Micturition Flashcards
What is micturition?
urination
continence
to hold back
Which part of the brain controls voluntary micturition?
The cerebral cortex and the pontine micturition center.
What type of muscle is the detrusor muscle?
It is smooth muscle.
What is the function of the detrusor muscle?
It contracts to expel urine from the bladder during micturition.
Which nerves are involved in the micturition reflex?
Pelvic nerves (parasympathetic), hypogastric nerves (sympathetic), and pudendal nerve (somatic).
What does the parasympathetic nervous system do during micturition?
It stimulates the detrusor muscle to contract and the internal urethral sphincter to relax.
What is the role of the pudendal nerve in micturition?
It controls the external urethral sphincter, allowing voluntary control over urination.
What initiates the micturition reflex?
Stretch receptors in the bladder wall when it fills with urine.
At what volume does the bladder typically trigger the urge to urinate?
Around 150–200 mL.
What happens to the internal urethral sphincter during micturition?
It relaxes to allow urine to pass from the bladder into the urethra.
What is the internal urethral sphincter made of?
Smooth muscle, under involuntary (autonomic) control.
What is the external urethral sphincter made of?
Skeletal muscle, under voluntary (somatic) control.
Which neurotransmitter is released by the parasympathetic nerves during micturition?
Acetylcholine (ACh).
What receptors are activated by acetylcholine in the bladder during micturition?
Muscarinic receptors (mainly M3) on the detrusor muscle.
What is urinary retention?
The inability to completely empty the bladder.
What is incontinence?
The involuntary leakage of urine.
What part of the spinal cord is involved in the micturition reflex?
The sacral spinal cord (S2–S4 segments).
What effect does the sympathetic nervous system have on the bladder?
It relaxes the detrusor muscle and contracts the internal urethral sphincter to store urine.
What is the difference between storage and voiding phases in bladder control?
Storage: bladder fills, detrusor relaxes, sphincters contract.
Voiding: detrusor contracts, sphincters relax.
What is the function of the pontine micturition center (PMC)?
It coordinates the switch between storage and voiding phases of micturition.
What is a neurogenic bladder?
A bladder dysfunction caused by neurological damage, affecting micturition control.
What is the guarding reflex?
A spinal reflex that increases sphincter tone to prevent urination when bladder fills.
How do infants urinate if they lack voluntary control?
They rely solely on the micturition reflex until higher brain centers develop control.
How does aging affect micturition?
It may lead to reduced bladder capacity, incomplete emptying, or incontinence.
What are the two main phases of micturition?
The storage (continence) phase and the voiding phase.
Which nervous system controls the storage phase of micturition?
The sympathetic nervous system.
What is the role of the pontine continence center?
It coordinates the actions of the urinary sphincters and the bladder during the storage phase
At approximately what bladder volume do afferent nerves signal the need to void?
Around 400 mL of filling
What is the typical urinary flow rate in women during the voiding phase?
25–30 mL/s.
What is the function of the pontine micturition center during the voiding phase?
It excites sacral preganglionic neurons to initiate urination.
How does the sympathetic nervous system facilitate urine storage?
By relaxing the detrusor muscle and contracting the internal urethral sphincter.
What is the role of the somatic nervous system in micturition?
It controls the external urethral sphincter, allowing voluntary control over urination.
What structures make up the lower urinary tract?
The bladder and urethra.
What are the two primary functions of the lower urinary tract?
Storage of urine and efficient emptying.
What symptoms can result from disturbance in lower urinary tract function?
Frequency, urgency, incontinence, voiding symptoms, and urinary retention.
What are the three histological layers of the urinary bladder?
Outer adventitial connective tissue, middle smooth muscle (detrusor), and innermost transitional epithelium.
What controls voiding (micturition)?
The pontine micturition centre in the brain.
What is urodynamics?
The study of the process of micturition.
What is the normal bladder capacity?
Approximately 500 mL.
What are normal voiding pressures and flow rates for males?
40-50 cm H2O and 30-40 mL/s.
What are normal voiding pressures and flow rates for females?
30-40 cm H2O and 40-50 mL/s.
What does cystometry measure?
Pressure-volume relationships of the bladder.
What is assessed in cystometry?
Bladder compliance, sensation, stability, and capacity.
What does LUTS stand for?
Lower Urinary Tract Symptoms.
What is BPH?
Benign Prostatic Hyperplasia (histological diagnosis).
What is BPE?
Benign Prostatic Enlargement.
What is BOO?
Bladder Outflow Obstruction.
What are storage symptoms?
Urgency, frequency, nocturia, incontinence.
What are voiding symptoms?
Hesitancy, poor stream, straining, terminal dribbling, incomplete emptying.
What are post-micturition symptoms?
Dribbling.
What are common causes of voiding difficulty in men?
Increased outflow resistance (e.g., BPH, stricture), and detrusor muscle failure.
What are effects of obstruction?
Development of LUTS, urinary retention.
What is acute urinary retention?
Painful inability to void, relieved by catheter drainage.
How much urine is typical in acute retention?
500-800 mL.
What are causes of BOO in women?
Urethral obstruction and neurological disorders.
What are non-curative treatments for BOO in women?
Self-catheterisation, indwelling catheter, Mitrofanoff stoma.
What medications are used to treat BOO?
Alpha-blockers, 5-alpha-reductase inhibitors.
What is detrusor failure?
Underactive bladder, can lead to chronic retention with overflow.
What are causes of chronic retention?
Prostate obstruction, urethral stricture, LMN lesions.
What is the ICS definition of urinary incontinence?
The complaint of any involuntary loss of urine.
What is stress incontinence?
Leakage due to weakness of the urinary outlet.
What is urge incontinence?
Leakage due to failure of the bladder to store urine from high pressure.
What is mixed incontinence?
A combination of stress and urge incontinence.
What is overflow incontinence?
Due to chronic retention with an overfull bladder.
What are common types of incontinence in men?
Overactive bladder, neuropathic bladder, post-prostatectomy, overflow.
What are risk factors for urinary incontinence?
Pregnancy, childbirth, menopause, obesity, constipation, chronic cough.
What are treatments for female stress incontinence?
Behavioural therapy, pelvic floor exercises, pharmacologic agents, surgery.
Name some pharmacologic agents for female SUI.
Alpha-agonists, estrogens, TCAs, duloxetine.
What are common surgical treatments for female SUI?
TVT, TOT, midurethral slings, bladder neck suspension, urethral injectables.
What are bulking agents used for?
To increase urethral resistance by mucosal coaptation.
What is overactive bladder?
Frequency, urgency, urge incontinence; often stress incontinence too.
What are treatments for overactive bladder?
Behavioural therapy, anticholinergics, mirabegron, Botox, neuromodulation.
What is InterStim Therapy?
A neuromodulation system for treating overactive bladder symptoms.
What is PTNS?
Percutaneous Tibial Nerve Stimulation, a treatment for OAB.
What are QoL issues associated with UI?
Distress, embarrassment, loss of control, depression, falls in elderly.
What are NICE recommendations related to incontinence treatment?
Supports use of neuromodulation techniques like PTNS for UI and FI.
