Movement of Urine / Micturition

Question 1

upper urinary tract

Answer 1

calyces
pelvis
ureteres

Question 2

bladder

Answer 2

stores urine under low pressure

expels under high pressure

Question 3

urethra

Answer 3

way to expel urine

has sphincter

Question 4

internal sphincter

Answer 4

smooth muscle (involuntary)

Question 5

external sphincter

Answer 5

skeletal muscle (voluntary)
-where urethra joins bladder

Question 6

afferent pathways/

Answer 6

sense fullness or pain

Question 7

fullness?

Answer 7

pelvic splanchninc to posterior column

S2-S4

Question 8

pain?

Answer 8

hypogastric plexus to anteriolateral column

S2-S4

Question 9

reflex arc?

Answer 9

S2-S4

from bladder and urethra

Question 10

bladder reflex arc?

Answer 10

sacral detrusor nucleus

-bladder fullness

Question 11

urethra reflex arc?

Answer 11

sacral pudendal nucleus

back to voluntary sphincter (external)

Question 12

parasympathetic fibers

Answer 12

sacral micturition centers S2-S4 (pelvic nerve)
-stimulate detrusor muscle
inhibits contraction of internal sphincter

tries to push fluid out of bladder

Question 13

sympathetic fibers

Answer 13

hypogastric nerve
inhibits detrusor constriction

constricts internal sphincter

Question 14

somatic fibers

Answer 14

voluntary - pudendal nerve

constrict external sphincter

Question 15

hypogastric nerve

Answer 15

sympathetic T10-L2

Question 16

pelvic nerve

Answer 16

parasympathetic S2-S4

Question 17

pudendal nerve

Answer 17

voluntary somatic fibers S2-S4

Question 18

barringtons center

Answer 18

pontine micturition center
-locus ceruleus of pons

descending impulses opposing PS outflow

coordinates activity of bladder and urinary sphincter

bladder fills to certain point and overcomes control

Question 19

movement of urine in urinary tract?

Answer 19

peristalsis

ureters have PS and S fibers

PS stimulation increases peristalsis
-increased urine delivery to bladder

S stimulation does opposite

Question 20

basal cystometrogram

Answer 20

volume versus pressure graph

not large increase in pressure because of bladder elasticity

micturition contraction around 200 mL volume

Question 21

micturition contractions

Answer 21

begin around 200 mL volume

-

Question 22

as radius increases?

Answer 22

wall tension increases

T = P x r / 2

activates the bladder stretch activated

• afferent to micturition center
• activates PS

higher center in brainstem - can suppress PS impulses up to certain point

Question 23

around 400 mL

Answer 23

no more inhibition of PS impulses

PS stimulates bladder contraction and inhibits internal sphincter

Question 24

after urine enter posterior urethra?

Answer 24

sensory impulses inhibit somatic nerve
-relaxes external sphincter

bladder falls in on itself pushing the urine out

Question 25

sacral micturition center

Answer 25

in spinal cord

Question 26

when can’t hold any longer

Answer 26

urine in posterior urethra

Question 27

atonic bladder

Answer 27

aka flaccid neuropathic bladder

destruction of sensory input from baldder to sacral cord
-diabetes, crush injury, syphilis, MS

stretch info no longer transmitted
-no more contractions

fills to capacity (overflow incontinence)
-distended and thin walled

Question 28

denervated bladder

Answer 28

aka hypertrophic areflexic bladder

destruction of both afferent and efferent fibers between bladder and cord

initial detrusor contraction ceases, flaccid bladder, distended

later, detrusor regains spontaneous activity

• bladder shrinks
• muscle wall hypertrophies

Question 29

automatic bladder

Answer 29

aka spastic neuropathic bladder

damage above sacral region
-no longer have brain communication

acute - spinal shock, suppress micturition reflex
-leads to flaccid bladder

reflex gradually recovers and becomes exaggerated
-results in spasticity (control by brain is lost)

Question 30

uninhibited neurogenic bladder

Answer 30

aka autonomic dysreflexia

destruction of tracts carrying inhibitory impulses from brain

facilitatory inputs in tact, micturition center continually stimulated

micturition activated by small amounts of urine

detrusor hypertrophies
bladder capacity reduced

Question 31

urinary tract infection

Answer 31

bladder and urethral irritation

uninhibited contraction of detrusor muscle with facilitation of micturition reflex

urinary frequency and leakage