Session 8

Question 1

Key muscular components of the bladder

Answer 1

Question 2

Result of urodynamics

Answer 2

Able to infuse a large volume of urine into the bladder with minimal change in pressure

Up to approx 150-200ml

Question 3

As volume of urine increases the increase of pressure within the bladder is

Answer 3

Not linear

Question 4

What are the 2 phases of urodynamics

Answer 4

Storage phase, voiding phase

Question 5

What is storage phase

Answer 5

Ability of the bladder to increase in volume with no appreciable change in pressure

Question 6

What is voiding phase

Answer 6

Contraction of detusor to enable voiding (spikes in pressure)

Question 7

Graph of Pressure and volume in bladder

Answer 7

Question 8

Explain storage phase reflex

Answer 8

• Starts with sensory neuron
• Stretch receptor detects stretch of bladder wall
• Innervated by sensory neuron (enter sacral cord between S2-4, ascend to T10-L2)

Sensory neuron synapse upon sympathetic neurones

Sympathetic neurons project to detrusor (inhibitory effect) and IUS (stimulatory effect), as bladder volume increases the detrusor stays relaxed (no appreciable increase in pressure)

Question 9

Explain storage phase cortical control

Answer 9

-Stretch receptors also report to cerebral cortex
-EUS made of skeletal muscle, controlled by somatic neurones
-Found between S2-S4, project to EUS, excitatory

L centre within brainstem send axons to somatic motor neurones, keeps EUS closed and maintain continence

Question 10

Rhyme to remember nutrition area in sacral cord

Answer 10

S2-3-4 keeps the shit off the floor

Question 11

Why do we want the bladder to be relaxed

Answer 11

So it can fill

Question 12

Explain voiding reflex

Answer 12

Need a sensory receptor
Stretch receptor, innervated by sensory neurone, enters spinal cord S2-S4

Synapse upon parasympathetic neurones, project to detrusor are excitatory causing contraction

Creates a reflex arc- result in micturition

Question 13

Explain voiding cortical control

Answer 13

High levels of bladder stretch = sensory neurones activate the M centre

M (micturition) centre is medial to L centre
- Send excitatory inputs down Parasympathetics
- Positive feedback loop

M centre is not autonomous (PCL send excitatory and inhibitory influences)

Question 14

Overall micturition diagram

Answer 14

Question 15

Communications between M and L centres

Answer 15

M centre send projections to L centre (inhibitory)

When you wish to void you strongly stimulate the M centre, activates the parasympathetics causing detrusor contraction

Inhibits the L centre- relaxation of L centre by switching off pudendal nerve