Session 8 - Micturition and incontinence Flashcards Preview

Semester 3 - Urinary > Session 8 - Micturition and incontinence > Flashcards

Flashcards in Session 8 - Micturition and incontinence Deck (70)
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1

Give the three main parts of the bladder

• Body
• Trigone
• Neck

2

Give the histological layers of the bladder wall

MUCOSA
• Transitional epithelium
• Lamina propria
• Submucosa
NOT MUCOSA
• Detrusor muscle
• Adventiia

3

What is the body/fundus of the bladder?

• Temporary store of urine

4

What is the trigone?

• Ureteric orifices and internal urethral orifice are at the angles of a triangle

5

What is the neck of the bladder?

• Connects the bladder to the urethra

6

Outline the structure of the detrusor urinae muscle

• Made from a meshwork of muscle fibres in roughly 3 layers
○ Inner longitudinal
○ Middle circular
○ Outer longitundinal

7

Why does the bladder have three layers of muscle?

• Arrangement of muscle gives the bladder strength regardless of direction it is being stretched in

8

What is detrusor muscle supplied by?

• Autonomic nervous system, not under voluntary control

Spinal nerve supply is bilateral

9

What is the internal urethral sphincter?

• Continuation of the detrusor muscle and made of smooth muscle
• Physiological sphincter at the bladder neck

10

What is a physiological sphincter?

• A sphincter which is indistinguishable from surrounding tissue at autopsy

11

What is the primary muscle of continence?

• Internal Urethral Sphincter

12

What is the external urethral sphincter

• Anatomical sphincter
○ Localised circular muscle thickening to facilitate action

13

What is the external urethral sphincter derived from?

• Pelvic floor muscles

14

What type of muscle is the external sphincter?

• Skeletal muscle under somatic, voluntary control
• Contracts to constrict urethra and hold in urine

15

What are the two innervations of the detrusor?

• Parasympathetic
• Sympathetic

16

Outline the parasympathetic innervation of the detrusor

• Pelvic nerve (S2-S4)
• Ach - M3 receptors

Contraction

17

Outline the sympathetic innervation of the detrusor?

• Hypogastric nerve (T10-L2)
• NA -> B3 receptors
• Relaxation

18

What is the innervation of the internal urethral sphincter?

• Sympathetic
• Hypogastric nerve (T10 - L2)
• NA -> a1 receptors
• Contraction
• Parasympathetic
• Pelvic nerve

19

What is the innervation of the external urethral sphincter?

• Somatic
• Pudendal nerve (S2-S4)
• Spinal motor outflow from Onof's nucelus of the ventral horn of the spinal cord
• Ach -> Nicotinic teceptor
• Contraction

20

What are the four main functions of the nervous system in relation to the bladder?

• Provide sensation of bladder filling and pain
• Allow the bladder to relax and accomodate to increasing volumes of urine
• To initiate and maintain voiding so bladder empties completely, with minimal residual volume
• To provide an integrated regulation of the smooth muscle
and skeletal muscle sphincters of the urethra

21

What prevents retrograde ejaculation in men?

• Prostatic urethra

22

Give the nerve roots which control urine storage

• L1 & L2

23

Give the nerve roots which control bladder voiding

S2-S4

24

What are the two phases of the bladder?

• Emptying
• Filling

25

What occurs in the filling phase?

• The bladder relaxes and accommodates increasing volumes of urine
• The urethral sphincters increase their tone to maintain continence

26

What volume of urine is usually required to cause the urge to urinate?

• >150ml

27

What is the overall capacity of the urinary bladder?

• 350 - 750ml

28

Outline the nervous pathway which is activated once bladder has a volume of >400ml and urge to urinate arises

• Brain micturition centres -> Spinal micturition centres -> parasympathetic neurones -> Pelvic nerve -> Contraction of detrusor muscle -> Rise in intravesicular pressure

29

What occurs once there is a rise in intravesicular pressure in the bladder?

• Cerebral context makes a concious, executive decision to urinate by reducing sympathetic stimulation to the external urethral sphincter

30

What causes feeling of pain/temperature in bladder as it reaches 400ml filling?

• Afferent nerves from the bladder wall start to signal the need to void by producing pain/temperature