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

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

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

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Controlling Nerves Author: Please add title.

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

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.

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 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 center 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. SNS (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 hypertrophy (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 is 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