Urinary System Flashcards
(20 cards)
Overview of the Urinary System
Function: Filters blood to remove waste, balances fluids, electrolytes, and pH, regulates blood pressure.
Main Organs: Kidneys, ureters, bladder, and urethra.
Urine Formation: Filtration, reabsorption, secretion
Anatomy of the Kidney
Regions:
Cortex: Outer region.
Medulla: Inner region with renal pyramids.
Pelvis: Funnel-shaped structure collecting urine.
Nephron: Functional unit responsible for filtering blood and forming urine.
The Nephron
Components:
Glomerulus: Filters blood.
Bowman’s Capsule: Surrounds the glomerulus, collects filtrate.
Proximal Convoluted Tubule: Reabsorbs nutrients, water, and ions.
Loop of Henle: Concentrates urine by reabsorbing water.
Distal Convoluted Tubule: Further regulation of ions and pH.
Collecting Duct: Final concentration of urine.
Glomerular Filtration
Definition: The first step in urine formation where blood is filtered in the glomerulus.
Filtration Rate (GFR): The amount of blood filtered per minute (~125 mL/min).
Filtrate: Contains water, electrolytes, glucose, urea, and small molecules.
Reabsorption in the Nephron
Location: Mainly in the proximal convoluted tubule.
Reabsorbed Substances: Water, glucose, amino acids, sodium, potassium, bicarbonate.
Purpose: Retains essential nutrients and fluids in the blood.
Secretion in the Nephron
Definition: The active transport of waste and excess substances from the blood into the nephron.
Examples: Hydrogen ions (H+), potassium (K+), ammonia (NH3), certain drugs.
Location: Mostly in the distal convoluted tubule and collecting duct.
Role of the Loop of Henle
Function: Concentrates urine by reabsorbing water and sodium chloride.
Descending Limb: Permeable to water, reabsorbs water into the blood.
Ascending Limb: Impermeable to water, reabsorbs sodium and chloride.
Antidiuretic Hormone (ADH)
Source: Released from the posterior pituitary.
Function: Increases water reabsorption in the collecting ducts to concentrate urine.
Effect: Reduces urine output, helps maintain blood pressure and hydration.
Aldosterone
Source: Produced by the adrenal cortex.
Function: Increases sodium reabsorption in the distal tubule and collecting duct, leading to water retention.
Effect: Increases blood pressure and blood volume.
Renin-Angiotensin-Aldosterone System (RAAS)
Activation Trigger: Low blood pressure or low sodium levels.
Renin: Released by the kidneys, converts angiotensinogen to angiotensin I.
Angiotensin II: Causes vasoconstriction, stimulates aldosterone release.
Result: Increases blood pressure and sodium retention.
Urinary Bladder
Function: Stores urine until micturition (urination).
Capacity: ~400-600 mL.
Detrusor Muscle: Contracts to expel urine during urination.
Internal and External Sphincters: Control urine release.
Urethra
Function: Drains urine from the bladder out of the body.
Length:
Male: ~20 cm.
Female: ~4 cm.
Infection Risk: Shorter female urethra increases the risk of urinary tract infections (UTIs).
Urine Composition
Normal Components: Water, urea, creatinine, electrolytes (sodium, potassium), and waste products.
Abnormal Components (Indicating Disease): Protein (proteinuria), glucose (glycosuria), blood (hematuria), bacteria (bacteriuria).
Urinary Tract Infection (UTI)
Causes: Bacterial infection (often E. coli) in the urethra, bladder, or kidneys.
Symptoms: Dysuria (painful urination), frequency, urgency, cloudy or foul-smelling urine.
Treatment: Antibiotics, increased fluid intake.
Acute Kidney Injury (AKI)
Definition: Sudden decrease in kidney function, leading to an accumulation of waste products.
Causes: Hypotension, sepsis, nephrotoxic drugs.
Symptoms: Oliguria (low urine output), fluid retention, elevated creatinine.
Treatment: Treat underlying cause, dialysis in severe cases.
Chronic Kidney Disease (CKD)
Definition: Gradual loss of kidney function over time.
Causes: Diabetes, hypertension, glomerulonephritis.
Stages: 5 stages based on glomerular filtration rate (GFR), with stage 5 being end-stage renal disease (ESRD).
Treatment: Lifestyle changes, medications, dialysis, kidney transplant.
Hemodialysis
Definition: A procedure to filter waste and excess fluids from the blood when kidneys are no longer functioning properly.
Process: Blood is pumped through a dialyzer, which removes waste and returns clean blood to the body.
Frequency: Usually 3 times per week for several hours.
Peritoneal Dialysis
Definition: Uses the lining of the abdominal cavity (peritoneum) to filter waste from the blood.
Process: Dialysis fluid is introduced into the abdomen, where it absorbs waste, then is drained out.
Advantages: Can be done at home, allows for more flexibility.
Fluid and Electrolyte Balance
Kidney Role: Regulates levels of sodium, potassium, and other electrolytes.
Imbalances:
Hyponatremia: Low sodium, often due to overhydration.
Hyperkalemia: High potassium, often due to kidney failure.
Hypokalemia: Low potassium, often due to diuretics or vomiting.
Nursing Assessment of the Urinary System
History: Inquire about urinary frequency, dysuria, hematuria, nocturia, and incontinence.
Physical Exam: Palpate the abdomen for bladder distention, flank pain, assess fluid status.
Diagnostic Tests:
Urinalysis.
Blood tests (BUN, creatinine).
Imaging (ultrasound, CT scan).
