UROLOGY - NEUROGENIC BLADDER Flashcards
Where do the ureters enter the bladder?
At the trigone
What 3 nerves innervate the bladdeR?
Hypogastric
Pelvic
Pudendal
Whats the function of the pelvic nerve in bladder innervatiom?
Parasympathetic nerve S2-S4 act via ACh on M3 receptors on detrusor muscle which causes contraction
= emptying of bladder
Also… Sensory fibres detect stretch in bladder walls as it fills (this is the afferent pelvic nerve)
Whats the function of the Hypogastric nerves in bladder innervatiom?
Sympathetic fibres (thoracic-lumbar region) releases noradrenaline. It binds to beta 3 receptor on detrusor muscle to cause relaxation
It binds to alpha 1 receptor on internal urethral sphincter to cause contraction
= responsible for urine retention
Whats the function of the pudendal nerves in bladder innervatiom?
Somatic nerve
Releases ACh and acts on nicotinic receptor on external urethral sphincter
= contraction of external sphincter
(Trying to hold in urine)
Outline the process of micturition
Full bladder causes stretching of detrusor muscle. Afferent pelvic nerve detects stretch and increases firing of fast signals to the sacral region of spinal cord.
This causes a neurone to go to the pontine micturition centre. This stimulates neurones here and these do a few things:
- Inhibition of Hypogastric sympathetic nerve = no relaxation of detrusor and no contraction of Internal sphincter
- stimulates pelvic efferent nerves = contraction of detrusor muscle
- inhibits pudendal nerve = no contraction of external sphincter
Whats the epithelium in the bladder?
Transitional epithelium with umbrella cells
How much urine can a bladder hold?
750ml
Bit less in women because the uterus takes up space
Why can diabetes mellitus cause overflow incontinence?
The glycation damages sensory nerve fibres of the bladder wall, pelvic nerve and dorsal nerve roots.
This interferes with the initial stretch signal that gets sent out as the bladder fills
Why can syphilis cause overflow incontinence?
This infection can lead to tabes dorsalis (slow degeneration of neural tracts primarily in dorsal root ganglia of spinal cord)
Why can herpes cause overflow incontinence?
Herpes zoster infection involving sacral demratomes can lead to the Virus staying in dorsal nerve roots for months-years. This can disrupt sensory fibres so sensory information isn’t received
Why can trauma to the sacral region of spinal cord cause overflow incontinence?
Micturition reflex pathway is interrupted
What is spinal shock?
When the spinal coed is damaged and there’s an immediate response where all the reflexes below the level of injury are suppressed
This can last hours - weeks
Causes detrusor hyporeflexia which leads to overflow incontinence
When this resides you then get detrusor hyperreflexia and urge incontinence
Why can multiple sclerosis cause urge incontinence?
Prevention of inhibitory signals from brain reaching the micturition reflex pathway = detrusor hyperreflexia and urge incontinence
How can an acute injury like a stroke affect continence?
Initially shock phase of destructor hyporeflexia and overflow incontinence followed by destructor hyperreflexia and urge incontinence
