Urinary contience

Question 1

Name four types of incontinence

Answer 1

1. Stress incontinence - leakage when the muscles are stressed eg coughing or straining - due to a weak spincter
2. Urge incontinence - leakage with urgency - over activity, frequent need to urinate
3. Retention with over flow - continuous dribbling
4. Anatomical - continuous dribbling with normal voids, structure problems
   - congenital eg ectopic ureter
   - acquired eg, fishula following hysterectomy

Question 2

Who is most likely to be incontinent?

Answer 2

• Women (particularly after childbirth)

- Elderly

Question 3

What are the sphincters of the bladdder?

Answer 3

• Bladder neck
• Distal urethral sphincter
  a) Smooth muscle component
  b) intrinsic striated sphincter
  c) extrinsic striated sphincter

Question 4

How is the cortex involved in voiding?

Answer 4

Cortex - sensation, voluntary initiation

Question 5

How is the midbrain involved in voiding?

Answer 5

1. Pontine micturition center (PMC) - When activated, the PMC relaxes the urethral sphincter allowing for micturition to occur.
2. Periaqueductal gray (PAG) acts as a relay station for ascending bladder information from the spinal cord and incoming signals from higher brain areas
3. Completion of voiding

Question 6

How are spinal reflexes involved in voiding?

Answer 6

-Reflex bladder contraction - sacral micturition centre (micromotion coordination)

• guarding reflex - onuf’s nucelus (Onuf’s nucleus connects directly to the rhabdosphincter muscle which is part of the external urethral sphincter to control micturition)
  1) normal urine storage this pathway is tonically active
  2) during sudden unexpected increase in bladder pressure, it becomes dynamically active to contract the rhabdosphincter 9via Onuf’s nucleus)

-receptive relaxation - symp?

Question 7

How is micturition different in adults compared with children?

Answer 7

In a non-toliet trained toddler reflex bladder is dominant - no control, reflex bladder and coordinated voiding
Adult’s have voluntary control of voiding and contience
-In old age reflex bladder and coordinated voiding due to weakened muscles, and neuro disease

Question 8

Where is the parasympathetic control of micturition?

Answer 8

SACRAL micturition centre

• parasympathetic S2,3,4
• Intermedial lateral grey
• coordination of micromotions

(C fibres local afferents) - reflex bladder

Question 9

Where is the sympathetic control of micturition?

Answer 9

Bladder - receptive relaxation
Bladder neck
Sphincter - smooth muscle, non-relaxing

Question 10

1. Pontine micturition center (PMC)

Answer 10

2 areas
medial - micturition
lateral - storage
-motor centre for autonomic cnotrol of lower urinary tract
-descending fibres presumed to be in antero-lateral funiculus

Question 11

2. Periaqueductal gray (PAG)

Answer 11

Visceral and somatic control centre for lower urinary tract

• receives Alpha Gamma fibre input
• communicates with conscious centres

Question 12

Give a brief overview of the nervous control of micturition

Answer 12

Sensory input from bladder to spinal cord through parasympathetic nerves to S2,3,4, tells the cord and brain that the bladder if filling. Spinal reflex passes some of these signals to the motor parasympathetic nerves which supply the detrusor muscle and inhibit the internal urethral sphincter. If it is not socially convenient to urinate brain inhibits these impulses. When in toilet (hopefully) brain stops inhibition and parasympathetic motor nerves via s2,3,4 cause detrusor muscle to contract and internal sphincter to relax.