Micturition

Question 1

Define micturition?

Answer 1

. The normal process of the passive storage
and active voiding of urine
. Includes storage phase as well as the
voiding phase.

Question 2

How is retrograde flow from the bladder into the ureters prevented?

Answer 2

. Retrograde flow prevented by the oblique angle of

entry through the bladder wall

Question 3

The bladder is under what kind of control?

Answer 3

Involuntary. (smooth muscle)

Question 4

The urethra is under what kind of control?

Answer 4

Urethra (voluntary an
Involuntary)
— Smooth muscle
— Skeletal muscle

Question 5

What is the detrusor muscle?

Answer 5

A network of smooth muscle fibres within the bladder

wall. Supplied by both sympathetic and parasympathetic fibres.

Question 6

What is the internal urethral sphincter?

Answer 6

. Thickening of the bladder
musculature
. Smooth muscle
. Supplied by sympathetic
supply

Question 7

What is the external urethral sphincter?

Answer 7

. Striated muscle fibres
. Under voluntary control
of somatic nervous
system

Question 8

What does the Parasympathetic supply

(cranio-sacral) to the bladder do?

Answer 8

Innervation — detrusor muscle
Neurotransmitter - ACh
Action — excitatory
Function — empty bladder

Question 9

What does the Sympathetic supply to the

detrusor muscle allow?

Answer 9

. Neurotransmitter — Norepinephrine
. Receptor - beta
. Action — inhibitory on skeletal muscle
fibres
. Function — allows bladder filling

Question 10

What is the detrusor reflex?

Answer 10

Increased vesicular pressure with filling achieves threshold resulting in contraction of the detrusor muscle involuntarily.

Question 11

What does the positive feedback of the detrusor reflex achieve?

Answer 11

Once it has started positive feedback cause contractions to continue until the bladder is fully emptied.

This occurs at the SC level all a passive.
process.

Question 12

The somatic motor supply outflows from S1-2 to form pudendal nerve it contains no synapses and Innervates the urethral skeletal muscle, specifically the External urethral sphincter. What function does this allow?

Answer 12

The retention of urine.

Question 13

Sympathetic supply to the internaI sphincter outflows from L1-4. It synapses at the caudal mesenteric ganglion and innervates the internal sphincter. What function does this allow?

Answer 13

Retain urine, increase urethral

tone

Question 14

What stimulates the micturition reflex in the voluntary state?

Answer 14

Intra abdominal pressure stimulates the micturition reflex in voluntary state.

Question 15

A-adrenergic blocker do what?

Answer 15

Decrease sphincter tone by inhibiting the stimulatory outflow from L1-4 to the internal sphincter.

Question 16

A-sympathomimetic does what?

Answer 16

Increase sphincter tone by increasing the stimulatory effect of outflow from L1-4.

Question 17

Skeletal muscle relaxants do what?

Answer 17

Decrease sphincter tone by inhibiting somatic supply from S1-2.

Question 18

Parasympathomimetic drugs do what?

Answer 18

Increase detrusor tone by stimulating parsympathetic fibres from S1-3.

Question 19

The function of Sympathetic and somatic nerves are to?

Answer 19

Retain urine.

Question 20

The function of parasympathetic nerves are to?

Answer 20

Void urine.

Question 21

Define incontinence

Answer 21

Incontinence is the lack of voluntary control of excretory functions.
Can occur alongside normal micturition or separate to
micturition.

Question 22

Define dysuria?

Answer 22

Difficult or painful passage of urine.

Question 23

Define stranguria?

Answer 23

Straining or hesitancy associated with urination.

Question 24

Define pollakuria?

Answer 24

Increased frequency of urination.

Question 25

Define nocturia?

Answer 25

The urge need to urinate over night.

Question 26

Define enuresis?

Answer 26

Unconscious leakage of urine during sleep.

Question 27

What clinical signs do animals with upper motor neurone (high spinal cord or brain dysfunction) damage show with regards to the bladder?

Answer 27

*Retained reflexes with increased tone because reflex arcs are not damaged. ``` . Reflexes being there but hyper excitable and increased tone. Won’t have voluntary urination as UMN lesion. . Bladder tone will be increased and urethral sphincter tone increase so will have a large volume of urine with a difficult to express bladder. ``` . Absent voluntary micturition . Increased urethral sphincter tone . High volume urinary retention . Development of automatic bladder

Question 28

What clinical signs do animals with lower motor neurone (Sacral spinal segment damage or pelvic plexus) damage show with regards to the bladder?

Answer 28

Low tone with areflexia due to sacral spinal or pelvic plexus damage. . Will see permanent leakage as sphincters all open with atonic bladder. Absence of voluntary micturition and absent detrusal reflex. ``` . Absent voluntary micturition . Atonic bladder . Atonic urethral sphincters . Absent detrusor reflex . Concurrent reduced perineal reflex and anal tone . Flaccid an easily expressed ```

Question 29

What congenital malformation would you expect to be associated with a constant dribble?

Answer 29

Ectopic ureters. If one goes in urethra and one in bladder will see constant dribble and Ureter normal micturition.

Question 30

What are some acquired abnormalities of lower urinary | tract?

Answer 30

— neoplasia — calculi —Trauma (e.g ruptured ureters can cause chemical peritonitis, scarring etc.)

Question 31

Reflex dyssynergia is what?

Answer 31

Initiation of detrusor reflex with reflex contraction of the urethral sphincter. You get initiation of detrusor reflex and rather than normal micturition reflexyou get a reflex contraction of urethral sphincter. So will see an animal that will strain and posture to urinate but there is not passage of urine. This can be dramatic and life threatening. Can get overfilling of bladder and rupture. Can catheterise the bladder.

Question 32

Sphincter mechanism incompetence?

Answer 32

A weak valve on the bladder that allows leakage of urine. Normal micturition and contiunous leakage of urine or leakage of urine when dog gets excited. More common in female dog because the effective length of sphincter in male urethra is longer. More common in large/giant breeds female More common in speyed female (hormonal influence involved in sphincter closer)

Question 33

What are some treatment strategies for sphincter mechanism incompetence?

Answer 33

— a adrenergic agonists (E.g phenylpropanolamine) Will tense up the urethral sphincter — Oestrogens — Surgery — culposuspension (you pull the bladder forward by putting sling of tissue bladder neck with effectively stretches the urethra increasing tone within smooth muscle)

Question 34

How is secondary detrusor muscle atony or decrease or absent tone in detrusor muscle so the bladder wont be able to void caused?

Answer 34

. Stretch injury . Most common cause is failure to treat animal beforehand when it has a urethral blockage. Overexpansion of bladder and detrusor muscle looses the ability to contract. . Detrusor muscle can repair overtime

Question 35

Urge incontinence is caused when?

Answer 35

— Micturition reflex initiated at low volume. — Bladder mucosa irritation. Commonest way to get it is cystitis.