MET PBL 8

Question 1

what does the lower urinary tract contain

Answer 1

ureters
bladder 
urethra 
internal sphincters
external sphincters

Question 2

what muscle are the structures of the lower urinary tract made out of

Answer 2

smooth muscle expect the external urethral sphincter which is striated

Question 3

describe the pathway of the ureters

Answer 3

• They pass over the pelvic brim at the bifurcation of the common iliac artery.
• Curves medially into the iliac spines and enter the bladder at posterosuperior angles

Question 4

what is the purpose of the angle that the ureters enter the bladder

Answer 4

o Rising pressures during micronutrition closes these orifices to prevent reflex.

Question 5

what propels urine into the bladder

Answer 5

peristalsis

Question 6

describe the trilayered wall of the ureters

Answer 6

o Transitional epithelial mucosa.
o Smooth muscle muscularis.
o Fibrous connective tissue adventitia.

Question 7

what is the nerve supply of the ureteres

Answer 7

• Visceral afferents enter at spinal levels T11-L1/L2.

Question 8

describe how the ureter nerve supply changes

Answer 8

• Pain (Ureter/Kidney Stones)
o Referred along ilioinguinal and Iliohypogastric nerves (L1).
 As stone descends patient may start to feel pain over groin.
 Because of changing nerve segments (pain referred to genitofemoral (L1/L2).

Question 9

where does the bladder lie

Answer 9

Lies retroperitoneally on the pelvic floor (posterior to pubic symphysis

Question 10

how is the bladder connected to the umbilicus

Answer 10

median umbilicus via the median umbilical ligament

Question 11

what is the trigone in the bladder

Answer 11

smooth muscle between the ureters and urethra

Question 12

what is the name of the muscle in the bladder

Answer 12

detrusor

Question 13

describe the histological make up of the bladder

Answer 13

Detrusor
• Muscular wall of the bladder.
o Empty: mucosa is thrown into folds.

• Transitional epithelium (cuboidal to columnar).
o Dome/umbrella cells that maintain impermeability to epithelium.

Question 14

what does the stress relaxation compliance property of the bladder allow

Answer 14

Stress-Relaxation/Compliance Property: enables detrusor to expand when filling (without consequent rise in intra-vesicular pressure

Question 15

what do the urethras do

Answer 15

drain urine that is in the bladder

Question 16

describe the female urethra

Answer 16

Females:

• urethra tightly bound to anterior vaginal wall.
• A lot shorter: more risk of UTI. Females,
• no IUS.

Question 17

describe the male urethra

Answer 17

• Intramural: (pre-prostatic).
• Prostatic: contains ejaculatory ducts
• Intermediate: penetrates perineal membrane (surrounded by EUS)
• Spongy: final part of the corpus spongiosum of penis.

Question 18

where does the prostate gland lie

Answer 18

• lies just beneath the bladder
• adjacent to the rectal wall
• partially surrounds the top of the urethra

Question 19

what does the prostate gland do

Answer 19

Makes semen with seminal vesicle.

Question 20

what can enlargement of the prostate gland cause

Answer 20

it can compress the urethra

Question 21

describe the innervation of the bladder

Answer 21

• Autonomic innervation (hypogastric nerve).
• Post-ganglionic pelvic parasympathetic nerves.

o Release acetylcholine which stimulate muscarinic M3 receptors that cause contraction

Question 22

describe the innervation of the internal urethral sphincter

Answer 22

Autonomic innervation.
o Post-ganglionic hypogastric sympathetic nerves and cause contraction

 Releases noradrenaline onto alpha 1 adrenergic receptors

Question 23

describe the innervation of the external urethral sphincter

Answer 23

• Somatic innervation (pudendal nerve).
o Release acetylcholine which stimulates nicotinic receptors on striated muscle.

• Pelvic afferent nerves detect stretch of the bladder wall and convey impulses to the sacral spinal cord and brain.

Question 24

what are the 3 mechanisms involved in micturition

Answer 24

storage phase
inhibition of diuresis
micturition reflex

Question 25

describe the storage phase

Answer 25

• Sympathetic efferents (STOPS PEE)
o Maintain tonic contraction in IUS.
o Inhibition contraction of detrusor muscle: beta 3

Question 26

describe the inhibition of diuresis

Answer 26

• Pelvic visceral afferents (S2-S4) signal to to the sacral spinal cord. Synapse and travel to the micturition centre. If not socially acceptable:
o Tightening of EUS (voluntary)
o Inhibition of contraction of detrusor

Question 27

describe the micturition reflex

Answer 27

• Inhibition of somatic efferents (pudendal nerve) and sympathetic efferents (hypogastric nerve) by interneurons that travel from micturition centre.
o Leads to relaxation of detrusor and external urethral sphincter

• Stimulation of parasympathetic efferents (PERMITS PEE)
o Stimulate detrusor muscle to contract.

