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1. MICTURATION REFLEX
Dr. Suman Mukherjee
1ST YEAR M.D.S.
V.S.D.C.H.

2. MICTURATION
The process by which the urinary bladder empties when it becomes
filled.

3. TRANSPORT OF URINE FROM THE KIDNEY
THROUGH URETERS INTO BLADDER.
Kidneys
–Calyces
• Ureters
• Bladder
• Vesicoureteral Reflux
• Pain and ureterorenal reflex

4. FILLING OF THE BLADDER

5. The ureters pass obliquely through the detrusor muscle and it passes
little further underneath the bladder mucosa. This oblique passage tends
to keep the ureters closed except during peristaltic waves, preventing
reflux of urine from the bladder.

6. REGULATION OF THE
BLADDER

7. MICTURATION REFLEX

8. VESICOURETERAL REFLUX
In some people, the distance that the ureter courses through the
bladder mucosa is less than normal, so that contraction of the
bladder during micturition does not always lead to complete
occlusion of the ureter. As a result some of the urine in the
bladder is propelled backward into the ureter. This is called
‘Vesicoureteral reflux’.

9. URETERORENAL REFLEX
The ureters are well supplied with pain nerve fibers. When a
ureter is blocked e.g. by a ureteral stone, there will be intense
reflex constriction which is associated with very severe pain.
These pain impulses cause a sympathetic reflex back to the kidney
to constrict the renal arterioles, thereby decreasing urinary
output from that kidney. This effect is known as ‘Ureterorenal
reflex’.

10. CYSTOMETOGRAM

11. Abnormalities of
micturition
reflex:

12. ATONIC BLADDER(FLACCID
NEUROPATHIC)
Destruction of sensory inputs form bladder to sacral cord (diabetes,
crash injury, syphilis, MS)
Stretch information is no longer transmitted and bladder contractions
are no longer initiated
Bladder becomes flaccid and filtered to capacity ("overflow
incontinence"); eventually becomes distended and thin-walled

13. AUTOMATIC BLADDER (SPASTIC
NEUROGENIC BLADDER)
Injury or severing of spinal cord above sacral region (cuts off
communication with brain)
"spinal shock" temporarily suppresses micturition reflex which leads to
flaccid neuropathic bladder (acute phase)
Eventually, micturition reflex can gradually recover and become
exaggerated resulting in spasticity (voluntary control is lost); in other
words, there is voiding that can't be overridden

14. DENERVATED (HYPERTROPHIC
AREFLEXIC) BLADDER
Destruction of both afferent and efferent fibers between bladder and
cord
Detrusor muscle contractions cease; bladder becomes flaccid and
distended; bladder does not empty reflexively and always remains full
Eventually, detrusor regains spontaneous activity; bladder shrinks due
to ineffective contractions and muscle hypertrophies

15. UNINHIBITED NEUROGENIC BLADDER
(AUTONOMIC DYSREFLEXIA)
Destruction of tracts carrying inhibitory impulses from brain
(can't inhibit voiding when bladder is full)
Facilitatory inputs remain intact; micturition center is continually
stimulated; micturition is activated by small amounts of urine
Eventually, detrusor hypertrophies; bladder capacity is reduced;
as muscle wall gets thicker, bladder can hold less volume.