Session 8 Flashcards
Define Micturation
To want to pass urine (Controlled entirely by the spinal cord)
Define Detruser
To push down
What controls the Urine storage phase?
Neurones of the sympathetic system (Root values L1 & L2)
What controls the bladder voiding phase?
Neurones of the parasympathetic system (Root values S2, S3 & S4)
What are the 2 urethral sphincters?
Internal and External
What type of sphincter is the Internal urethral sphincter?
A physiological one - It is a passive valve made by a specific tissue arrangement. As the bladder fills, it forces the valve to close
What supplies the body of the urinary bladder?
The ANS (Parasympathetic & Sympathetic) Not under voluntary control
What supplies the External urethral sphincter?
The Somatic nervous system
Under voluntary control (From cerebral cortex via the spinal cord)
What is important to remember about the neural control of the urinary bladder?
It is a balance between somatic and autonomic divisions of the nervous system
What is autonomic dysreflexia?
The body loses control of the bladder
It fills and can cause issues
What is the histiological properties of the Detrusor muscle of the urinary bladder?
Smooth muscle with no peristaltic activity
Lined with transitional epithelium - Non secretory
It contracts and relaxes wholly
What is the significance of the Detrusor muscle being able to contract and relax wholly?
When it starts emptying, it empty completely
What are the 2 general functions of the urinary bladder?
Phase I - Temporary storage of urine
Phase II - Expulsion of urine
What can the epithelium of the urinary bladder do during Phase I?
Can temporarily absorb some water, but not for long because they do not want to absorb it into the body
What is Phase I also known as?
The Continence phase
What is Phase II also known as?
The Micturition phase
What controls the Continence phase?
A dedicated set of neurones called continence neurones
What may happen if you damage the continence neurones?
The bladder can no longer store urine which leads to reduced bladder capacity and incontinence (Many types of incontinence)
What will happen if you damage the neurones controlling Micturition? (Different set to continence neurones)
Cannot voluntarily pass urine so leads to urinary retention. Urine is only passed when the urinary bladder is overflowing
What is it called when urine is only passed due to the urinary bladder overflowing?
Overflow incontinence. Need to catheterise
What is it called when a patient cannot void their urinary bladder?
Urinary retention. Need to catheterise
What does the external uretheral sphincter do when the bladder relaxes?
It closes/contracts
What does the external urethral sphincter do when the bladder contracts?
It relaxes
What is the name for disturbances to the synchrony of detruser muscle and external urethral sphincter?
Detrusor - Sphincter dyssenergia (Leads to a build up of urinary pressure as the bladder cannot empty properly
What are the neural apparatus involved in the Continence phase called?
Continence circuits (In the spinal cord) and Continence centres (In the brain)
Where are Pontine centres?
In the brain stem
What are Pontine centres?
Neuronal centres that rely information from the Cerebral cortex to sympathetic nuclei in the spinal cord
What are Pontine Continence circuits?
Bilateral outputs from the Pons (In the brain stem)
What do Pontine Continence circuits control?
Silence electrical activity of the Detrusor muscle
Relaxation of Detrusor muscle (Beta 3 in body and fundus of urinary bladder)
Increase urethral sphincter pressure (alpha adrenoceptors in neck of urinary bladder)
Encourage storage of urine
What 2 nervous systems are in balance for spinal urinary continence?
Sympathetic nervous system
Somatic nervous system
What does the Sympathetic nervous system control in the urinary bladder?
Relaxed Detrusor muscle via Beta 3 receptors
Internal urethral sphincter constriction leading to neck closure via alpha adrenoceptors
What does the somatic nervous system control in the urinary bladder?
Activates closure of the external urethral sphincter via Ach action at the neuromuscular junction
What root values of the sympathetic nervous system supply the urinary bladder?
T10/T12-L2 (Thoracico-lumbar cord)
What root values of the somatic nervous system supply the urinary bladder?
S2-S4 (Onuf’s nucleus)
What property of the urinary bladder wall increases its storage?
There are rugae in the walls so they can distend as the urinary bladder fills (Causes the internal urethral sphincter to close and for intravesical pressure to remain fairly constant)
What are the effects of a lesion on a continence circuit?
Cannot store urine Decreased bladder capacity Excessive detrusor muscle activity Premature voiding Relaxation of urethra Incontinence
How does the urinary bladder sense it needs to empty?
Afferent nerves (Parasymapthetic origin) sit in the wall of the urinary bladder with stretch receptors. Mild pain sensation that is localised (Do NOT have referred pain)
What controls the Voiding phase of the urinary bladder?
Micturition centres of the brain that activate micturition centres of the spinal cord (Voiding circuits arising from the pons) Parasympathetic neurones of the sacral division
What do Voiding circuits cause?
Contraction of the detrusor muscle
Increase in pressure
Relaxation of the internal urethral sphincter
Voluntary relaxation of the external urethral sphincter
Expulsion of urine
What causes the External urethral sphincter to relax?
Cerebral cortex (Somatic) Spinal root values S2-S4 cause relaxation
What increases Detrusor activity?
The parasympathetic division of the ANS, root values S2-S4
What is the nerve supply of the bladder?
Purely autonomic.
No motor or sensory representation of the urinary bladder in the motor cortex (Meaning sensation and voiding do not need to be under conscious control)
What is the External urethral sphincter?
Muscles of the pelvic floor overlay to form a sphincter.
What nerve supplies the External urethral sphincter?
Perineal branch of the Pudendal nerve. Root values S2-S4.
What is Stress urinary incontinence?
Fine until sneeze or cough when get involuntary leakage
What is Urge urinary incontinence?
Urgency to go to the toilet
