 2 voiding (After increase in wall tension)
affarent input overcomes the pontine micturition center threshold and provides cortical egress –> micturition begins
step 3 voiding (After cortical egress initiates micturition)
- pudendal (SMN) relax
- External sphincter/pelvic floor relax (SM)
- Detrusor (PS) freed from inhibition
Step 4 voiding (after inhibition ceases)
proximal urethra opens
step 5 voiding (after urethra opens)?
bladder contracts
what monitors bladder?
pelvic nerve affarents
somatic pudendal nerves?
constrict urethral sphincter
lumbar sympathetic nerves
inhibit bladder
constrict sphincter
pelvic PS nerves
contract blader
inhibit sphincter contraction
2 main causes of incontinence
stress
urge
OAB (urge) usually due to?
neurological problem
treat with Anticholinergics
drug for OAB
Oxybutynin
CytP450 3A4
Dries you out
involuntary sudden loss of urine during increases in intra abdominal pressure
Stress incontinence
Treat stress incontinence with?
ephedrine
estrogen
UTO most common in men?
BPH
BPH symptoms UTO
Frequency / urgency /
Hesitancy / decreased stream
Storage issues
frequency urgency
emptying issues
hesitancy straining weak stream
% 80 year olds with BPH
80
50% with symptoms
% 50 year olds with BPH
25%
Treat BPH?
5-alpha reductase inhibitor
alpha1 blocker
combo
surgery
Young Men UTO
Urethral stricture often from trauma
PS NERVE
pelvic (bladder)
Sympathetic Nerve
Hypogastric (T10-L2)
detrusor / urethra / bladder neck
Motor (Somatic) Nerve
Pelvic
pelvic floor
external sphincter
