Control of Mitcurition Flashcards
Describe the innervation of the urinary bladder, where in the spinal chord so they come from ?
(4)
- Sensory nerve in the detrusor muscle ( recognises stretch and feeds back)
- Parasympathetic pelvic nerve ( bladder stretch) S2-4
- Sympathetic hypogastric nerves (internal sphincter pressure , stretch)-T11-L2
- Somantic puedendal nerves = external sphincter nerves S2-4
Describe the mitcuration reflex (3)
when the bladder is FULL
Parasympathetic Pelvic nerve fires vvv fast signals to sacral region of the spinal cord –>Pons micturition centre:
1) Inhibition of the sympathetic hypogastric nerve which causes relaxation of the detrusor muscle, relaxation of the internal sphincter
2) Parasympathetic Pelvic nerve stimulation causes contraction of the detrusor muscle
3) Inhibition of the puedendal nerve = no contraction of the external sphincter = voiding reflex and we pee
what do the sympathetic nerves do in the bladder
- where do they act
Sympathetic hypogastric nerve acts on :
1) B3 receptor on detrusor muscle to cause RELAXATION ( holds in urine)
2)A1 receptor on the internal sphincter to cause internal sphincter contraction = holds urine in
HOLDS URINE IN = FILLING
Identify and describe the 4 abnormalities of micturition
1) Urge incontinence -frequencey and urgency
2) Stress incontinence - bladder leaks when laughing or sneezing
3) Atonic , over flowing bladder = large bladder that doesn’t empty
4) Neurogenic incontinence = involuntary micturition , over flowing or no filling
Receptors of the bladder
3 efferent nerve fibres:
1) Pelvic parasympathetic nerve =M3 nicotinic receptor on detrusor muscle = causes contraction + urine release
2) somatic puedendal nerve –>Alpha one receptor on the external sphincter , normally causes contraction of sphincter = no urine released
3) Sympathetic Hypogastric nerve = B3 receptor on detrusor muscle
- Alpha 1 internal sphincter = holds in urine contraction
4) receptor on the External sphincter =nicotinic receptor
What is overflow incontinence
1)large dilated bladder that doesn’t empty
can be due to :
- prostate cancer
- Sensory nerve damage during child birth ( no signal , so how will they know when to empty it )
Treatment :
1) M3 agonist Bethanechol ( will cause the contraction of detrusor muscle )
- catheterisation or prostate removal
What is stress incontinence
what is it ?
symptoms ?
treatments ?
1) coughing, sneezing and excersizing causes leakage or urine
- weak pelvic floor muscles mean External sphincter doesn’t work
( hence is relaxed causing leakage )
Treatments :
- bladder training , stopping mid flow
- Electrical stimulation
- Lose weight
- decrease the fluids especially: caffeinated , carbonated beverages , alcohol and citrus fruits .
- Surgery to fit external sphincter
What is urge incontinence ?
- causes
- risk factors
- treatments
1) over active bladder , frequency and urgency is increased
Causes:
1-oversensitivty due to UTI
2-Over stimulation of bladder detrusor muscle
3-Risk factors: obesity , caffeine , constipation ,poorly controlled diabetes
Treatments:
- drink more water
- decrease caffein , citrus fruit
- bladder training to recognise when its full
- Botulinum = reduces ACH release
- Anti muscarinics ( M3 antagonists= stops contraction of detrusor muscle)
- NSAIDS
What is the neurogenic bladder dysfunction ?
- causes
- treaments
due to spinal cord injury ( childbirth or severance )
results in:
- no control of External sphincter
-No voluntary control of micturition reflex
-Detrusor = overactive
Treatments:
- catheterisation
- Credes manoeuvre = pressure on abdomen bellow navel
- Improve filling with chemicals :
1) muscarinic receptor antagonists
2) Botox to reduce Ach in detrusor
3) Desensitisation of ICCs , sensory inputs with capsaicin
-electrical stimulation
What do the parasympathetic nerves do in the bladder
1) Pelvic nerve binds to the M3 receptor on the detrusor muscle= detrusor contraction ( urine is releases )
What does the somatic nerve do in the bladder ?
1)Puedendal nerve causes nicotinic receptor on the external sphincter to contract ( urine retention )
Anatomy of the bladder
Kidney –>Ureter->Bladder with detrusor muscle –>Internal sphincter –>prostate in men–>External sphincter –>urethera –> gonads
what are interstitial cells of cajal and how do they help micturition ?
(2)
In the gastrointestinal tract, interstitial cells of Cajal (ICCs) act as pacemaker cells to generate slow wave activity.
Interstitial cells that resemble ICCs in the gastrointestinal tract have been identified by their morphological characteristics in the bladder. KIT is used as an identification marker of ICCs.
what happens neurologically when we have to allow filling of urine
1) hypogastric nerve , parasympathetic nerve = inhibited M3
2) Sympathetic nerve = stimulated B3= relaxation of detrusor muscle Alpha 1 receptor = internal sphincters contract
3) puodendal nerve = nicotinic receptor on external sphincter contracts !
