A 54-year-old woman with a history of urgency and urinary incontinence comes to the clinic for review. She rs taking a number of medrcations for epilepsy and is concerned that these may lead to loss of control over bladder emptying.
Bladder emptying occurs as a result of what?
A Decreased parasympathetic nervous activity
B Decreased sympathetic nervous activrty
c Increased dopaminergic nervous acuvrty
Increased parasympathetic nervous activrty
E Increased sympathetic nervous activity
Explanation
Parasympathetic nerves originating from S2.S4 innervate visceral motor neurones in parasympathetic ganglia in or near the bladder wall. They promote bladder contraction leading to emprying Muscarinic antagonists are the marnstay of treatment of bladder hyperactivity.
i)
Decreased parasympathetic nervous activity, (Option A), is incorrect. This is responsible for hypoactive bladder and may lead to incomplete emptying.
Decreased sympathetic nervous activity, (Option B), is incorrect Sympathetic nervous system activity leads to closure of the internal urethral sphincter. Decreased activity therefore promotes sphincter relaxation but not bladder emptying where muscle contraction is required.
Increased dopaminergic nervous activrty, (Optron C), is incorrect. Although dopaminergic nervous system dysfunction may result in incontinence, it is parasympathetic nerves that have the primary role in bladder emptying.
Increased sympathetic nervous activity, (Option E), is incorrect, this promotes closure of the internal urethral sphincter.