Flashcards in Normal Bladder Function Deck (13):
Note From Sweaty
In simplifying the slides for urinary incontinence it would appear that I eliminated an important fact regarding Mirabegron activity. Mirabegron is a beta-3 adrenergic agonist which increases bladder capacity by relaxing the detrusor smooth muscle during the storage phase of the urinary bladder fill-void cycle. It would not be used to treat urge urinary incontinence, urgency, and urinary frequency. The alpha agonists, such as phenylephrine would be used to treat stress incontinence by producing a more profound constriction of the urethral smooth muscle.
What type of muscle is found in the internal and external urinary sphincter?
Internal = Smooth Muscle
External = Striated Muscle
Describe the filling and voiding phase of the bladder?
• Low pressure at high pressure resistance of outlet
• Low Outlet resistance and sustain detrussor contraction
What source of innervation is acting on the bladder during the filling phase. Explain how this works?
• active in relaxation of the Detrussor
• active in contraction of the internal urethral sphincter
• Nicotinic receptor that contracts external urethral sphincter
What source of innervation is acting on the bladder during the voiding phase?
1. MECHANOSENSORS - detect filling and send signal to pontine micturation center in the brain
TURN OFF SYMPATHETICS:
2. Micturation Center - sends signals telling the spinal cord to inhibit pudendal nn. = EXTERNAL SPHINCTER RELAXATION
3. Micturation Center - inhibits Hypogastric n. => INTERNAL SPINCTER RELAXATION
TURN ON PARASYPATHETICS:
4. Pelvic Splachnic nerves are what carries the signal for DETRUSSOR CONTRACTION
5. Voluntary modifications to this signaling are made in CNS
–voiding 8 or more times during waking hours
–uncontrolled leakage of urine, which can be continuous or intermittent.
–sudden and unexpected experience of an immediate need to void.
–awakening to void at night
–difficulty in the initiation of voiding
–the application of abdominal pressure (Valsalva maneuver) to initiate and maintain voiding
–observed ejection of urine with a weak force