Micturation

Question 1

process of micturition

Answer 1

Filling of the urinary bladder
Increase in intravesical pressure
Stretching of the bladder wall
Activation of mechanoreceptors
Sensory information is sent to the spinal cord through pelvic splanchnic nerves
Information is relayed to the pontine micturition center (PMC), a collection of neuronal cell bodies located in the pons that coordinate the process of micturition
Information is integrated in higher (cortical) brain centers
Perception of bladder fullness
Urination if feasible: activation of the PMC → stimulation of parasympathetic fibers and inhibition of somatic pudendal nerve fibers → contraction of the detrusor muscle and relaxation of the external urethral sphincter → micturition
Urination is unfeasible: cortical inhibition of the PMC → no stimulation of parasympathetic fibers or inhibition of somatic pudendal nerve fibers → no contraction of the detrusor muscle or relaxation of the external urethral sphincter → no micturition