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fowler(Neural Control) (peripheral innervation (parasympathetic (pelvic…
fowler(Neural Control)
storage and elimination of urine
bladder
outlet: sphincter, urethra, bladder neck
neural control mediated by spinal cord, brain and peripheral system
peripheral innervation
sympathetic
arises in TL region
hypogastric nerve releases noradrenaline
activates beta adrenergic receptor in bladder to relaxe the bladder
activates alpha adrenergic receptor in urethra for urethra contraction
activates alpha - and beta - receptors in bladder ganglia
parasympathetic
arises in Sacral region
pelvic nerve releases
cholinergic transmitters
main bladder excitatory mechanism. mediated by 2 receptors
M3 main
M2 also mediates
non cholinergic transmitters
ATP acts on P2X for detrusor contraction
NO inhibits urethra contraction
muscarine receptors on nerve endings
m1 enhances transmitter release
m4 suppresses transmitter release
somatic
arises in Sacral region in onuf's nucleus
innervates pelvic floor
afferent neurons which travel back along the same path as efferent pathways
bladder fullness
transmitted via pelvic and hypogastric nerve to spinal cord
inputs from urethra and bladder neck conveyed via pudendal and hypogastric nerve
composed of A delta and C fibres. A delta more active
urothelium
sensory and signaling properties
expression of various receptors
responsiveness to transmitters from afferent nerves
release of chemical mediators like ATP
thus regulate activity of adjacent nerves
could have role in generation of spontaneous contractions in bladder. Interstitial cells can also be involved in this
supraspinal and brain pathways in regulation of micturition
Brain
serotonergic neurons
noradrenergic neurons
PMC
receives inputs from PAG and from other centres of brain for initiation of micturition
PAG
regulation of bladder filling and voiding
filling
guarding reflex
activated by pelvic afferent nerves
organised by interneuron circuitry in spinal cord
some input from PSC
spinobulbospinal voidal reflex functions as an on/off switch
during bladder filling and till certain volume of bladder parasympathetic remains quiet
drugs injected in PMC can change the time at which the switch happens