8.1 The Neural Control of Micturition Flashcards
What is micturition?
Want to pass urine
What is the main muscle of the bladder called?
Detrusor muscle
What 3 points make up the trigone?
2 ureteric orifices and internal urethral orifice
Which way do the 3 layers of fibres lie in the detrusor muscle?
Inner and outer layers lie longitudinally and the middle layer is circular
What innervates the external urethral sphincter? What receptor does it go to?
Pudendal nerve- using ACh
(somatic)
Nicotinic receptor
What nerve provides sympathetic innervation to the bladder? What receptor does it go to?
Hypogastric nerve
B3 and a1 receptor
What nerve provides parasympathetic innervation to the bladder? What receptor does it go to?
Pelvic nerve
M3 receptor
What are the 2 phases of micturation?
Continence phase
Voiding phase
What os the capacity of the bladder?
550ml
How is the continence phase of micturition controlled?
Pontine centre
Sympathetic nuclei
Detrusor muscle relaxes and external urethral sphincter closes
What are the pontine continence circuits?
Bilateral outputs from the Pons
What is the function of the pontine continence circuits?
Relax detrusor muscle
Increase external urethral sphincter pressure
Storage of urine
What does the somatic nervous system do in the continence phase of micturition?
Activates closure of the external urethral sphincter
What are the folds of the bladder called?
Rugae
What happens in the voiding phase of micturition?
Bladder contracts and the external sphincter relaxes resulting in the excretion of urine
