Ch 38: Urinary System Overview

Ch 38: Urinary System Overview

Structure and Function of the Urinary System

The urinary system is essential for maintaining the body's fluid and electrolyte balance, removing waste products, and regulating blood volume. It consists of the kidneys, ureters, bladder, and urethra.

• Kidneys and Ureters: The kidneys filter blood, excreting waste as urine while retaining necessary substances. Ureters transport urine from the kidneys to the bladder.

• Bladder: A smooth muscle sac (detrusor muscle) that temporarily stores urine. It is composed of three muscle layers: inner longitudinal, middle circular, and outer longitudinal.

• Urethra: Conveys urine from the bladder to the exterior. In males, it also serves a reproductive function; in females, it is solely excretory and is not external to the body.

Example: The nephrons in the kidneys regulate fluid balance through selective reabsorption and secretion, ensuring homeostasis.

Physiology of Urination (Micturition)

The Act of Urination

Micturition is the process of emptying the bladder, involving both involuntary and voluntary muscle actions.

• Detrusor muscle contracts and the internal sphincter relaxes, allowing urine to enter the posterior urethra.

• Perineal muscles and external sphincter relax, and the abdominal wall contracts slightly.

• Diaphragm lowers, facilitating the flow of urine out of the body.

Key Term: Micturition is another term for urination or voiding.

Factors Affecting Urinary Elimination

Developmental, Lifestyle, and Health Factors

Several factors influence urinary elimination patterns and health.

• Developmental Considerations: Children typically achieve toilet training between ages 2-3. Aging can lead to nocturia, increased frequency, retention, and reduced voluntary control.

• Food and Fluid Intake: Hydration status and dietary choices affect urine volume and composition.

• Psychological Variables: Stress and privacy concerns can impact voiding habits.

• Activity and Muscle Tone: Physical activity and muscle strength support normal elimination.

• Pathologic Conditions: Diseases such as diabetes, hypertension, and urinary tract infections (UTIs) can impair urinary function.

• Medications: Certain drugs alter urine production and characteristics (see table below).

Table: Effects of Medications on Urine Color

Medication	Urine Color
Anticoagulants	Red
Diuretics	Pale yellow
Pyridium	Orange to orange-red
Amitriptyline/B-complex vitamins	Green or blue-green
Levodopa	Brown or black

Common Urinary Problems and Diseases

Diseases Associated with Renal Dysfunction

• Congenital urinary tract abnormalities

• Polycystic kidney disease

• Urinary tract infection (UTI)

• Urinary calculi (stones)

• Hypertension

• Diabetes mellitus

• Gout

• Connective tissue disorders

Example: Diabetes mellitus can cause kidney damage over time, leading to chronic kidney disease.

Types of Urinary Incontinence

• Transient: Sudden onset, lasts less than 6 months.

• Mixed: Combination of two or more types.

• Overflow: Bladder overdistention and overflow.

• Functional: Caused by factors outside the urinary tract (e.g., mobility issues).

• Reflex: Bladder empties without sensation of need to void.

• Total: Continuous, unpredictable loss of urine.

• Stress: Involuntary loss due to increased intra-abdominal pressure (e.g., coughing, sneezing).

Assessment of Urinary Function

Nursing History and Physical Assessment

• History: Usual elimination patterns, recent changes, aids to elimination, voiding difficulties, urinary diversions.

• Physical Assessment: Palpation of kidneys (by advanced practitioners), bladder palpation/percussion, inspection of urethral orifice, skin assessment, and urine characteristics (color, odor, clarity, sediment).

Urine Collection and Measurement

• Measure output using a calibrated container at eye level.

• Specimen types: routine urinalysis, clean-catch/midstream, sterile, 24-hour collection, and specimens from urinary diversions.

• For indwelling catheters, collect specimens directly from the catheter, not the collection receptacle.

Promoting Healthy Urinary Elimination

Interventions and Patient Goals

• Maintain regular voiding habits and fluid intake.

• Strengthen pelvic floor muscles to support continence.

• Assist with toileting as needed.

• Monitor for and address incontinence, retention, and infection risks.

• Patient goals: balanced intake/output, complete bladder emptying, ease of voiding, skin integrity, and self-care behaviors.

Patients at Risk for UTIs

• Sexually active individuals with female genitalia

• Diaphragm users for contraception

• Postmenopausal individuals

• Patients with indwelling catheters

• People with diabetes mellitus

• Older adults

Urinary Devices and Catheterization

External and Internal Devices

• External devices: Urinary sheaths and collection systems for non-invasive management.

• Catheterization: Used for acute retention, sterile specimen collection, accurate output measurement, wound healing, pre/post-surgical management, comfort in end-of-life care, and prolonged immobilization.

• Types of catheters: Intermittent urethral, indwelling urethral, and suprapubic catheters.

Nursing Interventions

• Insertion and care of urethral catheters

• Care for patients with urologic stents or urinary diversions

• Support for patients receiving dialysis

Absorbent Products

• Consider patient’s functional ability, incontinence type/severity, gender, caregiver availability, previous treatment outcomes, and patient preference when selecting products.

Key Terms and Definitions

• Anuria: Less than 50 mL urine output in 24 hours; indicates kidney failure.

• Dysuria: Painful or difficult urination.

• Glycosuria: Presence of glucose in urine.

• Pyuria: Presence of pus in urine.

• Nocturia: Nighttime urination.

• Enuresis: Involuntary urination, especially in children.

Sample Questions and Answers

• Q: Which term describes a condition in which 24-hour urine output is less than 50 mL? A: Anuria

• Q: Diuretics cause increased urine production, resulting in the need for increased urination and possibly urge incontinence. (True/False) A: True

• Q: Normal fresh urine has an ammonia odor. (True/False) A: False. Fresh urine is aromatic; ammonia odor develops as urine stands.

• Q: A urine specimen from a patient with an indwelling catheter should be obtained from the collection receptacle. (True/False) A: False. It should be obtained from the catheter itself.

• Q: There are no interventions effective for preventing urinary incontinence. (True/False) A: False. There are effective interventions.

Additional info: This summary expands on the original notes with definitions, examples, and context to support understanding for Personal Health students.