the lower urinary tract Flashcards

1
Q

what is the urinary tract

A

ureters
urinary bladder
urethra

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2
Q

how does urine exit the kidneys

A

final mod in cd
travels through cd deep into inner medulla
exits art top of renal pyramid - aka renal papilla
site of nephrotoxicity

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3
Q

how does urine leave the kidney into renal pelvis and ureter

A

minor and major calyces lead to renal pelvis
fluid deposition into renal pelvis, stretches smooth muscle
distension triggers peristaltic contractions at hilum
fluid moves down ureter into pulses to bladder

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4
Q

what is the structure of the ureters

A
tubes 30cm long 
mucosal layer - transitional epithelium (3-8 cells thick, impermeable to urine)
supported by SM 
inner longitudinal 
outer circular 
extra outer L
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5
Q

what is the function of the ureter

A

dilation of renal pelvis generatrews action potential from pacemaker cells at hilum
peristaltic waves 1-6/min
can be mod by NS

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6
Q

how does peristalsis work in the ureters

A

peristaltic contraction consists off successive waves of contraction and relaxation of L and C muscle
L contrast followed by C
then relax L and C contract to push against bolus
slow but progressive movement
aka vermiculation

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7
Q

how does urine enter the bladder

A

ureters attach to posterior wall of bladder
pass into wall at oblique angle for 2/3cm
slit like
helps to stop back flow

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8
Q

structure of the bladder

A

hollow muscular organ, fundus and neck
other detrusor muscle layer - L and C muscle
inner mucosal layer - transitional epithelium, folded into rugue when bladder empty, highly elastic

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9
Q

function of the bladder

A

temp storage of urine
up to 1L
stimulated to contract by PNS

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10
Q

what is the trigone

A

triangular area bounded by openings of ureters and entrance to urethra
acts as a funnel to channel urine to neck of bladder

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11
Q

what is the internal urethral sphincter of the bladder

A

loop of smooth muscle
convergence of detrusor muscle
involuntary
normal tone keeps neck and urethra free of urine

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12
Q

what is the external urethral sphincter

A

circular band of skeletal muscle where urethra passes to urogenital diaphragm
acts as a valve with resting muscle tone
voluntary

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13
Q

how does the urinary tract end in females

A

urethra opens via external urethral orifice located between vagina and clitoris
shorter in females
external sphincter not as well developed - incontinence after childbirth

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14
Q

how does the urinary tract end in males

A

urethra passes through prostate gland and through urogetial diaphragm and penis
longer urethra
prostate gland enlarges (50% >60yo)
prostate cancer - commonest in older men

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15
Q

what is micturition

A

2 stage process
bladder progressively fills until pressure in bladder at threshold
elicits micturition reflex, produces a conscious desire to urinate

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16
Q

what controls micturition

A

autonomic
inhibited by higher centres in brain and facilitated by cortical centres in brain (initiate and relax external sphincter)

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17
Q

how does the bladder fill

A

1ml/min at normal levels of hydration
intravesical pressure inc
periodic reflex contractions of short duration occur above 200ml
partially full - contractions relax spont
inc full - more freq, intense and longer
desire, discomfort, urgency

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18
Q

bladder and sphnicter inneratiobn

A

L2 hypogastric nerve - symp invol control
S2,3,4 - pelvic nerve PS invol
pudenal nerve - somatic, vol
HG and Pu inhibit micturition and facilitated by pelvic

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19
Q

what is the guarding reflex

A

bladder fills up, distension, stretch receptors via pelvic nerve, HG nerve (relax and red excitability of bladder detrusor muscle, constrict int sphincter)
ext sphincter held closed by pu nerve
promote continence

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20
Q

what is the micturition reflex

A

SR cont to stim pelvic nerve (detrusor contract, relax internal sphincter)
micturition contractions
full bladder sensation to thalamus and cerebral cortex to inc desire to urinate
at ap time vol relax ext sphincter via pu nerve, micturition, lower diaphragm, contract ab muscles, open int sphincter

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21
Q

how can paraplegia disrupt micturition

A

complete severing of nerve inputs from cerebral cortex
micturition reflex return but no cortical control
periodic unannounced bladder emptying (automatic bladder)

22
Q

how can partial spinal cord damage with loss of inhibitory descending signals affect micturition

A

freq urination as excitatory impulses from cerebral cortex remain unopposed
uninhibited bladder

23
Q

how can crush injuries of the dorsal roots affect micturition

A

afferent nerve destruction - mic reflexes loss despite effects system
fills to capacity and overflows drowse (overflow incontinene - atonic bladder)

