Lower Urinary Tract Flashcards
describe the innervation of the bladder and the urethra, and nervous system factors present in each area and their respective effects
afferent innervation:
stretch or pain receptors in the bladder wall send afferent signals along the pelvic, hypogastric, or pudendal nerves to the spinal cord then to the brainstem (pontine micturition center) and then to the forebrain
efferent innervation:
1. hypogastric nerve: sympathetic nervous system; beta and alpha receptors
2. pelvic nerve: parasympathetic nervous system; acetylcholine muscarinic receptors
3. pudendal nerve: somatic nervous system; acetylcholine nicotinic receptors
describe the role of the somatic, sympathetic, and parasympathetic nervous system in control of micturition and storage; describe the process of urine storage and elimination by the lower urinary tract (basically the same LO, just talk about the nerves)
storage:
1. sympathetic stimulation of hypogastric nerve: to beta receptors causes detrusor to relax; to alpha receptors causes internal sphincter to contract
2. parasympathetic transmission is inhibited
3. somatic nervous system: external sphincter and pelvic floor are relaxed
micturition (if appropriate time to pee):
1. parasympathetic: pelvic nerve causes detrusor to contract
2. sympathetic: hypogastric inhibited
3. somatic: voluntary control via pudendal nerve relaxes external sphincter
list the lower urinary tract barriers to prevent infection
main local defense: unidirectional flow physically removes bacteria by ureteral peristalsis and the ureterovesicular junction (forms a valve when expanded to prevent retrograde flow)
but additional barriers include:
1. urethral length (males have advantage because they have longer urethra)
2. mucosal barriers: mucus and antimicrobial compounds
3. urine characteristics not nice to bacteria: high osmolar, high urea, organic acids
4. tamm-horsfall protein: competitive inhibition of bacterial binding to epithelium
