Urinary Bladder, Microturition and Infections Flashcards
what is the function of the bladder?
a temporary storage of urine that can empty at an appropriate time
where is the bladder situated when empty?
in the pelvic cavity
where is the bladder situated when full?
partly in the pelvic cavity but expands superiorly into the abdominal cavity
at what age does the bladder descend into the pelvis area from the abdominal area?
by the 5th or 6th age
what are the 4 parts of the urinary bladder?
- apex
- base
- superior surface
- inferolateral surface
what is the mucosal lining of the base of the bladder like?
smooth firmly attached to the wall
what is the mucosal lining of the base of the bladder attached to?
the underlying smooth muscle coat of the wall
what is the mucosal lining of the bladder like elsewhere besides the base?
folded and loosely attached to the wall
what is the trigone?
he smooth triangular area between the openings of the ureters and urethra on the inside of the bladder
what is the main difference between a male and female’s bladder and urethra?
males have an internal and external urethral sphincter but females only have an external one.
what does the sympathetic nerve do to the bladder?
transmit impulses from the pain receptors to the upper lumbar segment resulting in the perception of pain sensation from the urethra & bladder.
what does the pelvic (parasympathetic) nerve do to the bladder?
transmit impulses from the tension and pain receptors present in the wall of the bladder to the sacral region of spinal cord resulting in both reflex micturition & sensation of bladder fullness
what does the pudendal (somatic) nerve do to the bladder?
transmit impulses for the sensation of: Distention of the urethra. Passage of urine through the urethra. Maintains the tonic contractions of the skeletal muscle fibers of the external sphincter.
how does the pelvic nerve work?
releases ACh at the M3 receptor on the bladder to cause muscle contraction to force the urine out
how does the sympathetic nerve work?
releases noradrenaline at the bladder beta receptor and urethra alpha receptor to:
1. inhibit contraction of the bladder
2. stimulate contraction of the urethra.
Both to prevent urine release
How does the pudendal (somatic) nerve work?
releases ACh at the nicotinic receptors of the external urethral sphincter to cause contraction hence preventing urine release
what fibres supply the sympathetic system in the bladder?
The preganglionic fibres which branch from the upper 4 lumbar vertebrate.
The postganglionic fibres arise from the hypogastric ganglia
what are the functions of the sympathetic nerves?
Inhibitory to the bladder wall (detrusor muscle).
Motor to the internal urethral sphincter.
Motor to the seminal vesicle, ejaculatory duct & prostatic musculature. It prevents the reflux of semen into the bladder.
what is the wall of the bladder called?
the detrusor wall
what fibres supply the parasympathetic system in the bladder?
the preganglionic fibres from the 2nd, 3rd and 4th sacral segments the vertebrate
what are the functions of the parasympathetic nerves?
Motor to the bladder wall (detrusor muscle).
Inhibitory to the internal urethral sphincter.
what fibres supply the somatic system in the bladder?
-they arise from the 2nd, 3rd and 4th sacral segments and supplies the external urethral sphincter
what is the function of the somatic supply?
Motor to the external uretheral sphincter.
when does the micturition reflex start to appear??
from stage 1 when the bladder reaches 150-300ml. So the early stage of feeling the urge to urinate
at what point can micturition no longer be suppressed?
at about 700ml (break point)
what is the storage phase of micturition?
the filling phase
what is the voiding phase of micturition?
the emptying phase
what helps to empty the female urethra?
gravity
how is urine in the urethra of the male expelled?
by several contractions of the bulbocavernosus muscle.
what part of the brain receives and coordinates the detrusor afferent stimuli?
The parietal lobes and thalamus
what part of the brain provides modulation with inhibitory signals?
the frontal lobes and basal ganglia
where does central coordination occur?
in the pontine micturition centre
The cortical centres facilitate micturition by discharging signals which leads to what?
Stimulation of sacral micturition center.
Inhibition of pudendal nerves which causes relaxation of external urethral sphincter.
Contraction of anterior abdominal muscle & diaphragm to increase intra-abdominal pressure. This intensifies the micturition reflex.
Voiding under parasympathetic regulation (pelvic nerve)
The higher centres inhibit micturition by what?
Inhibition of sacral micturition center.
Stimulation of pudendal nerves ⇒ contraction of external urethral sphincter.
Holding of urine under sympathetic regulation (hypogastric nerve)
what is a cystometrogram?
a graph of the pressure applied on the bladder against the volume of urine in the bladder
What are the 3 types of incontinence?
- overflow
- stress
- urge
what is overflow?
blockage of the urethra so the bladder can’t empty properly
what is stress?
when the pelvic floor is relaxed causing increased abdominal pressure
what is urge?
when the bladder is oversensitive due to an infection that causes neurological disorders.
what is atonic (hypotonic) bladder?
- when the sensory nerve fibers from the bladder are destroyed e.g. by a disease, injury
- causes the person to loose bladder control as the bladder muscle looses the tone and becomes flaccid so urine overflows and drips through the urethra.
how to treat atonic bladder?
- Bladder catheterization and correction of the underlying causes
- Neurogenic problems treated with anticholinesterases to increase detrusor contraction.
what type of drugs make atonic bladder worse?
antimuscarinics
what is Spastic neurogenic (automatic) bladder?
- During spinal shock after complete transection of spinal cord above sacral centres of micturition, the urinary bladder looses its tone and becomes flaccid and unresponsive causing overflow.
- spinal shock due to sudden separation of the spinal centres from the higher centres that control them
- when bladder is filled with some amount of urine, there is automatic evacuation of the bladder
what is uninhibited neurogenic bladder?
- a lesion in some parts of the brain stem interprets inhibitory signals so we get continuous excitation of spinal micturition centres by the higher centres.
- micturition is now uncontrolled increasing need to urinate
what is Nocturnal micturition?
AKA bed wetting:
- common in infants and kind <3yrs old
- occurs due to incomplete myelination of motor nerve fibers of the bladder resulting loss of voluntary control of micturition
what is Overactive bladder syndrome?
when the detrusor produces uncontrolled bladder contractions during normal filling.
- can be associated with a stroke, spinal injury, MS
- can also be secondary to the meds already taking
- causes urinary urgency and frequency, nocturia
what is urethral sphincter incompetence?
- Dribbling and/or continuous leakage associated with incomplete bladder emptying, due to impaired detrusor contractility and/or bladder outlet obstruction.
- Urethral sphincter incompetence produces stress incontinence in women (urine leakage with effort, exertion, coughing etc.) or sphincter weakness incontinence in men.
what is Painful bladder syndrome/interstitial cystitis (PBS/IC)?
- urothelial abnormalities alter bladder epithelial expression of HLA Class I and II antigens
- so the bladder sensory neurones are activated during normal bladder filling
