Elimination is a fundamental physiological function necessary for maintaining homeostasis in the body. It includes the processes of urinary and bowel elimination. Nursing care focuses on ensuring normal elimination patterns, preventing complications, and assisting patients who have elimination problems.
1. Urinary Elimination
Urinary elimination is essential for removing metabolic waste, maintaining fluid and electrolyte balance, and regulating blood pressure.
Normal Urinary Elimination Process
The kidneys filter waste and excess fluids from the blood.
The urine is transported via the ureters to the bladder.
The bladder stores urine until voiding occurs.
The urethra allows urine to exit the body.
Factors Affecting Urinary Elimination
Age – Infants and older adults have different elimination patterns.
Diet and Fluid Intake – Dehydration leads to concentrated urine, while excessive fluid intake increases urination.
Medications – Diuretics increase urination, while opioids may cause retention.
Psychological Factors – Stress and privacy issues may affect elimination.
Neurological Conditions – Damage to the nervous system can impair bladder control.
Common Urinary Elimination Problems
Urinary Retention – Inability to empty the bladder completely.
Urinary Incontinence – Loss of bladder control (stress, urge, overflow, functional).
Urinary Tract Infections (UTI) – Bacterial infection in the urinary tract.
Renal Failure – Inability of the kidneys to filter waste.
Nursing Interventions for Urinary Elimination
Assessment – Monitor urine output, color, odor, and consistency.
Bladder Training – Encourage scheduled voiding to prevent incontinence.
Catheterization – Used when patients cannot void voluntarily.
Encouraging Fluid Intake – Prevents dehydration and promotes urinary health.
Hygiene Measures – Prevents infections, especially in catheterized patients.
Medication Administration – Prescribed diuretics, antibiotics for UTIs.
2. Bowel Elimination
Bowel elimination is the process of expelling solid waste from the digestive system.
Normal Bowel Elimination Process
Digestion begins in the stomach.
Nutrients are absorbed in the small intestine.
Water is absorbed in the large intestine, and waste forms stool.
The rectum stores feces until defecation occurs.
Factors Affecting Bowel Elimination
Dietary Habits – High fiber intake promotes healthy bowel movements.
Toileting Schedule – Establish a routine for defecation.
Administering Laxatives or Stool Softeners – As prescribed for constipation.
Managing Diarrhea – Administer anti-diarrheal medications and encourage rehydration.
Digital Removal of Stool – For fecal impaction when necessary.
3. Special Considerations for Bedridden Patients
Use of Bedpans and Urinals – For patients unable to move to the toilet.
Perineal Care – Prevents skin breakdown and infections.
Preventing Skin Breakdown – Regular position changes and hygiene for incontinent patients.
Monitoring Input and Output (I&O) – Essential for maintaining fluid balance.
Urinary Elimination: Review of Physiology of Urine Elimination.
Urinary elimination is a vital physiological process that maintains fluid and electrolyte balance, removes waste products, and helps regulate blood pressure. The urinary system consists of the kidneys, ureters, bladder, and urethra, which work together to form and excrete urine.
1. Anatomy of the Urinary System
The urinary system includes:
Kidneys – Filter blood and produce urine.
Ureters – Transport urine from the kidneys to the bladder.
Bladder – Stores urine until excretion.
Urethra – Expels urine from the body.
2. Physiology of Urine Formation
The process of urine formation occurs in the nephrons of the kidneys and involves three main stages:
A. Glomerular Filtration
Occurs in the renal corpuscle (glomerulus and Bowman’s capsule).
Blood is filtered through the glomerular capillaries.
Water, electrolytes, glucose, urea, and small solutes pass into the renal tubule.
Large proteins and blood cells remain in the bloodstream.
B. Tubular Reabsorption
Takes place in the proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
Essential substances like glucose, amino acids, and water are reabsorbed into the bloodstream.
Prevents excessive loss of fluids and nutrients.
C. Tubular Secretion
Occurs mainly in the distal convoluted tubule and collecting ducts.
Waste products like hydrogen ions (H⁺), potassium (K⁺), and drugs are secreted into the filtrate.
Helps maintain acid-base balance.
3. Physiology of Urine Storage and Excretion
A. Urine Storage (Bladder Function)
The urinary bladder is a muscular organ that expands as it fills with urine.
The bladder can store 400-600 mL of urine before the urge to urinate occurs.
The internal urethral sphincter (involuntary) and external urethral sphincter (voluntary) control urine flow.
B. Micturition Reflex (Urination)
Bladder Filling: Stretch receptors in the bladder send signals to the brain.
Signal to the Brain: The brain processes the urge to void.
Sphincter Control:
The internal urethral sphincter relaxes (involuntary).
