Urology Flashcards
Function of the Urinary Tract
To collect urine produced continuously by the kidneys
To store collected urine safely
To expel urine when socially acceptable
Anatomy of kidney
Retroperitoneal organs
Lie between T11 – L3
Blood supply from renal artery direct from aorta at L1 level
How many nephrons does each kidney contain
1 million nephrons
How much urine does each kidney produce a day
1-1.5L of urine per day
Ureters- Anatomy
25cm – 30cm
Retroperitoneal organs
Run over psoas muscle, cross the iliac vessels at the pelvic brim and insert into trigone of bladder
Ureters function
Transport urine from the kidney to the bladder via peristalsis
What is preventing the reflex of urine
a valvular mechanism at the vesicoureteric junction
Nervous Control of the Bladder and Sphincter- 4 nerve
Parasympathetic Nerve (pelvic nerve)
Sympathetic Nerves (hypogastric plexus)
Somatic Nerve (pudendal nerve)
Afferent pelvic nerve
Nervous Control of the Bladder and Sphincter- Parasympathetic Nerve (pelvic nerve)
- S2-S4
- acetylcholine neurotransmitter
- involuntary control
Nervous Control of the Bladder and Sphincter- Sympathetic Nerves (hypogastric plexus)
T11 – L2
noradrenaline neurotransmitter
involuntary control
Nervous Control of the Bladder and Sphincter- Somatic Nerve (pudendal nerve)
S2-S4
“Onuf’s nucleus”
acetylcholine neurotransmitter
Nervous Control of the Bladder and Sphincter- Afferent pelvic nerve
Sensory nerve
signals from detrusor muscle
Neural Control- Onuf’s Nucleus
Responsible for guarding reflex
Neural Control- Pontine Micturition Centre/Periaqueductal Grey
Responsible for Co-ordination of voiding
Neural Control- Cortex
Responsible for voluntary control
Neural Control- Sacral Micturition Centre
Responsible for Micturition reflex
Storage Phase
Bladder fills continuously
As the volume in the bladder increases the pressure remains low due to “receptive relaxation” and detrusor muscle compliance
Filling Phase
At lower volumes the afferent pelvic nerve sends slow firing signals to the pons via the spinal cord
Filling phase- nerves
-Sympathetic nerve (hypogastric plexus) stimulation maintains detrusor muscle relaxation
-Somatic (Pudendal) nerve stimulation maintains urethral contraction
Voiding Phase – Micturition Reflex
Autonomic spinal reflex
Higher volumes stimulate the afferent pelvic nerve to send fast signals to the sacral micturition centre in the sacral spinal cord
Voiding Phase – Micturition Reflex- nerves
Pelvic parasympathetic nerve is stimulated and the detrusor muscle contracts
Pudendal nerve is inhibited and the external sphincter relaxes
Guarding Reflex
Voluntary control of micturition
Guarding Reflex
Afferent signals from the pelvic nerve are received by the PMC/PAG and transmitted to higher cortical centres
If voiding is inappropriate the guarding reflex occurs
Sympathetic (hypogastric) nerve stimulation results in detrusor relaxation
Pudendal nerve stimulation results in contraction of the external urethral sphincter
Storage summary
Receptive Relaxation
Detrusor relaxation (sympathetic stimulation T11-L2)
External Urethral Sphincter contracted (pudendal stimulation S2-4)