13 Neural Control of Micturition Flashcards
Neural control of micturition consists of the storage phase and the voiding phase. Which of these is (normally) the dominant reflex?
Storage reflex
What is the function of the internal urethral sphincter?
Prevent retrograde ejaculation (not well developed in women)
Explain how retrograde ejaculation may occur.
When Internal Urethral Sphincter affected
Eg in diabetes - neural control of IUS affected
Why are babies unable to control when they urinate?
Pathways not yet myelinated
Babies only have voiding reflex arc- involuntary
If someone get a lesion to their spinal cord at S1 spinal level- what will happen to their neural control of micturition? Why?
Voiding reflex will be overactive
Majority of influence on efferent pathway (parasympathetic neurones) = negative influence
Without negative influence, voiding reflex= overactive
How does the M centre connect to the L centre?
M centre inhibits L center and sympathtetics - causing sphincters to relax
If someone acquires a lesion to the spinal cord around the S3 level, what will be the effects on neural control of micturition?
Perpetual storage
Once bladder full- urine will trickle out
Parasympathetics destroyed
Sympathetics still acting
(like cauda equina)
Outline the mechanism of action that drugs given to treat an overactive bladder will have:
ß3 agonists given- inhibit contraction of bladder via sympathetics
Explain why one of the side effects of giving a patient anti-muscarinics can result in urinary retention.
Muscarinics within parasympathetics stimulate contraction of bladdr
So inhibiting M3 receptors causes relaxation of bladder
Explain the mechanism of action of a drug given to men to facilitate urination if they have urinary tract symptoms.
a1 antagonists- causing relaxation of IUS - facilitate urination
Talk through neural control of micturition using following diagram:
