Control of Micturition Flashcards
designing a urine disposal system - what is needed?
- collection
- storage
- disposal
- control override
- emergency/failsafe
what is used as the collection of urine?
kidney to ureter to bladder
what is used for storage of urine?
bladder
what is used for the disposal of urine?
bladder to urethra
what is used for the control override for the urine disposal system?
automatic (autonomic), manual (somatic)
what is used for the emergency/failsafe for urine disposal?
ureterorenal reflex, vesicoureteric ‘reflex’
how is urine collected?
blood filtered in kidneys
ureters transport urine from calices to bladder
occurs via smooth muscle contraction; peristalsis
autonomic innervation; parasympathetic nervous system
describe the ureterorenal reflex:
ureters are well supplied with pain nerve fibres which can cause an intense reflex constriction w/ severe pain whenever the ureters become blocked
Pain impulses from the ureters induce vasoconstriction of renal arterioles, decreasing GFR
Important in preventing excessive flow of fluid into the renal pelvis of the kidney with the blocked ureter
Sympathetic reflex
what are the layers of the bladder wall?
transitional epithelium (urothelium)
lamina propria
submucosa
detrusor muscle - 3 layers
adventitia
describe the transitional epithelium lining:
stretch - allowed by rugae
stretch - allowed by umbrella cells
reduce back-pressure on the kidney
where does the ureter enter?
proximal entry through detrusor muscle in bladder trigone
describe the oblique path of ureter against bladder wall:
creates valve-like entry
reduce urinary reflux and damage
where do ureters enter bladder?
they enter bladder with oblique pathway through detrusor muscle
contraction of the detrusor muscle does what?
keeps ureter compressed
describe the vesicoureteric ‘reflex’:
short passage through bladder wall
bladder contraction in micturition may not always occlude ureters
Reflux of urine (vesicoureteric reflux)
results in renal damage
involuntary control of the bladder?
detrusor muscle
internal sphincter
controlled by autonomic nervous system
Describe the voluntary control of the bladder:
external sphincter
controlled by the somatic nervous system
bladder fills up but animal cannot urinate can lead to?
backing of urine into kidneys leading to renal failure
pain
need to drop pressure in bladder
hypogastric function - what relaxes/contracts?
bladder is relaxed
detrusor muscle is relaxed under influence of the hypogastric nerve
nervous input to the bladder and proximal urethra - occurs more caudally?
bladder is fine
