Function of the Bladder

Question 1

what is the minimum rate of urine production?

Answer 1

1ml/min

Question 2

what is the maximum rate of urine production?

Answer 2

20ml/min

Question 3

what do stretch receptors in the bladder wall do?

Answer 3

as bladder fills they generate signals to tell brain how full it is

Question 4

what do sphincters do?

Answer 4

control the flow of urine

Question 5

what is the conscious control of the bladder?

Answer 5

can be controlled consciously and unconsciously

Question 6

what are cysometrogram?

Answer 6

measure bladder behaviour as it is stretched and compliance

Question 7

what is the detrusor?

Answer 7

smooth muscle of bladder wall

Question 7

what is the distinctive feature of the bladder wall?

Answer 7

allows large volume changes

Question 8

how is the detrusor controlled?

Answer 8

autonomic reflexes
passive stretching of the wall triggers contractions

Question 9

how is a cystometrogram done?

Answer 9

-multi barrel thin tube catheter
-allows fluid to fill bladder at a controlled rate
-allows pressure to be measured at several sites simultaneously: bladder, sphincter

Question 10

what happens to pressure within the bladder when it fills?

Answer 10

urethra pressures > vesicle pressures = no flow out

Question 11

when will bladder empty?

Answer 11

vesicle pressure > sphincter pressure or urethra pressure = fluid pushes past the sphincter

Question 12

what are the stages of the storage phase?

Answer 12

1. early filling phase
2. no flow in urethra
3. sensations develop

Question 13

what happens during the early filling phase?

Answer 13

low pressure in bladder
bladder wall and external sphincter relaxed. no bladder sensation

Question 14

what happens in the second stage?

Answer 14

no flow in urethra
urethral pressure > bladder pressure

Question 15

what happens in the third phase?

Answer 15

sensations develop, sphincter contracts to maintain continence

Question 16

what are the stages of the voiding phase?

Answer 16

1. urge then voluntary voiding
2. bladder contracts, urethra and sphincter relax. bladder pressure > urethral pressure
3. voluntary stop flow then a 2nd voiding phase

Question 17

what is the complex coordination?

Answer 17

external sphincter is skeletal muscle which changes force faster. urethra is smooth muscle which changes force slower. smooth muscle in bladder wall contracts. smooth muscle of urethra relaxes.

Question 18

what is the innervation of the bladder and sphincters like?

Answer 18

sympathetic : from L1, L2 (bladder wall and internal sphincter)
parasympathetic : S2, S3 and S4 (bladder wall)

Question 19

what is the afferent pathway ?

Answer 19

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

Question 20

what is the efferent point?

Answer 20

parasympathetic to detrusor
sympathetic to internal sphincter
somatic to external sphincter

Question 21

storage phase?

Answer 21

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 22

voiding phase?

Answer 22

parasympathetic actions dominante during emptying
fibres in the pelvic sphlanic nerve cause the detrusor to contract.

Question 23

reflex control?

Answer 23

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

Question 24

which nerve fibres feel the sensations in the bladder?

Answer 24

-larger myelinated fibres
-small unmyelinated fibres
-small fibres are probably linked to unpleasant sensations

Question 25

what is the basal cystometrogram?

Answer 25

everything relaxed, no contractions in bladder wall

Question 26

what is. neurogenic bladder?

Answer 26

contractions start at a lower volume

Question 27

what is an atonic bladder?

Answer 27

pressure rises slowly as bladder fills

Question 28

what is the plumbing problem?

Answer 28

when urethra passes through prostate gland
-likely due to hypertrophy of the prostate with age
-can compress the urethra and slow the flow of urine
-can open up potential for toilet
-can prevent full emptying of bladder