28. Urinary Bladder and Micturition

Question 1

What is the innervation of the ureters?

Answer 1

Autonomic NS

Question 2

What type of epithelium is found in the ureters?

Answer 2

Transitional, allows for stretch

Question 3

What is the function of the oblique path of the ureters against the bladder wall?

Answer 3

Creates a valve
Tone of detrusor muscle keeps the ureter compressed
Reduces urinary reflux and damage

Question 4

What causes urine to flow from renal calices?

Answer 4

Calices stretched from vol of urine
Stimulates inherent pacemaker activity
Initiates peristalsis

Question 5

What is the ureterorenal reflex?

Answer 5

Blockage of the ureter causes build up of urine above the block and pain
Reflex activation of sympathetics to the afferent arteriole
Decreases urine output

Question 6

What is hydronephrosis?

Answer 6

Swelling of kidney due to build-up of urine

Question 7

Why does an increase in urine volume not cause a change in pressure in the bladder up to a certain point?

Answer 7

Transitional epithelium allows for stretch
Rugae
Plasticity of smooth muscle
>increased tension increases radius and they remain proportionate: obey law of la place

Question 8

At what volume of urine do we have an awareness of a need to void?

Answer 8

150ml

Question 9

At what volume of urine do we have an urge to void?

Answer 9

300ml

Question 10

At what volume of urine do we experience pain?

Answer 10

600ml

Question 11

What are the origins of the sympathetic nerves to the bladder?

Answer 11

T10-L4

Question 12

What nerves give sympathetic innervation to the bladder?

Answer 12

Hypogastric

Question 13

What receptors do the hypogastric nerves act on?

Answer 13

B3 relaxes detrusor muscle

a1 tightens internal sphincter

Question 14

What NT is used in the hypogastric nerves?

Answer 14

NA

Question 15

What are the origins of the parasympathetic nerves to the bladder?

Answer 15

S2-S4

Question 16

What nerves give parasympathetic innervation to the bladder?

Answer 16

Pelvic plexus

Question 17

What NT is used in the pelvic plexus?

Answer 17

ACh

NO

Question 18

What receptors does the pelvic plexus act on?

Answer 18

Muscarinic M3 ACh
Contracts detrusor
Relaxes internal sphincter

Question 19

What are the origins of the somatic nerves to the bladder?

Answer 19

S2-4

Question 20

What nerve gives somatic innervation to the bladder?

Answer 20

Pudendal

Question 21

What NT is used in the pudendal nerve?

Answer 21

ACh

Question 22

What receptors does the pudendal nerve act on?

Answer 22

Nicotinic ACh

Contracts external sphincter

Question 23

What happens in the storage phase?

Answer 23

Low firing from stretch receptors in the bladder
Signals to spinal cord
Inhibit parasympathetic activity: relax detrusor muscle and contracts internal sphincter
Signals set to midbrain (pontine storage centre) to increase external urethral activity and decrease parasympathetic activity

Question 24

What happens in the voiding phase?

Answer 24

Relaxation of urethral sphincters
Contraction of detrusor muscle
Increased bladder pressure
Valsalva manoeuvre

Question 25

Where does increased firing of bladder afferents go to?

Answer 25

Rostal brain stem

Question 26

Where does stretch info from the bladder get processed?

Answer 26

Periaqueductal Gray and Pontine micturition centre | -gives sensation of bladder fullness

Question 27

What are the 2 stages of loss of voluntary micturition control after a spinal cord injury?

Answer 27

Areflexic | Hyperreflexic

Question 28

What happens during the areflexic stage?

Answer 28

Atonic bladder Spinal cord is isolated from the brain and can't sense full bladder Reflexes are absent below the level of the lesion Bladder loses tone and will leak uncontrollably

Question 29

What is the treatment for someone with atonic bladder?

Answer 29

Catheterisation | Prevents stretching and damage to bladder

Question 30

What happens during the hyperreflexic phase?

Answer 30

Automatic bladder Reflexes in sacral region of spinal cord are isolated from brain Bladder empties automatically when full due to spinal reflexes

Question 31

How can a patient with an automatic bladder control micturition?

Answer 31

Press on abdomen to initiate the reflex at an appropriate time