Essentials of Pathophysiology 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)

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 urine produced in kidneys ureters bladder fills Begins when bladder contains 150-250 mL of urine urine produced in kidneys ureters bladder fills with urine

Stretch Receptors in the Bladder micturition center in stretch bladder fills stretch spinal reflex pons receptors with urine receptors stimulated 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 Parasympathetic- contracts detrusor and inhibits sphincter Sympathetic- inhibits detrusor and contracts sphincter Author: Please add title.

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 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

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

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

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.

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 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.

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