(15) - Bladder I

Question 1

Answer 1

Question 2

Answer 2

no evidence of structural obstruction

Question 3

what do you need to know to solve this dog’s problem?

anatomy, need to know innervation

Answer 3

and now on to the hellish

Question 4

Anatomically, the Lower urinary tract consists of the urinary bladder and urethra, plus the caudal portion of each ureter, which tunnels through the bladder wall and is connected to the bladder neck and urethra

Question 5

(Functionally, the lower urinary tract consists of three components arranged in series (functional components are determined by their innervation)

1. the smooth muscle coat of the bladder apex and body

it expels urine, when activated by what kind of innervation?

2. Smooth muscle of the bladder neck and, in the case of females and male cat, the cranial urethra.

It provides tonic resistance, when contracted by what kind of innervation?

3. ? = urethralis muscle

It opposes sudden increases in abdominal/bladder pressure, and is used for what?

activated via what?

Answer 5

1. detrusor muscle

parasympathetic innervation (via the pelvic nerve)

2. smooth muscle sphincter

sympathetic innervation (via the hypogastric nerve)

3. striated urethral sphincter

voluntary continence

the pudendal nerve

Question 6

(The central nervous system ultimately controls the three functional components so they work synergistiaclly to store and void urine)

1. forebrain decides what?
2. pons - does what?
3. spinal reflexes do what?

Answer 6

1. when it is appropriate to urinate
2. inhibits sphincters and sustains detrusor during micturition
3. generate sphincter resistance during urine storage

Question 7

(THIS IS BID TYPE)

normal micturition entails coordinated actions of detrusor and sphincter musculature to enable complete emptying of the urinary bladder at appropriate times

Question 8

1. Can voluntary urination be emotionally motivated?
2. in neonatal kittens, micturition reflex can be triggered by doing what?

Answer 8

1. yes (marking)
2. licking the perineum

Question 9

Question 10

read pages 2-3 of notes

Question 11

(III. Filling and Storage)

(Bladder filling)

1. urine drains continuously from what?
2. Urine is collected by what?
3. Accumulated urine stretches pacemaker myocytes in the wall of the renal pelvis, triggering them to fire AP that result in what?
4. The end result is a peristaltic wave of smooth muscle contraction that does what?

Answer 11

1. the medullary surface of the kidney
2. the renal pelvis
3. increased intracellular [Ca] (which spreads amoung smooth muscle cells of the renal pelvis and ureter gap junctions)
4. propels a urine bolus along the ureter

Question 12

(III. Filling and Storage)

1. By passing obliquely through the bladder wall, the terminal segment of the ureter is normally closed or open? by what? to do what?
2. Each peristaltic wave must convey a bolus or urine into the bladder with sufficient force to do what?

Answer 12

1. closed by intravescial pressure to preclude urine reflux
2. to open the terminal intramural ureter

(Note: urinary continence, the ability to store urine without leakage, requires outlet resistance to exceeed intravesical pressure)

Question 13

(III. Filling and Storage)

(Bladder Storage - First Step)

1. initially, when bladder pressure is low, what of the urethral wall maintains outlet closure?

(Note: in quadrupeds, passive resistance is augmented when urine weight pulls the bladder cranially into the abdomen away from the urethra (Squatting to urinate shifts urine weight caudally against the urethral opening)

Answer 13

1. passive viscoelastic resistance (passive resistance is the result of mucosal enfolding, submucosal elastic fibers, and stratum spongiosum, particularly when the latter is filled with blood)

Question 14

(III. Filling and Storage)

(Bladder Storage - step 2)

1-2. As bladder volume approaches half-full, continued continence requires spinal sympathetic reflexes to do what two things?

Answer 14

1. contract the smooth muscle sphincter
2. inhibit spontaneous contraction of the detrusor

(These sympathetic reflexes involve afferent axons that run through the pelvic nerve to sacral spinal roots and efferent axons that come from lumbar spinal segments and travel through the hypogastric nerve)

Question 15

(III. Filling and Storage)

(Bladder stoarge: step 3)

1. To halt urine leakage during abrupt increases in intravescial pressure (when the tonic smooth muscle sphincter in breached), what contracts?

This involves a spinal reflex triggered by what?

Answer 15

1. the striated urethralis muscle

urine flow into the urethra

Both afferent and efferent axons run through the pudendal nerve and sacral spinal cord

(also the levator ani muscle reflexly contracts to support pelvic viescera when muscles of the abdominal wall contract to increase intra-abdominal pressure during running, jumping, etc.)

Question 16

(III. Filling and Storage)

1. the urethralis muscle is used for what kind of continence?
2. this is also the muscle that contracts during what?

Answer 16

1. voluntary continence (including abrupt cessation of urine flow)
2. male ejaculation

Question 17

(IV. Micturition)

1. As bladder volume expands (particularly during spontaneous waves of detrusor contraction and when compliance reaches its limit) mechanoreceptors sensitive to wall tension generate what?
2. Afferent axons travel through the pelvic nerve to what?
3. they synapse on interneurons to generate what?
4. they also synapse on projection neurons that do what?

Answer 17

1. increased afferent activity
2. the sacral spinal cord
3. continence related spinal reflexes
4. relay wall tension to the brain

Question 18

(IV. Micturition)

1. What senses bladder awareness/fullnes/urgency along with cognitive interpretations of surroundings and emotional status?
2. These perceptions are factored into a decision either to do what or what?

Answer 18

1. the forebrain
2. inhibit or initiate micturition

(the latter involves the onset of behavior to facilitate micturtion (movement, posture, abdominal press) and neural instructions to the pons)

Question 19

(IV. Micturition)

1. What switches from continence to micturition?

Answer 19

1. the pons

(Descending tracts from the pontine micturition center inhibit neurons to smooth and straited sphinceter and excite parasympathetic preganglionic neurons to the detrusor)

and then

Detrustion contraction boosts bladder wall tension and intravesical pressure within the closed bladder. The detrusor pulls open the bladder neck and intravesical pressure forces urine into the relaxed bladder neck and urethra. Eventually, wall tension and mechanoreceptor activity delcine along with bladder volume, but brain facilitation sustains detrusor contraction until the bladder is virtually empty.)

Question 20

Clinical Note

1-2. Spinal lesions that damage descending tracts from the pons impair normal micturition by doing what two things?

Answer 20

1. reducing sustained detrusor contraction
2. producing detrusor-sphincter dyssnergy

(as a result, smooth and striated sphincter reflexes are not adequately inhibited during attempted micturition)

the chronic result is detrusor hypertrophy and frequent cystitis due to bacterial contamination fo retained urine. The same dyssynergy impedes attempts to macually empty the baldder in paraplegic patients)

Question 21

Answer 21

it’s not always…

he didn’t say which one for dogs

like to save urine for marking

Question 22

Answer 22

the answer is B