Bladder and Micturation Flashcards
how can you describe the layers of the bladder?
outer peritoneum, layer of smooth muscle and CT (detrusor muscle), inner mucosal layer
How are the urethral sphincters made in men vs. women?
women = smooth muscle fibers in the bladder neck that make up the sphincter
men = smooth mm in bladder neck makes a ring and works with prostate
In the female, what is responsible for continence?
the intrinsic sphincter, comprised of bladder neck muscle fibers and the mid-urethral complex
Is there a difference in what makes a male/female continent?
Yes, the prostate and the bladder work together to make the instrinsic sphincter in the male
*intrinsic sphincter is responsible for continence in both sexes, but the makeup of the sphincter is slightly different
What does the parasympathetic nervous system innervate in the lower urinary tract?
PNS = detrusor muscle - activation results in detrusor muscle contraction and micturation
What does the sympathetic nervous system innervate in the lower urinary tract?
SNS = inhibits detrusor mm contraction, increases tension in the smooth mm of the bladder neck and proximal urethra PREVENTING MICTURATION UNTILL PARASYMP INNERVATION
From where does the motor innervation of the lower urinary tract arise?
S2 - S4 of the spinal cord
*both control voluntary mm of bladder, pelvic floor and urethral sphincter AND carries stretch receptor data from spinal cord to pons
The hypogastric nerves are part of what branch?
Hypogastric nerves = sympathetic branch. arise from T10-L2
The Pelvic nerves are part of what branch of the nervous system?
Pelvic = Parasympathetic (p = p)
* come from sacral plexus
The pudendal nerves carry what fibers?
Lower motor neurons make up the pudendal nerves
*innervate the muscles of the pelvic floor and the external urethral sphincter
Diseases such as dementia, stroke, parkinsonism all affect what part of the brain and therefore mess with what part of the lower urinary tract?
These diseases inhibit cortical function (mess with the cortex in the brain), which will stop the voluntary inhibition of micturation
*THESE DISEASES RESULT IN INCONTINENCE
what do disturbances in the storage function result in?
frequency, urgency, urge incontinence
*storage phase = interrelated and coordinated neural and neuromuscular responses allowing bladder to adapt to increasing volume with little increase in pressure
What is the afferent response of the storage reflex and what might cause dysfunction?
- afferent activity is generated by filling of the bladder
- sensory fibers in the pelvic nerve enter the sacral cord via the sacral DRG
- DYSFUNCTION of the unmyelinated C fiber afferents during spinal cord injury OR MS will lead to reorginization of reflex
What is the efferent response of the storage reflex and what might cause dysfunction?
- efferent responses to bladder filling are controlled at supraspinal levels by activating somatic (pudendal) motor neurons in anterior horn of the sacral spinal cord
- efferent responses are associated with inhibition of the detrusor motor neuron combined somehow with cortical inhibition???
- DYSFUNCTION - can result from stroke, frontal lobe lesions, MS, SCI can all impair inhibitor input resulting in detrusor overactivity
- detrusor activity means micturation
Disturbances in the micturation cycle and thus voiding result in what symptoms?
hesitancy, weak stream, incomplete bladder emptying, retention
What are the 5 steps of the micturation cycle?
1) increase in bladder wall tension
2) afferent input overcomes the pontine micturation center threshold and provides cortical egress making micturation begin
3) pudendal nerve activity ceases, external sphincter/pelvic floor relaxes, detrusor neurons are freed and discharge
4) proximal urethra opens
5) bladder immediately contracts
What nerve impulses are occurring when the bladder is contracting?
when voiding occurs, sympathetic and somatic tone decrease and parasympathetic mediated impulses cause the bladder to contract
What kind of neurons make up the pelvic nerve afferents and what do they do?
pelvic nerve afferents, which monitor the volume of the bladder and the amplitude of bladder contractions consist of small myelinated A-delta fibers and unmyelinated C-fibers
Somatic pudendal nerves have what effect on the bladder and the urethra sphincter?
somatic pudendal nerves inhibit bladder contraction and stimulate the urethra to contract (they inhibit micturation)