Repro Topic 4 - Bladder

Question 1

Describe the afferent and efferent pathways for control of bladder function

Answer 1

• Efferent
  
  • Sympathetic - hypogastric nerve (T12-L2)
  • Parasympathetic - pelvic nerve (S2, 3, 4)
• Afferent - pelvic, hypogastric and pudendal nerves from bladder wall
  
  • A delta (normal) and C (pathological) fibres

Question 2

How does urine retention lead to hydronephrosis?

Answer 2

1. Bladder filling, increased upper tract pressure
2. Ureters dilate, peristalsis lost, ureteric drainage dependent on gravity
3. Increasing pressure = decreasing renal function

Question 3

Describe the voiding phase of micturition

Answer 3

• Voluntary relaxation of external sphincter
• Pontine micturition relaxes internal first
• Parasympathetic action causes detrussor contraction, bladder empties
• Assissted by contraction of abdominal muscles - increases the pressure in the bladder

Question 4

What is the role of higher centres in the brain in the micturition reflex?

Answer 4

• Keep micturition reflex inhibited except when micturition is desired
• Contraction of external sphincter
• When time to urinate high centres send signals to sacral micturition centre which stimulates the micturation reflex
  
  • Coordinates: spino-bulbar-spinal reflex, detrussor contraction, urethral relaxation

Question 5

Describe the structure of the male urethra

Answer 5

• 15-20cm long, carries urine and semen
• 4 parts - pre-prostatic, prostatic, membraneous, spongey
  
  • Prostatic - prostatic and ejaculatory glands empty into
  • Membraneous - surrounded by external urethra sphincter
  • Spongey - through bulb and corpus spongeosum, ends at external urethral orifice, bulbourethral glands empty into

Question 6

Describe the venous drainage of the ureters

Answer 6

Follows arteries

Question 7

Describe the higher centres in the brain involved in micturition

Answer 7

• Pontine micturition (Barrington’s nucleus)
  
  • Dorsolateral pons, collection of neuronal cell bodies
  • Send axons via lateral columns to sacral micturition centre (intermediolateral nucleus and Onuf’s nucleus)

Question 8

Describe the structure of the walls of the bladder

Answer 8

• Rugae (folds) allow for expansion - volume can increase without pressure changing
• Mucosa - transitional epithelium, lamina propria
• Submucosa
• Detrussor muscle
• Adventitia

Question 9

Describe the process of the micturition reflex

Answer 9

• Bladder fills until it reaches critical pressure, stretch receptors activated, signals from bladder to spinal cord via sensory afferents (pelvic nerves)
• Activates autonomic spinal reflex (parasympathetic + sympathetic activity), can be overriden by higher centres in the brain
• Causes contraction of the detrussor muscle, at partial filling contractions relax spontaneously - allows more filling
• With continued filled reflexes become more frequent
• If signals from brain are stronger than voluntary contraction of the external sphincter micturition occurs
• If not, bladder fills further and further and reflex becomes stronger

Question 10

What is the effect of the parasympathetic efferent pathway on the bladder?

Answer 10

Contraction of detrussor muscle - micturition

Question 11

Describe the innervation of the ureters

Answer 11

Renal, testicular/ovarian and hypogastric plexus

Sensory fibres –> T11-L2

Question 12

Describe the arterial supply of the ureters

Answer 12

• Renal and testicular/ovarian arteries from the abdominal aorta
• Superior and inferior vesical arteries from the internal iliac artery

Question 13

List the stages of micturition

Answer 13

• Filling
• Micturition reflex
• Voiding

Question 14

List the functions of the bladder

Answer 14

• Store urine at low pressure (no sensation)
• Empty fully at socially convenient time
• Reciprocal contraction/relaxation

Question 15

Describe the arterial supply of the male urethra

Answer 15

• Prostatic - inferior vesicle from internal iliac artery
• Membraneous/spongey - bulbourethral from internal pudendal artery

Question 16

Describe the lymphatic drainage of the bladder

Answer 16

Vesical, external iliac, internal iliac and common iliac nodes

Question 17

What are the causes of bladder outflow obstruction?

Answer 17

• Men - prostatic hyperplasia
• Women - pelvic organ prolapse (pregnancy), pelvic masses
• Both -
  
  • Neurological disease - failure of relaxation of external sphincter
  • Bladder tumours, stones, urethral strictures (e.g. scar tissue)

Question 18

Describe the musculature of the bladder

Answer 18

• Lined by smooth muscle - detrussor
  
  • Spiral, longitudinal and circular layers
• Bundles around neck = internal urethral sphincter (involuntary)
• More distal = external urethra sphincter (after prostate in males) - voluntary, skeletal muscle, in ureogenital diaphragm
• Internal controlled by ANS, external by voluntary control

Question 19

Describe the innervation of the female urethra

Answer 19

Vesical plexus and pudendal nerve, visceral afferent nerve in pelvic splanchnic nerves

Question 20

What is the function of the urethra?

