Flashcards in Ureter and Bladder Deck (40):
What are the two parts of the urinary bladder?
What is the internal sphincter of the bladder?
The detrusor muscle
The natural tone of which sphincter keep urethra empty of urine?
The detrusor muscle
Which sphincter is voluntary, the internal or the external?
What is the motor sensation to the bladder?
Pelvic (S2, S3, S4)
Hypogastric (L1, L2, L3)
What are the sensory nerves that supply the bladder/trigone/internal sphincter?
Hypogastric n (L1, L2, L3)
Pelvic nerves (S2, S3, S4)
What does the pudendal nerve supply in terms of the bladder?
Both motor and sensory somatic nerve fibers to external sphincter
Is the fluid that moves from the kidneys to the bladder via the ureters changed?
What pushes urine into the ureters?
The walls of the renal calyces, pelvis and ureters have contractile elements that are used to push the fluid into the bladder
What controls the smooth muscle contraction of the renal calyces?
Inherent pacemaker activity
Are there any real urethral sphincters? What keeps them compressed?
No--the detrusor muscle keeps them compressed
What is vesicoureteral reflux?
In some people the ureters’ path through the bladder wall is less oblique and shorter. During urination when the bladder contracts their ureters are not always totally closed. This permits the backward flow of urine into the ureters.
What causes the intense pain felt in renal stones?
Ureteral peristaltic contractions
What is the ureterorenal reflex?
Sensory nerves to the ureters can sense if there is increased stretch from a blockage, and will stop further urine formation in the kidneys by constricting afferent arterioles
As urine enters the bladder, the intravesical pressure rises how?
Quick rise, then slower with additional urine
What causes the acute pressure spikes seen in the micturition reflex?
Bladder sends signals to the sacral spinal cord, which sends back parasympathetic impulses to the detrusor to contract. This is a positive feedback loop until the detrusor fatigues. This will happen more often with more urine, thus causing the urge to micturate
Is the micturition reflex autonomic or somatic? Can it be inhibited or facilitated by the brain?
Fully autonomic, but can be regulated by the brain
What centers of the brain normally inhibit the micturition reflex? What do these do?
Cortical and suprapontine
Send efferent signals to the parasymp nerves in the sacrum to inhibit the nerves that stimulate detrusor muscle
What is the sympathetic storage reflex?
As the bladder distends, it sends afferent signals to the spinal cord. There, symp firing via L1-L3 is initiated, decreasing excitatory parasymp inputs to the bladder
What is the somatic storage reflex (pelvic to pudendal reflex)?
Afferent activity d/t increased intra abdominal pressure travels to the pelvic nerves. where efferent nerves are activated. These are are usually tonically active, but are suppressed when this reflex arc occurs, to allow for micturition
What is the center in the brain that controls urination?
Pontine micturition center
When the bladder fills to approx what volume does a person feel the urge to urinate?
Voluntary urination is initiated how?
Partially by voluntary relaxation of the external urinary sphincter and perineal muscles.
What is meant by the term neurogenic bladder?
a general term for when the urinary bladder malfunctions because of neurological dysfunction
What causes an atonic bladder?
Sensory nerve fibers from the bladder to the spinal cord are destroyed.
Patient cannot have micturition reflex since the sensory signals from the bladder are missing
What are the symptoms of an atonic bladder?
the bladder becomes filled to capacity and then overflows a few drops at a time through the urethra.
What can cause atonic bladder?
Crush injury to sacrum
Tertiary syphilis d/t sacral dorsal root disruption
What is an automatic bladder? Are the micturition reflexes intact?
A type of neurogenic bladder caused by spinal cord damage above the sacral region.
Typical micturition reflexes can still occur since all three neural components are intact: sensory nerves from bladder, motor nerves to bladder and area of spinal cord where reflex connections made.
What are the symptoms of an automatic bladder?
No voluntary control over micturition, but fully voids.
What is a possible complication with automatic bladder?
Patient may develop spastic neurogenic bladder with decreased bladder capacity and reflex hyperactivity
What causes an automatic bladder?
the eventual bladder dysfunction caused by a spinal cord lesion above the sacral cord is automatic bladder
What is an uninhibited neurogenic bladder?
A type of neurogenic bladder is caused by partial damage in the spinal cord or the brain stem that interrupts most of the descending inhibitory signals but leaves descending facilitory signals intact
What are the symptoms of an uninhibited neurogenic bladder? Why?
Frequent, and uncontrolled micturition
Continual excitation of sacral centers makes them so excitable that even a small amount of urine in the bladder elicits an uncontrollable micturition reflex.
What is the parasympathetic supply to the bladder?
What is the sympathetic supply to the bladder?
What is the nerve supply to the external sphincter?
Ureteral peristaltic contractions are due to what innervation?
Atonic bladder is the result of what? What type of urination?
No sensation to bladder
Leads to dribbling ("overflow incontinence")
Automatic bladder is the result of what? What type of urination?
Total loss of connection with brain (crush injury)
Leads to full expulsion of urine, just uncontrolled by brain