Bladder and Micturition

Question 1

Describe the flow of urine from the kdiney to the urethral meatus in men & women

Answer 1

Men

• Kidney => ureter => bladder => prostate => urethra => exterior

Women

• Kidney => ureter => bladder => urethra => exterior

Question 2

What are the 3 layers of the bladder?

Answer 2

• Peritoneal Coat
• Detrusor smooth muscle
• Transitional cell lining (inner membrane)

Question 3

In females, from an anatomy standpoint what controls bladder continence?

Answer 3

• Intrinsic Sphincter
  
  • Comprised of bladder neck muscle fibers & the mid-urethral complex

Question 4

In Men, from an anatomy point of view what is responsible for bladder continence?

Answer 4

• Instrinsic sphincter
  
  • Comprised of bladder neck circular muscle fibers
  • Smooth muscle of the prostate
  • Smooth muscle of the membranous urethra

Question 5

What part of the nervous system controls micturation?

Autonomic or Central nervous system?

Name specific innervations.

Answer 5

• Control of micturation is complex and involves both autonomic and central nervous system
  
  • Parasympathetic nerve fibers - pelvic n.
    
    • Innervates the detrusor muscle (*most important innervation)
  • Sympathetic activation - hypogastric n.
    
    • Inhibits detrusor contraction
  • Motor (somatic) innervation - S2,3,4 keeps the penis off the floor - pudendal n.
    
    • Bladder, pelvic floor, urethral sphincter

Question 6

What would injury to the frontal cortex cause?

Answer 6

The cortex is predominantly inhibitory

• Leads to incontinence
• Diseases such as Dementia, stroke, & parkinsonism can cause this

Question 7

What role do the cerebellum and the brainstem play in micturition?

Answer 7

• They are facilitatory

Question 8

What are the clinical symptoms associated with issues of urine storage/Overactive Bladder (OAB)?

Answer 8

• Frequency
• Urgency
• Urge incontinence

Question 9

How is afferent activity generated in the bladder?

Answer 9

• By filling of the bladder

Question 10

What is the efferent response to bladder filling?

Answer 10

• Inhbition of detrusor activity
  
  • This is because you want to be able to continue to store urine until you are ready to excrete

Question 11

What are the clinical symptoms associated with an issue voiding - obstructive symptoms (and not storage)

Answer 11

• Hesitancy
• Weak stream
• Incomplete bladder emptying

Question 12

What are the steps and order of the micturition cycle?

They made a specific emphasis on making sure you have the order correct, otherwise it can result in dysfunction.

Answer 12

1. Increase in wall tension of the bladder
2. Afferent input overcomes the pontine micturition center threshold and provides cortical egress micturition begins
3. Pudendal n. activity ceases, the external sphincter/pelvic floor relaxes, detrusor neurons are freed and discharge
4. Proximal urethra opens
5. Bladder immediatley contracts