Answer 20

Drain urine from bladder to external opening (in perineum)

Question 21

Describe the lining of the male urethra

Answer 21

• Pre-prostatic, prostatic - transitional
• Membraneous, proximal spongey - pseudostratified columnar
• Distal spongey - stratified squamous

Question 22

Where is Onuf’s nucleus found? What is its function?

Answer 22

S2, 3, 4 - somatic, anterior horn

Maintains continence

Question 23

What is the function of the afferent pathway from the bladder?

Answer 23

Signals to brain when bladder is full

Question 24

Describe the gross anatomy of the bladder

Answer 24

• Hollow muscular organ - body, neck and apex
  
  • Neck connects to urethra
• Normal capacity - 400-500ml (can hold more - backflow risk)
• Held at neck by puboprostatic (male) or pubovescical (female) ligaments, attach to pubic symphysis
• Base is trigone, has ureteric openings, less mobile and more sensitive to pain

Question 25

Describe the structure of the female urethra

Answer 25

* 4 cm long (increased risk of UTI/incontinence e.g. due to pregnancy) * Opening external urethral orifice = vestibule * 2 mucous glands at distal end - Skene's glands

Question 26

What is the effect of the sympathetic efferent pathway on the bladder?

Answer 26

Causes relaxation of detrussor muscle - urine retention

Question 27

Describe the path of the ureters

Answer 27

* Begin abdominally as continuation of the renal pelvis, end in pelvic cavity where they drain into the bladder * Descend through abdomen, along anterior surface of psoas major, retroperitoneal * At sacroiliac joint cross pelvic brim into pelvic cavity * Run down lateral pelvic wall * Peirce lateral wall of bladder

Question 28

Describe the innervation of the male urethra

Answer 28

Prostatic plexus - parasympathetic, sympathetic + viseral afferent fibres

Question 29

What are the consequences of chronic urine retention?

Answer 29

* Upflow from bladder can cause irreversible kidney damage - hydronephritis * Usually only 1 kidney affected * Irreversible tubular atrophy if obstruction not recognised + corrected - blunting of papillae, interstitial fibrosis * Increased susceptibility to UTIs/urolithiasis (struvite) - stagnant urine

Question 30

Describe the arterial supply of the bladder

Answer 30

Superior and inferior vesical branches of the internal iliac artery + uterine/vaginal arteries in females

Question 31

How can the intactness of the sacral micturition reflex be tested?

Answer 31

Check the bulbocavernous reflex

Question 32

Describe the filling phase of micturition

Answer 32

Increasing volume of urine, walls stretch to accommodate, little increase in pressure (= compliance)

Question 33

Describe the lining of the female urethra

Answer 33

Proximal 2/3 = transitional epithelium Distal 1/3 = Stratified squamous epithelium

Question 34

Describe the blood supply of the female urethra

Answer 34

Arteries = Internal pudendal, vaginal and inferior vesical branches of vaginal arteries Veins follow arteries

Question 35

What is the function of the ureters?

Answer 35

Transport urine from the kidneys to the bladder

Question 36

How does spinal shock cause bladder dysfunction?

Answer 36

* Decreases excitability below injury * No somatic reflexes and flaccid muscle paralysis * Acontractile, areflexic bladder, sphincter functioning * Urine retention * Lasts days-months

Question 37

How is bladder dysfunction in spinal shock treated?

Answer 37

Catheter - suprapubic or clean intermittent self catheterisation

Question 38

What controls the micturition reflex?

Answer 38

Autonomic reflex under partial voluntary control

Question 39

How is the entry of the uterers of the bladder functionally beneficial?

Answer 39

Pierce lateral wall of bladder at oblique angle - one-way valve to prevent backflow

Question 40

List causes of bladder dysfunction

Answer 40

* Spinal shock * Multiple sclerosis * Neuropathic detrussor hyperreflexia e.g. in spina bifida * Parkinson's

Question 41

What is the function of the sacral micturition centre?

Answer 41

Parasympathetic, relaxation of sphincter, voiding

Question 42

Describe the venous drainage of the bladder

Answer 42

Vesical venous plexus, drains to the internal iliac vein

Question 43

Describe the structure of the ureters

Answer 43

* 2 bilateral thick tubes * 25cm long * Stratified transitional epithelium * Walls lined with smooth muscle, contracts to produce peristaltic waves, push urine to bladder

Question 44

Describe the venous drainage of the male urethra

Answer 44

Inferior vesicle vein, middle rectal vein, internal pudendal vein