Question 28

describe what happens to the bladder in children

Answer 28

In Children: in age 2-3 descending circuits have matured enough to override spinal reflex initiated urination.
• Briefly, visceral afferent impulses are transmitted to the higher brain centres, provide conscious awareness of bladder fullness. Can then consciously inhibit urination

Question 29

describe what urine culture and serum urea and creatinine is tested for

Answer 29

• Baseline test for infection (due to stasis of urine)/kidney damage due to back pressure

Question 30

why is a digital rectal examination do

Answer 30

• Allows a doctor to check the prostate by inserting finger into rectum.
o Irregular rather than smooth surface = possibility of malignancy.

Question 31

why is a PSA blood test do

Answer 31

• Prostate secretes PSA normally (involved in liquefying semen).
• Enlarged = a raise in PSA levels.
o If this is significant: rise in PSA suggest a biopsy should be considered for prostate cancer.

 NOTE: normal PSA does not rule out possibility of cancer.
 PSA can also increase when prostate is infected/inflamed.

• PSA levels generally increase with age.
o PSA >4 in younger people should be further investigated
o Later PSA >10 may be acceptable.

Question 32

what does urinary flow test measure

Answer 32

• Measures the maximum rate of urine flow.

Question 33

what does the post void residual volume test measure

Answer 33

• Measures if there is urine that remains in the bladder after urination.
o If high = evidence for that there is bladder outflow obstruction.
 If chronic retention, post-micturition volume can be 1.5 litres or more.
• Indicative of chronic renal failure.

• Measured through ultrasound/catheter.
o NOTE: care must be taken. If there is chronic retention/renal failure an insertion of a catheter and therefore possible relief of obstruction = massive diuresis and severe/potentially lethal problems maintaining fluid balance.

Question 34

what does a trans rectal ultrasound measure

Answer 34

• Measures prostate size and anatomical shape.

Question 35

what does a prostate biospy do

Answer 35

• Helps diagnose/role out prostate cancer.

o Done when PSA is high or irregularity in the DRE.

Question 36

explain the enlargement of the prostate gland

Answer 36

• Aways occurs within men over 60 (prostate gradually enlarges after age of 50).
o By 70  8/10 men will have an enlarges prostate.
• It is therefore normal to have a benign enlargement of the prostate

Question 37

when does the prostate start to enlarge

Answer 37

gradually enlarges after the age of 50

Question 38

explain the symptoms

Answer 38

• = distorts the urethra and obstruct bladder outflow.
o Leads to hypertrophy of bladder to overcome obstruction and void urine.
 Hyperplasia affects glandular/connective tissue.
 Eventually bladder dilates and the muscle fails as it cannot generate enough pressure.

• = impairs vesico-ureteric junction (causing reflux of urine).
o Results in hyronephrosis and chronic renal failure.

Question 39

explain how tamsulosin works

Answer 39

Medical Treatment
Tamsulosin: alpha adrenergic receptor blocker: relaxes the smooth muscle of the IUS.
• Opposes restriction on bladder neck outlet.

Question 40

explains how finasteride works

Answer 40

• Competitive inhibitor of 5alpha-reductase, which is the enzyme involved in the conversion of testosterone to dihydrotestosterone.
o Dihydrotestosterone is responsible for prostatic growth and enlargement.
• Therefore, finasteride decreases prostatic volume with an increase in urine flow.

Question 41

describe the different zones of the prostate and what pathology occur there

Answer 41

Transitional Zone: 5-10%. Surrounds the prostatic urethra. Site of BPH.

Central Zone: 25%. Surrounds the ejaculatory ducts.

Peripheral Zone: 60-65%. Most prostatic carcinomas occur here (70%).

Question 42

what are the zones of the prostate

Answer 42

transitional zone
central zone
peripheral zone

Question 43

what happens to the detrusor when the bladder is emptied

Answer 43

it is thrown into folds

Question 44

what provides voluntary control to the external urethral sphincter

Answer 44

the pudendal nerve S2-S4

Question 45

describe the basic mechanisms of micturition

Answer 45

Urine accumulation causes distension of bladder wall.

This activates stretch receptors in the wall.

Visceral afferents convey impulses to the sacral spinal
cord.

Interneurones excite parasympathetic nerves and
inhibit sympathetic nerves.

This results in detrusor contraction and IUS relaxation.

Question 46

What is responsible for prostate enlargement

Answer 46

o Dihydrotestosterone is responsible for prostatic growth and enlargement.

Question 47

3 constrictions of the ureter

Answer 47

uro-pelvic junction (renal pelvis just below)
pelvic brim
vesico-ureteric - (goes into the bladder)