24
Q

how do infants bladders work

A

lack voluntary control until corticospinal connections are established

25
Q

problems with micturition reflex

A

can be lost due to stroke, Alzheimers, cerebral cortex issues or hypothalamus eg tumour
bladder sphincter muscles lose tone eg preg (incontinence)
urinary region in males - enlarged prostate gland compressing urethra and restricts flow

26
Q

functional classifications of micturition reflex issues

A

failure to store urine - incontinence
failure to empty bladder - retention
due to dysfunction or outlet of urine or brain/nervous control

27
Q

main types of urinary incontinence

A

loss of sensory nerves - injury (fills to capacity, no SR signal, overflow)
invol contractions - injury (urge incontinence/inc freq)
heightened urge incontinence - sensitive bladder (spicy food (capsaicin), caffeine or choc (xanthines), citrus, carbonated bev, laughter)

28
Q

how is the pelvic nerve involved in the bladder

A

Ace release
promote micturition via detrusor muscle contraction, involuntary sphincter relaxation
incontinence

29
Q

what drugs can stop incontinence

A

Muscarinic AchR antagonists (anticholinergics)

oxybutinin

30
Q

unwanted effects of anticholinergics

A

dry mouth, blurred vision, palpitations, drowsiness, facial flushing

31
Q

what are tricyclic anti depressants

A

imipramine - short term, low dose for nocturnal enuresis in child
side effects - behaviour issues on withdrawal

32
Q

mechanisms of drugs used for incontinence

A

anti-ach and direct muscle relaxant effects on bladder also inhibit NA uptake and serotonin inc
duloxetine - inc s and na (mod/sev stress incontinence)
demospression - ADH analogue, can be used for kids
mirabegron - B2 receptor agonist (selective) for overactive bladder
purified bovine collage implants

33
Q

how to treat urinary retention

A

catheterisation
surgery
chronic - pharmacological or surgical

34
Q

how does the hypogastric nerve interact with the bladder

A

NA released to reduce micturition

35
Q

drugs used for urinary retention

A

a1a adrenoreceptor stim by NA

site for drug action on prostate

36
Q

how to a-adrenergic blocking drugs work for urinary retention

A

antagonist in bladder neck
relax to inc flow rate
eg -zosin drugs

37
Q

unwanted effects of a-adrenergic blocking drugs

A

can reduce BP (if already on antihypertensive drugs or with postural hypotension)
hypotension, drowsiness, depression, headache, dry mouth, GI disturbances

38
Q

how to parasympathomimetics (choline esters) treat urinary retention

A

agonist action on ach receptrs
inc contraction of detrusor muscle
limited role - catheters used over them
eg bethanecol

39
Q

cautions of PSMetics

A

care/avoid in cardiac patients

avoid in GL ulcers, asthma, hypotension, epilepsy, Parkinson’s, pregnancy

40
Q

unwanted effects of PSMetics

A

nausea, vomitting, colic, bradycardia, blurred vision, sweating

41
Q

other treatments for urinary mentions

A

inhibit act breakdown and promote incontinence

inhibitors of androgen synthesis - prostate hyperplasia

42
Q

how to treat urinary retention

A

catheterisation
surgery
chronic - pharmacological or surgical

43
Q

how does the hypogastric nerve interact with the bladder

A

NA released to reduce micturition

44
Q

drugs used for urinary retention

A

a1a adrenoreceptor stim by NA

site for drug action on prostate

45
Q

how to a-adrenergic blocking drugs work for urinary retention

A

antagonist in bladder neck
relax to inc flow rate
eg -zosin drugs

46
Q

unwanted effects of a-adrenergic blocking drugs

A

can reduce BP (if already on antihypertensive drugs or with postural hypotension)
hypotension, drowsiness, depression, headache, dry mouth, GI disturbances

47
Q

how to parasympathomimetics (choline esters) treat urinary retention

A

agonist action on ach receptrs
inc contraction of detrusor muscle
limited role - catheters used over them
eg bethanecol

48
Q

cautions of PSMetics

A

care/avoid in cardiac patients

avoid in GL ulcers, asthma, hypotension, epilepsy, Parkinson’s, pregnancy

49
Q

unwanted effects of PSMetics

A

nausea, vomitting, colic, bradycardia, blurred vision, sweating

50
Q

other treatments for urinary mentions

A

inhibit act breakdown and promote incontinence

inhibitors of androgen synthesis - prostate hyperplasia