Urinary Bladder, Micturition + Infections

Question 1

Where is the bladder situated?

Answer 1

Pelvic cavity
BUT expands superiorly into abdominal cavity

Question 2

What are the 4 parts of the bladder?

Answer 2

Apex
Base
Superior surface
Inferolateral surfaces

Question 3

What is the trigone?

Answer 3

Smooth triangular area between the openings of the ureters + urethra on the inside of the bladder

Question 4

What does the sympathetic nerve do?
PART 1

Answer 4

Transmits impulses from the pain receptors to the upper lumbar segment
= perception of pain from urethra + bladder

Question 5

What does the pelvic nerve do?
PART 2

Answer 5

Transmit impulses from tension + pain receptors in wall of bladder
To sacral region of spinal cord
= reflex micturition + sensation of bladder fullness

Question 6

What does the pudendal nerve do?
PART 3

Answer 6

Transmit impulses for the sensation of …
Distension of urethra
Passage of urine through urethra
Maintains tonic contractions of skeletal muscle fibres of external sphincter

Question 7

Describe the sympathetic supply to the bladder

Answer 7

Preganglionic fibres from upper 4 L
Fibres on both sides unite to form presacral nerve
Which divide into postganglionic nerves

Question 8

What are the functions of the sympathetic nerves?

Answer 8

Inhibitory to bladder wall (detrusor muscle)
Motor to internal urethra sphincter
Motor to seminal vesicle, ejaculatory duct + prostatic musculature

Question 9

What is the muscle in the bladder wall called?

Answer 9

Detrusor muscle

Question 10

What is found the detrusor wall?

Answer 10

Beta receptors (2+3)

Question 11

What is found in the internal urethral sphincter?

Answer 11

Alpha-1 receptors

Question 12

Describe the parasympathetic supply to the bladder

Answer 12

Preganglionic fibres arise from 2nd, 3rd + 4th sacral segments
Form pelvic nerve
Which relays in terminal ganglia in wall of urinary bladder

Question 13

What are the functions of the parasympathetic nerves?

Answer 13

Motor to bladder wall (detrusor muscle- M3)
Inhibitory to internal urethral sphincter = urine will be released

Question 14

Describe the somatic supply to the bladder

Answer 14

Arises from 2nd, 3rd + 4th sacral segments
Supplies the external urethra sphincter

Question 15

What is the function of somatic supply?

Answer 15

Motor to external urethral sphincter

Question 16

What is the external urethral sphincter?

Answer 16

Nicotinic receptors

Question 17

How does the urethra empty on females?

Answer 17

By gravity

Question 18

How does the urethra empty in males?

Answer 18

By several contractions of bulbocavernous muscle

Question 19

What happens in the brain in micturition?

Answer 19

Central coordination occurs in pontine micturition centre
Parietal lobes + thalamus receive + coordinate detrusor afferent stimuli
Whilst frontal lobes + basal ganglia provide modulation with inhibitory signals

Question 20

What happens when bladder is empty?

Answer 20

Hypogastric nerve activated (sympathetic)
= inhibitor detrusor muscle from contracting
Pelvic nerve quiet (parasympathetic)
Pudendal nerve activated (somatic)
= external urethral sphincter closed

Question 21

What happens when the bladder is full?

Answer 21

Potine micturition centre activated
Hypogastric nerve deactivated
= contraction of detrusor muscle
Pelvic nerve activates bladder
= contracts
Pudendal nerve deactivated
= external urethral sphincter relaxes
= wee

Question 22

What happens if the condition is favourable?

Answer 22

Cortical centre facilitates micturition by discharging signals =
Stimulation of sacral micturition centre
Inhibition of pudendal nerve
= relaxation of external urethral sphincter
Contraction of anterior abdominal muscle + diaphragm
= increase intra-abdominal pressure
= intra-vesicle pressure increased
Voiding under parasympathetic regulation

Question 23

What happens if the condition is unfavourable?

Answer 23

Inhibit micturition reflex by =
Inhibition of sacral micturition centre
Stimulation of pudendal nerves
= contraction of external urethral sphincter
Holding of urine under sympathetic regulation

Question 24

What is a cystometrogram?

Answer 24

Plot of intravesical pressure against volume

Question 25

What changes with age?

Answer 25

Detrusor overactivity increases Postpone voiding decreases Detrusor contractility decreases

Question 26

What is an atonic/hypotonic bladder due to?

Answer 26

Destruction of sensory nerve fibres from bladder

Question 27

What happens to a atonic/hypotonic bladder?

Answer 27

Bladder muscle loses tone + becomes flaccid Bladder fills to capacity + overflows = overflow dribbling

Question 28

What is the treatment for atonic/hypotonic bladder?

Answer 28

Bladder catheterisation + correction of underlying causes

Question 29

What is an automatic bladder due to?

Answer 29

During spinal shock after complete transection of spinal cord

Question 30

How is automatic bladder treated?

Answer 30

After spinal shock has passed (2-6 weeks), voiding reflex returns

Question 31

What is uninhibited neurogenic bladder due to?

Answer 31

Lesions in some parts of brain stem = continuous excitation of spinal micturition

Question 32

What happens in uninhibited neurogenic bladder?

Answer 32

Uncontrollable micturition

Question 33

What is nocturnal micturition (bed wetting) due to?

Answer 33

Incomplete myelination of motor nerve fibres = loss of voluntary control of micturition

Question 34

What is overactive bladder due to?

Answer 34

Detrusor instability Stroke, spinal injury + MS Medications

Question 35

What is urethral sphincter incompetence?

Answer 35

Dribbling with incomplete bladder emptying

Question 36

What is urethral sphincter incompetence due to?

Answer 36

Impaired detrusor contractility + bladder outlet obstruction Loss of collagenous support in pelvic floor = women

Question 37

What is painful bladder/interstitial cystitis due to?

Answer 37

Urothelial abnormalities Central sensitisation + increased activation of bladder sensory neurons Increase in visceral sensitivity