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The Urinary System: Urinary Retention Essay

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Urination is controlled by a complex central nervous system mechanism that coordinates urine storage and release by the regulation of smooth muscle in the bladder and urethra. Bladder storage, emptying and coordinated urinary sphincter activity , are controlled by the sympathetic, parasympathetic, and somatic nervous systems.
Parasympathetic nerves in the spinal cord (S2-S4) act to contract the bladder and relax the urethra through the release of acetylcholine, which excites smooth muscle muscarinic receptors (17). This causes urination through detrusor contraction. Postganglionic sympathetic neurons (T11- L2) . release noradrenaline causing bladder base contractions and relaxation of the bladder body, mediated by acetylcholine on …show more content…

M2 muscarinic receptor subtypes have also shown in mouse studies to be involved in enhancing M3 stimulation and inhibiting cyclic adenosine monophosphate levels in the bladder that cause bladder relaxation therefore also encouraging urination (18, 19, 20). Therefore medications that antagonise muscarinic receptors are effective in the management of urinary incontinence such as Oxybutynin and Tolterodine. It however also means non-selective anticholinergic medications used can increase urinary retention as a potential side effect.
Serotoninergic mechanisms seem to also be involved in micturition as shown by the use of Duloxetine a combined noradrenaline and serotonin reuptake inhibitor (NSRI) in the treatment of stress and urge incontinence. Therefore other NSRIs may act increase neural activity in similar ways to the bladder in those who do not suffer incontinence causing urinary retention.
Urinary retention occurs acutely or chronically with impaired bladder emptying through the urethra resulting in a post-voidal residual volume. There are multiple aetiologies including nerve damage, infections, benign prostatic hyperplasia, prostate carcinoma and iatrogenic.
Urinary retention has been identified as a side effect of multiple drugs including anaesthetics, opioids, benzodiazepines, anticholinergics, calcium channel blockers and NSAIDs (1). This is more common in the

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