Bladder And Urethra

Question 1

How much liquid can the bladder hold?

Answer 1

400-500mls

Question 2

What ligament holds the neck of the bladder in place?

Answer 2

Puboprostatic ligament in men

Pubovesicular ligament in women

Question 3

What ligament extends from the top of the bladder?

Answer 3

The median umbilical ligament

Question 4

What are the three layers of muscle found in the detrusor muscle?

Answer 4

Longitudinal (outer)
Circular
Spiral (inner)

Question 5

What factors contribute to internal urethral closure?

Answer 5

Muscular occulsion by rhabdosphincter
Transmission of abdominal pressure to proximal urethra 
Mucosal surface tension
Anatomical configuration at bladder neck
Submucosal vascular plexus 
Elasticity and length of urethra

Question 6

Do women have an internal urethral sphincter?

Answer 6

No anatomically, but they do have a physiogical mechanism

Question 7

What’s the venous drainage for the bladder?

Answer 7

A rich venous plexus that drains the the internal iliac veins

Question 8

Where does the lymphatic drainage for the bladder drain to?

Answer 8

Vesical, external iliac, internal iliac and common iliac lymph nodes

Question 9

What receptors play a role in micturition?

Answer 9

Muscarinic (M3) and B3 receptors on the detrusor muscle
Alpha-1 receptor found on the internal urethral sphincter
Nicotinic content receptor on the external urethral sphincter

Question 10

Which parts of the CNS are used during micturition?

Answer 10

Sacaral and thoracic nuclei

Pontine and micturition centres in the brain

Question 11

Name the three efferent nerves and which nerve fibres they contain.

Answer 11

From the sacral region arises the pudendal nerve, which contains somatic nerve fibres
From the sacral region arises the pelvic nerve, which contains sympathetic nerve fibres
From the thoracic region arises the hypogastric nerve, which contains parasympathetic nerve fibres

Question 12

What hormone does the pelvic nerve release, which receptor does it bind to and what does it stimulate?

Answer 12

It releases ACh, which binds to the M3 receptor and stimulates contraction of the detrusor muscle

Question 13

What hormone does the hypogastric nerve release, which receptor does it bind to and what does it stimulate?

Answer 13

The hypogastric nerve releases noradrenaline, which binds to two receptors

• the B3 receptor stimulating the relaxation of the detrusor muscle
• the alpha-1 receptors, stimulating the contraction of the internal urethral sphincter

Question 14

What happens to the hypogastric nerve on the way to the bladder (why does it release noradrenaline, not ACh)?

Answer 14

It synapses with a ganglion, ACh is released from the pre-ganglionic fibres to stimulate the post-ganglionic fibres, which continue on the the bladder and release the post-ganglionic hormone NA.

Question 15

What hormone does the puedendal nerve release, which receptor does it bind to and what does it stimulate?

Answer 15

The puedendal nerve releases ACh which binds to the Nicotinic receptor, stimulating the external urethral sphincter

Question 16

When are the somatic and sympathetic nerves active?

Answer 16

Somatic - when we want to hold out urine, so the hormone is firing all the time
Sympathetic - all the time we are not urinating

Question 17

Which response (parasympathetic or sympathetic) is responsible for holiday in our urine?

Answer 17

The sympathetic

• fight or flight
• can’t pee if your running like hell

Question 18

What is the name of the single afferent nerve from the bladder?

Answer 18

The afferent pelvic nerve

Question 19

What does the afferent nerve do when the bladder is empty?

Answer 19

Sends slow impulses to Onuf’s nucleus in the sacral region

Question 20

What happens to the signal for an empty bladder when it reaches the sacral region?

Answer 20

It travels up to the hypogastric nerve in the thoracic region
- stimulates the contraction of urethral sphincter and relaxation of detrusor muscle
It carries on up to the pons so the brain knows we have an empty bladder
- pons sends stimulating messages down to hypogastric
- pons sends inhibitory messages down to the pelvic nerve
- sometimes sends stimulators messages to the puedendal nerve

Question 21

What happens to the afferent pelvic nerve when the bladder is full?

Answer 21

It senses the stretched bladder and sends faster impulses down to Onuf’s nucleus in the pelvic region.

Question 22

What happens to the message for a full bladder when it reaches the spinal cord

Answer 22

The messages travel so fast up the spinal cord the bypass the hypogastric nerve and arrive at the micturition centre
The neurons in the centre are stimulated
- inhibits the hypogastric nerve and pudendal nerve (if we allow)
- stimulates the pelvic nerve

Question 23

What is the gating theory?

Answer 23

The restriction of the transmission of the messages from the afferent pelvic nerve
- Protects the parasympathetic fibres from afferent input until a threshold is reached

Question 24

How can the bladder keep contracting until it is empty?

Answer 24

Positive feedback mechanism

Question 25

What type of brain matter is the micturition centre located in?

Answer 25

Intermediolateral grey

Question 26

Which neurological conditions can cause abnormal bladder and sphincter function?

Answer 26

Spinal cord injury MS Neuropathic detrusor hyperreflexia Parkinson's disease

Question 27

What is spinal shock and what does it cause?

Answer 27

Period of decreased excitability at and below a signal cord injury. Causes absent somatic reflexes, flaccid muscle paralysis and a decrease in autonomic activity - in relation to the bladder, it is acontractile and areflexic with functional sphincters - leads to urine retention

Question 28

What is the bulbocavernosus reflux, and what does its absense mean?

Answer 28

It's the contraction of the anal sphincter most people get when their glans/clitoris is pulled on - its presence indicates that the sacral micturition centre is intact

Question 29

What's autonomic dysreflexia?

Answer 29

Exaggerated sympathetic activity in response to stimulus below the level of a spinal cord injury - decreased blood pressure and heart rate - sweating above lesion - vasoconstriction below

Question 30

What is detrusor hyperreflexia?

Answer 30

Bladder overactivity in a patient with an underlying neurological condition (Parkinson's or MS) - High pressure can cause hydronephrosis - M3 receptor blockers are best treatment

Question 31

List the causes of bladder outflow obstruction.

Answer 31

``` Enlarged prostrate (male) Pelvic organ prolapse, pelvic masses (women) Neurological disease Bladder tumours Bladder stone Urethral strictures ```

Question 32

What are the pathological consequences of bladder outflow obstruction?

Answer 32

Increased irritability Hydronephrosis Acute and chronic retention

Question 33

What is chronic retention of urine?

Answer 33

Painless retention of over 300mls of urine

Question 34

What two groups are chronic retention separated into?

Answer 34

HPCR - residual volume remains at a pressure higher than the intra-abdominal pressure after urination (associated with hydronephrosis) LPCR

Question 35

What is the pathophysiology of the upper urinary tract dilation in chronic retention?

Answer 35

Diuresis and bladder filling cause an increase in upper tract pressure Dilation of ureters leads to loss of peristalsis and ureteric drainage becomes reliant on gravity Associated with - hypertension - peripheral oedema

Question 36

Why does diuresis occur?

Answer 36

Patients with prolonged diuresis are unresponsive to ADH | Sodium reabsorption has been impaired for too long

Question 37

How is chronic diuresis managed?

Answer 37

``` Strict hourly urine output Daily weights U+Es BP (orthostatic hypotension) Most don't need volume replacement ```