Bladder Function

Question 1

what is the function of the detrusor muscle

Answer 1

smooth muscle
allows large volume changes
activity of detrusor muscle affected by reflexes
passive stretch of the wall triggers contractions
contractions of detrusor muscle produces additional force/ pressure

Question 2

what does the multi-barrel catheter do

Answer 2

allows fluid to fill the bladder at a controlled rate
allows pressure to be measure at several site simultaneously
- e.g. bladder, sphincter
some devices allow recording of sphincter activity

Question 3

describe the steps to hold a multi-barrelled catheter in place

Answer 3

1- place one opening in the bladder to allow direct filling and measure bladder pressure
2- Inflate balloon to close of urethra
3- position second opening in the urethra to measure the sphincter pressure
4- then fill the bladder and record the pressure to establish bladder compliance
5- as bladder fills watch for signs of bladder wall contraction and sphincter contraction

Question 4

what are the conditions for bladder filling

Answer 4

sphincter pressures/ urethra pressures > vesicle pressures
no flow out

Question 5

what are the conditions for bladder voiding

Answer 5

vesicle pressures > sphincter/ urethra pressures
fluid pushes past sphincter to escape

Question 6

describe male bladder muscle

Answer 6

strong external sphincter
skeletal muscle

Question 7

describe female bladder muscle

Answer 7

less skeletal muscle
weaker external sphincter
damage during childbirth

Question 8

what are the two stages of bladder voiding

Answer 8

storage phase
voiding phase

Question 9

describe the progress of the storage phase

Answer 9

1- early filling phase, low pressure in bladder, bladder wall and external sphincter relaxed
2- no flow in urethra - urethral pressure > bladder pressure
3- sensations develop (sensation point (s))
4- sphincter contracts to maintain continence

Question 10

describe the progress of the voiding phase (part 1)

Answer 10

1- 1UM (1st urge to micturate)
2- 1VV (voluntay voiding)
3- Rise in bladder pressure caused by contraction of the bladder wall
4- internal sphincter + external sphincter begin to relax

Question 11

voiding phase (part 2)

Answer 11

1- pressure continues to rise as bladder contracted but no voiding occurring
2- pressure decreases in bladder as the muscle relaxes
3- 2VV
4- pressure increases again to allow full voiding

Question 12

what is the reason for the possible pauses in micturition

Answer 12

external sphincter is skeletal muscle which changes force faster
urethra is smooth muscle with changes forces slower
- possible pauses in beginning of voiding (waiting for pressures to increase in smooth muscle)
- possible pauses in end of voiding (skeletal muscle in sphincter contracts faster)

Question 13

why does micturition require differential control

Answer 13

smooth muscle in bladder wall contracts
smooth muscle in urethra

Question 14

what innervates the bladder wall and internal sphincter

Answer 14

sympathetic - from L1 and L2

Question 15

what innervates the bladder wall

Answer 15

parasympathetic - S2, S3 and S4

Question 16

what innervates the external sphincter

Answer 16

somatic (voluntary) - S2, S3 and S4

Question 17

what do the afferent nerves do in terms of bladder control

Answer 17

sensory fibres sense the stretch of the bladder wall
these run in the hypogastric nerve and enter cord in the upper lumbar roots
other sensors near the urethra sense flow of urine
skeletal muscle sensors in the external sphincter

Question 18

what do the efferent nerves do in terms of bladder control

Answer 18

parasympathetic to detrusor muscle
sympathetic to internal sphincter

Question 19

describe the control of the storage phase

Answer 19

sympathetic - effects dominate during bladder filling
fibres in the hypogastric nerve suppress contraction of the detrusor
somatic fibres in the pudendal nerve control the external sphincter

Question 20

describe the control of the voiding phase

Answer 20

parasympathetic - action dominate during emptying
fibres in the pelvis splanchnic nerve cause the detrusor to contract

Question 21

describe the reflex control of the bladder

Answer 21

via centres in the sacral cord and in the pons
pontine centre coordinates with higher centres

Question 22

describe the progression of sensations

Answer 22

no sensation -> sense of filling -> fullness -> desire -> discomfort -> pain

Question 23

what factor does sensations depend on

Answer 23

sensations depend on rate of filling
faster = lower volume to reach sensations
also temperature -> cooler increases the sensation

Question 24

what are sensations supported by

Answer 24

large myelinated fibres and small unmyelinated fibres
- small fibres probably linked to the unpleasant sensations

Question 25

what is the differences in volume and pressure in the storage phase and voiding phase

Answer 25

storage phase -> lower pressure, volumes -> relates to urine production rates
voiding phase - higher pressures, look at flow rates, relate to emptying times

Question 26

what is a neurogenic bladder

Answer 26

reflexes very active
bladder wall very stiff
contraction starts at lower volume
more frequent desires for micturition

Question 27

what is an atonic bladder

Answer 27

pressure rises slowly as bladder fills
too compliant
difficult to void bladder

Question 28

what is the treatment for atonic bladder

Answer 28

catheter (intermittent catheterisation)
RISK OF INFECTION

Question 29

describe benign prostatic hyperplasia

Answer 29

enlargement of the prostate that restricts flow through the urethra
more frequent micturition
can lead to infection because of stagnant urine
- secondary infection