Micturition

Question 1

1. Which nerve carries parasympathetic innervation of the bladder?
2. What is its function?

Answer 1

1. Pelvic Nerve

2. Contraction of the detrusor muscle > micturition

Question 2

1. Which nerve carries somatic innervation of the bladder?

2. What is its function?

Answer 2

1. Pudendal Nerve

2. Voluntary contraction of the external sphincter > voluntary urinary retention

Question 3

1. Which nerve carries sympathetic innervation of the bladder?
2. What is its function?

Answer 3

1. hypogastric nerve
2. relaxation of the detrusor muscle
   contraction of the internal sphincter
   BOTH FUNCTIONS PROMOTE URINARY RETENTION

Question 4

1. Which nerve carries sensory innervation of the bladder?

2. What does this nerve respond to?

Answer 4

1. Pelvic nerve

2. bladder stretch

Question 5

Describe the micturition reflex when the bladder is empty

Answer 5

slow firing from pelvic afferent fibres to spinal cord
stimulation of sympathetic hypogastric nerve
inhibition of parasympathetic pelvic nerve
higher centres stimulate pudendal nerve - voluntary contraction of external sphincter

Question 6

Describe the micturition reflex when the bladder is full

Answer 6

rapid firing from pelvic afferents to the spinal cord and higher micturition centres
inhibition of sympathetic hypogastric nerve
stimulation of parasympathetic pelvic afferents > contraction of detrusor
voluntary inhibition of pudendal nerve > relaxation of external sphincter