Micturition Flashcards
is micturition under autonomic or voluntary control
both
2 modes of bladder operation
storage and elimination
shape of the bladder
triangular pyramid shape
4 surfaces = superior, base (posterior), 2 inferior lateral
ureter and urethral openings
4 uncles control micturition
- detrusor muscle (wall of bladder)
- internal urethral sphincter (valve controls output of urine - autonomic NS)
- external urethral sphincter (lower voluntary control)
- bulbospogiosus muscle (penis)
full bladder capacity
500 ml
Pelvic organ
bladder dullness felt at
400 ml
is passing urine sympathetic or parasympathetic
passing out urine = parasympathetic
holding in urine sympathetic or parasympathetic
sympathetic
nerves controlling micturition
- sympathetic nerves
2a parasympathetic efferent nerves
2b sensory stretch nerves (parasympathetic afferent)
3 somatic nerves
nerves controlling micturition
- sympathetic nerves
2a parasympathetic efferent nerves
2b sensory stretch nerves (parasympathetic afferent)
3 somatic nerves
sympathetic nerves
T12-L2
contain urine
contract - internal urianry sphincter
Relax - detrusor muscle (wall)
Parasympathetic nerves
S2-S4
release urine
Contract - detrusor muscle (wall)
Relax - internal urianry sphincter (open up)
somatic nerves
control external urethral sphincter
voluntary control
tighten if holding in urine
Pontine micturition centre
Pons in the brainstem
micturition junior manager
relay station for ascending spinal bladder information and higher brain areas
what happens when bladder is full but can’t go to the toilet
- neurons are silent when bladder empty
- activated when stretch mechanoreceptors are triggered when full
- relaxes external urethral sphincter
- contracts detrusor muscles
- bathroom is full = brain inhibits Pontine micturition centre(PMC) !!