Flashcards in Renal Therapeutics IV: Urine Transport, Storage & Elimination Deck (35):
Name the 3 parts of the urinary tract
What is the micturition complex?
Nervous system which co-ordinates the process of urination
Explain the micturition reflex
Sensory fibres in the pelvic nerve sense the stretch due to bladder filling
Parasympathetic fibres control muscle contraction (bladder)
Interneurons communicate signals up to the hypothalamus. with relays into the cortex
Voluntary relaxation of the external sphincter results in urination
Explain in detail what happens as the bladder fills with urine in the micturition reflex
Stretch receptors in urinary bladder stimulate pelvic nerve
Stimulus travels from pelvic nerves and stimulates ganglionic neurons in the wall of the bladder
Post-ganglionic neuron in intramural ganglion stimulates detrusor muscle contraction
Inter-neuron relays sensation to the thalamus and delivers sensation to cerebral cortex
Voluntary relaxation of external and so internal urethral sphincters
= Urine released
List groups of people who may have problems with their micturition reflex
Older people - age-related changes in the urinary system
Why do infants have issues with their micturition reflex?
Cortico-spinal connection are not established so they lack voluntary control over urination
List 3 age-related changes to the urinary system that some older people suffer from
1. Decline in the number of functional nephrons
2. Reduced sensitivity to ADH
3. Problems with the micturition complex
List 3 problems which may affect the micturition complex
1. Sphincter muscle loses tone - leads to incontinence
2. Control of micturition can be lost due to a stroke, Alzheimer's, CNS problems affecting cerebral cortex or hypothalamus
3. In males - urinary retention may develop if enlarged prostate gland compresses the urethra and restricts urine flow
An involuntary loss of urine that enough to cause a social or hygiene concern
What is stress incontinence?
Caused by coughing, sneezing, laughing or carrying heavy weights as the normal control mechanism is weakened
Can happen when the urethra is moved out of the normal position (prolapses) after weakening of the pelvic floor muscles
What is urge incontinence?
Strong urge to pass frequent, small amounts of urine
Caused by the muscle of the bladder wall (detrusor muscle) being overactive
= It contracts to squeeze out urine before the bladder is completely full
What is mixed incontinence?
Some women may get both urge and stress incontinence
The 2 may or may not be linked
What is overflow incontinence?
When the urine held by the bladder builds up to the point where the bladder can no longer expand
Can be caused by an obstruction in the urinary tract or damage to the nerves that supply the bladder
Explain some other causes of incontinence
Medication - side effects of some drugs for high BP (prazosin, doxazosin) and muscle relaxants (diazepam)
Problems with the urinary system e.g. fistulas = abnormal openings between the ureter, urethra or bladder into the uterus or vagina
List the 4 types of incontinence
What are the 3 methods used to treat incontinence?
1. Behavioural techniques
2. Surgical treatments
3. Pharmacologic treatments
Explain the behavioural technique used to treat incontinence
Scheduled toileting (every 2-4 hours)
Frequently empty the bladder to prevent incontinence
Recommended for frail, elderly or bedridden patients who are not able to make it to the toilet
Explain the surgical option used to treat incontinence
Should be considered only after all conservative options have been exhausted
Long-term success rates = excellent
However rare complications = infection, bleeding, continued incontinence, inability to urinate
Which methods are usually used to manage stress incontinence?
Which methods are generally used to manage urge incontinence?
List 4 drugs which are used to manage urge incontinence
Oxybutynin and tolterodine
How does Duloxetine work to prevent urge incontinence?
Antimuscarinic = reduces contractions of the bladder and increase bladder activity
Can also be used to treat moderate-severe stress incontinence
How do Oxybutynin (Ditropan) and Tolterodine (Detrusitol) work to prevent urge incontinence?
They cause relaxation of smooth muscle of bladder
List 4 possible side effects of using the highlighted drugs to treat urinary incontinence
All of these drugs may show anti-cholinergic effects:
Dry mouth and eyes
Inability to urinate
What is Benign Prostate Hypertrophy?
An enlarged prostate
As the prostate gets bigger it may squeeze or partially block the urethra, causing problems with urination
What is the prostate?
The male reproductive gland which produces the fluid that carries sperm during ejaculation
It surrounds the urethra (tube which passes out of the body)
What is benign prostate hypertrophy also known as?
Benign prostate hyperplasia
List 4 symptoms of benign prostate hypertrohpy
Dribbling at the end of urination
Inability to urinate (urinary retention)
Incomplete emptying of bladder
Needing to urinate 2 or more times at night
Name 3 tests which may be performed for benign prostate hypertrophy
Digital rectal exam to feel the prostate gland
Urine flow rate
Post-void residual urine test = see how much urine is left in the bladder after urination
Name 3 types of medication which may be prescribed to treat benign prostate hypertrophy
Finasteride and dutasteride
How do alpha-1 blockers treat benign prostate hypertrophy?
Relax the muscles of the bladder, neck and prostate - allows for easier urination
Also used to treat hypertension
How do Finasteride and Dutasteride treat benign prostate hypertension?
Lower the levels of hormones produced by the prostate
Reduce size of the prostate gland
Increase urine flow rate
Decrease symptoms of BPH
Why may antibiotics be prescribed to treat benign prostate hypertrophy?
May be prescribed to treat chronic prostatitis = inflammation of the prostate, which may accompany BPH
List 4 symptoms of BPH which may lead to prostate surgery being recommended
Recurrent blood in the urine
Inability to fully empty bladder (urinary retention)