Movement of Urine / Micturition Flashcards
upper urinary tract
calyces
pelvis
ureteres
bladder
stores urine under low pressure
expels under high pressure
urethra
way to expel urine
has sphincter
internal sphincter
smooth muscle (involuntary)
external sphincter
skeletal muscle (voluntary) -where urethra joins bladder
afferent pathways/
sense fullness or pain
fullness?
pelvic splanchninc to posterior column
S2-S4
pain?
hypogastric plexus to anteriolateral column
S2-S4
reflex arc?
S2-S4
from bladder and urethra
bladder reflex arc?
sacral detrusor nucleus
-bladder fullness
urethra reflex arc?
sacral pudendal nucleus
back to voluntary sphincter (external)
parasympathetic fibers
sacral micturition centers S2-S4 (pelvic nerve)
-stimulate detrusor muscle
inhibits contraction of internal sphincter
tries to push fluid out of bladder
sympathetic fibers
hypogastric nerve
inhibits detrusor constriction
constricts internal sphincter
somatic fibers
voluntary - pudendal nerve
constrict external sphincter
hypogastric nerve
sympathetic T10-L2
pelvic nerve
parasympathetic S2-S4
pudendal nerve
voluntary somatic fibers S2-S4
barringtons center
pontine micturition center
-locus ceruleus of pons
descending impulses opposing PS outflow
coordinates activity of bladder and urinary sphincter
bladder fills to certain point and overcomes control
movement of urine in urinary tract?
peristalsis
ureters have PS and S fibers
PS stimulation increases peristalsis
-increased urine delivery to bladder
S stimulation does opposite
basal cystometrogram
volume versus pressure graph
not large increase in pressure because of bladder elasticity
micturition contraction around 200 mL volume
micturition contractions
begin around 200 mL volume
-
as radius increases?
wall tension increases
T = P x r / 2
activates the bladder stretch activated
- afferent to micturition center
- activates PS
higher center in brainstem - can suppress PS impulses up to certain point
around 400 mL
no more inhibition of PS impulses
PS stimulates bladder contraction and inhibits internal sphincter
after urine enter posterior urethra?
sensory impulses inhibit somatic nerve
-relaxes external sphincter
bladder falls in on itself pushing the urine out
sacral micturition center
in spinal cord
when can’t hold any longer
urine in posterior urethra
atonic bladder
aka flaccid neuropathic bladder
destruction of sensory input from baldder to sacral cord
-diabetes, crush injury, syphilis, MS
stretch info no longer transmitted
-no more contractions
fills to capacity (overflow incontinence)
-distended and thin walled
denervated bladder
aka hypertrophic areflexic bladder
destruction of both afferent and efferent fibers between bladder and cord
initial detrusor contraction ceases, flaccid bladder, distended
later, detrusor regains spontaneous activity
- bladder shrinks
- muscle wall hypertrophies
automatic bladder
aka spastic neuropathic bladder
damage above sacral region
-no longer have brain communication
acute - spinal shock, suppress micturition reflex
-leads to flaccid bladder
reflex gradually recovers and becomes exaggerated
-results in spasticity (control by brain is lost)
uninhibited neurogenic bladder
aka autonomic dysreflexia
destruction of tracts carrying inhibitory impulses from brain
facilitatory inputs in tact, micturition center continually stimulated
micturition activated by small amounts of urine
detrusor hypertrophies
bladder capacity reduced
urinary tract infection
bladder and urethral irritation
uninhibited contraction of detrusor muscle with facilitation of micturition reflex
urinary frequency and leakage
