Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 26 Disorders of Urine Elimination

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Micturition Reflex Begins when bladder contains mL of urine ureters urine produced in kidneys bladder fills with urine

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Stretch Receptors in the Bladder stretch receptors stretch receptors bladder fills with urine micturition center in pons stimulated spinal reflex stimulated

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Urination Detrusor muscle of bladder contracts to push urine out Abdominal muscles may also be used Internal sphincter relaxes External sphincter relaxes

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false: Abdominal muscles are used during forced urination.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 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.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question All but which of the following stimulates urination? a.Parasympathetic nervous system neurons b.Micturition center c.Sympathetic nervous system d.Spinal reflex

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer c.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.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 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?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false. Benign prostatic hyperplasia (BPH) has no effect on the elimination of urine.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 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.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 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?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Bladder Wall Hypertrophy The bladder may also pouch outward in diverticuli