The external urethral sphincter is consciously controlled.
Urine Expulsion: The detrusor muscle contracts, forcing urine out through the urethra.
4. Factors Affecting Urinary Elimination
Age – Infants and elderly individuals have different bladder capacities and control.
Hydration – Fluid intake affects urine volume and concentration.
Medications – Diuretics increase urination, while anticholinergics reduce it.
Lifestyle and Diet – Caffeine and alcohol act as diuretics.
Infections and Diseases – Urinary tract infections (UTIs) and kidney disease impair elimination.
5. Nursing Considerations in Urinary Elimination
Monitor Urine Output: Normal output is 800–2000 mL per day.
Assess Urine Characteristics: Color, clarity, odor, and consistency.
Encourage Proper Hydration: Prevents concentrated urine and UTIs.
Bladder Training: Helps patients with incontinence.
Catheterization: Used for urinary retention.
Prevent Infection: Maintain hygiene and promote perineal care.
Composition and Characteristics of Urine
Urine is a liquid by-product of metabolism that is excreted by the kidneys. It primarily consists of water, waste products, and various solutes. The composition and characteristics of urine provide essential information about the body’s metabolic and physiological status.
1. Composition of Urine
Urine is composed of 95% water and 5% dissolved solids and gases. The main components include:
A. Water (95%)
Acts as a solvent to dissolve various waste products.
Helps in the elimination of excess fluids and toxins.
B. Organic Substances (Waste Products)
Urea (2%) – A by-product of protein metabolism.
Creatinine – A waste product from muscle metabolism.
Uric Acid – Formed from the breakdown of nucleic acids.
Ammonia – Derived from amino acid metabolism.
C. Inorganic Substances (Electrolytes)
Sodium (Na⁺) – Helps in fluid balance.
Potassium (K⁺) – Essential for nerve and muscle function.
Chloride (Cl⁻) – Maintains electrolyte balance.
Calcium (Ca²⁺) – Involved in bone metabolism.
Magnesium (Mg²⁺) – Regulates enzymatic reactions.
Phosphate (PO₄³⁻) – Maintains acid-base balance.
Bicarbonate (HCO₃⁻) – Helps regulate pH levels.
D. Other Components
Hormones – Small traces of hormones like ADH (antidiuretic hormone).
Pigments – Urochrome gives urine its yellow color.
Enzymes – May include trace amounts of specific enzymes.
2. Characteristics of Normal Urine
Urine has several physical and chemical properties that help in assessing kidney function and overall health.
A. Physical Characteristics
Characteristic
Normal Value
Color
Pale yellow to deep amber (due to urochrome pigment)
Clarity
Clear to slightly cloudy
Odor
Mild aromatic smell; ammonia-like when standing
pH
4.5 – 8 (average ~6)
Specific Gravity
1.005 – 1.030 (measures urine concentration)
Volume
800 – 2000 mL per day (varies with fluid intake)
B. Abnormal Urine Characteristics
Abnormality
Possible Causes
Dark Yellow / Brown
Dehydration, liver disease (bilirubin in urine)
Red / Pink
Hematuria (blood in urine), kidney stones, infection
Cloudy
Infection, pus, proteinuria
Sweet Odor
Diabetes mellitus (presence of glucose or ketones)
High Specific Gravity (>1.030)
Dehydration, concentrated urine
Low Specific Gravity (<1.005)
Overhydration, kidney disease
Acidic Urine (pH < 4.5)
Starvation, high protein diet, metabolic acidosis
Alkaline Urine (pH > 8.0)
Urinary tract infection (UTI), diet rich in fruits/vegetables
3. Abnormal Constituents in Urine
The presence of unusual substances in urine may indicate disease conditions:
Urination (micturition) is a vital physiological function that helps in the excretion of waste products and maintenance of fluid balance. Various factors influence urinary elimination, including physiological, psychological, environmental, and pathological conditions. Understanding these factors is essential for nurses to provide appropriate care and prevent complications related to urinary health.
1. Physiological Factors
These factors affect the normal process of urination based on body functions and development.
A. Age
Infants and Children:
Immature kidney function leads to dilute urine.
Lack of voluntary bladder control until around 2-3 years of age.
Older Adults:
Decreased bladder capacity → More frequent urination.
Weakened bladder muscles → Urinary retention or incontinence.
Men may develop prostate enlargement → Difficulty in urination.
B. Fluid Intake
Increased fluid intake increases urine production (diuresis).
Dehydration leads to concentrated urine and lower output.
High-protein or high-sodium diets cause reduced urine output (water retention).
C. Hormonal Influence
Antidiuretic Hormone (ADH): Regulates water retention.