Essentials of Pathophysiology

CHAPTER 27

DISORDERS OF THE BLADDER

AND LOWER URINARY TRACT

CHAPTER 27

DISORDERS OF THE BLADDER

AND LOWER URINARY TRACT

PRE LECTURE QUIZ TRUE/FALSE

The storage and emptying of urine involves voluntary (somatic nervous system) control only.

Stress incontinence is the involuntary loss of urine during coughing, laughing, sneezing, or lifting, which increase intra-abdominal pressure.

The average bladder capacity (in ounces) is equal to the age (in years) + 2 of the child.

Urinary incontinence is not a common problem in elderly persons.

Flaccid bladder dysfunction is a neurogenic disorder of the bladder in which bladder emptying is impaired.

In flaccid (hypotonic) neurogenic bladder, volume is large, pressure is low, and contractions are absent. It may result from peripheral nerve damage or spinal cord damage at the S2 to S4 level (Overflow incontinence)

F

T

T

F

T

PRE LECTURE QUIZ A neurogenic disorder of bladder function,

which is manifested as a failure to store urine, is known as __________ bladder dysfunction.

The most common sign of bladder cancer is painless __________.

__________ incontinence is characterized by the involuntary loss of urine that results from overfilling of the bladder.

The _______________ nervous system promotes bladder emptying.

In men, the most important cause of urinary obstruction is external compression of the urethra caused by enlargement of the __________ gland.

hematuria

Overflow

parasympathetic

prostate

spastic

MICTURITION REFLEX

Begins when bladder contains 150-250 mL of urine

ureters

urine produced in

kidneys

bladder fills with urine

STRETCH RECEPTORS IN THE BLADDER

stretch receptors

stretch receptors

bladder fills with urine

micturition center in pons

stimulated

spinal reflex stimulated

URINATION

Detrusor muscle of bladder contracts to push urine out

Abdominal muscles may also be used

Internal sphincter relaxes

External sphincter relaxes Unconscious in young

children Under conscious control in

adults

QUESTION

Tell whether the following statement is true or false:

Abdominal muscles are used during forced urination.

Controlling Nerves

Sympathetic- inhibits

detrusor and contracts sphincter

Parasympathetic- contracts

detrusor and inhibits

sphincter

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.

PARASYMPATHETIC NERVES

M3 receptors

stretch receptors

M3 receptors

bladder fills with urine

detrusor muscle

contracts

internal sphincter relaxes and is pulled

open

parasympathetic neurons

spinal reflex stimulated

MICTURITION CENTER ALLOWS CONSCIOUS CONTROL

stretch receptors

bladder fills with urine

detrusor muscle

contracts

internal sphincter relaxes and is pulled

open

micturition center in

pons stimulated

external sphincter

relaxes

Conscious Control

QUESTION

All but which of the following stimulates urination?

a. Parasympathetic nervous system neurons

b. Micturition centerc. Sympathetic nervous systemd. Spinal reflex

ANSWER

c. Sympathetic nervous systemThe 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.

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?

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

QUESTION

Tell whether the following statement is true or false.

Benign prostatic hyperplasia (BPH) has no effect on the elimination of urine.

ANSWER

FalseBecause 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.

SCENARIO

Six months later, the husband develops urgency and incontinence.

The doctor explains that it's due to his muscle strength.

Question Which muscles is the doctor talking

about? How did they cause incontinence?

BLADDER WALL HYPERTROPHY

The bladder may also pouch outward in diverticuli