1. Chapter 27 Disorders of the Bladder and Lower Urinary Tract
Essentials of Pathophysiology
Chapter 27 Disorders of the Bladder and Lower Urinary Tract

2. urine produced in kidneys ureters bladder fills with urine
Micturition Reflex
produced in
Begins when bladder contains 150–250 mL of urine
kidneys
ureters
bladder fills
with urine

3. Stretch Receptors in the Bladder
micturition
center in
stretch
bladder fills
stretch
spinal reflex
pons
receptors
with urine
receptors
stimulated
stimulated

4. Urination Detrusor muscle of bladder contracts to push urine out
Abdominal muscles may also be used
Internal sphincter relaxes
External sphincter relaxes

5. Author: Please add title.

6. Controlling Nerves
Author: Please add title.

7. Question
Tell whether the following statement is true or false: Abdominal muscles are used during forced urination.

8. Answer
Sympathetic nervous system
The micturition center in the pons and the spinal reflex respond to stretch receptors in the bladder to stimulate urination. The parasympathetic nervous system neurons are stimulated by the spinal reflex to cause urination. Sympathetic NS (fight-or-flight) decreases activity in both the excretory and digestive systems.

9. Answer
True Passive urination occurs when the bladder’s detrusor muscle contracts, and both internal and external sphincter muscles are relaxed. Abdominal muscles contract in order to force the excretion of urine.

10. Parasympathetic Nerves
bladder fills
stretch
spinal reflex
with urine
receptors
stimulated
detrusor
parasympathetic
muscle
M3 receptors
neurons
contracts
M3 receptors
internal sphincter
relaxes and is pulled
open

11. Micturition Center Allows Conscious Control
center in
stretch
bladder fills
pons
receptors
with urine
stimulated
detrusor
muscle
contracts
external
internal sphincter
sphincter
relaxes and is pulled
relaxes
open

12. Question
All but which of the following stimulates urination?
Parasympathetic nervous system neurons
Micturition center
Sympathetic nervous center
Spinal reflex

13. Answer
Sympathetic nervous system
The micturition center in the pons and the spinal reflex respond to stretch receptors in the bladder to stimulate urination. The parasympathetic nervous system neurons are stimulated by the spinal reflex to cause urination.
SNS (fight-or-flight) decreases activity in both the excretory and digestive systems.

14. Scenario
A 63-year-old woman complains of stress incontinence, and her 60-year-old husband complains of difficulty voiding.
Question:
Why do people of the same age and lifestyle have opposite problems with urination?

15. Male vs. Female Urethra Female is urethra 2.5–3.5 cm long
Allows urine to pass more freely
Male urethra 16.5–18.5 cm long
Passes through prostate

16. Question
Tell whether the following statement is true or false: Benign prostatic hypertrophy (BPH) has no effect on the elimination of urine.

17. Answer
False Because the male urethra passes through the prostate gland, if the gland increases in size the urethra may become compressed or obstructed. This decreases the diameter of the urethra’s lumen, and the ability to urinate is diminished.

18. Scenario
Six months later, the husband develops urgency and incontinence…
The doctor explains that it is due to his muscle strength.
Question:
Which muscles is the doctor talking about?
How did they cause incontinence?

19. Bladder Wall Hypertrophy
The bladder may also pouch outward in diverticuli