Urinary

Urinary System: Overview

  • Learning Objectives:

    • Apply medical language rules related to the urinary system.

    • Identify key word components and terms related to the urinary system.

    • Categorize diagnostic, therapeutic, procedural, or anatomic terms linked to the system.

    • Use terminology associated with diseases and disorders of the urinary system.

Introduction to the Urinary System

  • Primary Functions:

    • Cleanses blood and removes wastes from the body.

    • Regulates body pH, blood pressure, and blood solute concentration.

    • Produces erythropoietin (EPO) for red blood cell production (85% produced in kidneys).

    • Synthesizes active form of vitamin D (calcitriol).

  • Impact of Kidney Failure:

    • Loss of these functions leads to severe homeostasis disruptions.

Anatomy of the Urinary System

Kidneys

  • Size and Location:

    • Size of a fist; located retroperitoneally along the spine, between the parietal peritoneum and posterior abdominal wall.

    • The right kidney is smaller and lower than the left due to the liver's position.

  • Vascularization:

    • Receives about 25% of cardiac output.

Internal Structure of the Kidneys

  • Regions:

    • Renal Cortex: Outer region.

    • Renal Medulla: Inner region featuring renal pyramids and renal papillae.

  • Renal Columns:

    • Extensions of connective tissue separating renal pyramids.

    • Support framework for vessels in the kidney.

  • Renal Hilum:

    • Entry and exit site for vessels and nerves.

    • Formation of renal pelvis from the merging of calyxes.

Nephrons

  • Functional Unit:

    • Approximately 1.3 million nephrons per kidney.

    • Responsible for filtering blood and balancing constituents.

  • Components:

    • Glomerulus: Capillary tuft for filtration.

    • Bowman's Capsule: Encloses glomerulus.

    • Efferent arterioles direct flow from the glomerulus.

  • Portal System:

    • Unique structure where arterioles exist between capillary beds.

Ureters and Bladder

  • Ureters:

    • Propulsion of urine via peristalsis (30 cm long).

  • Bladder:

    • Transports urine from ureters; anatomical differences exist between genders.

  • Urethra:

    • Conveys urine from the bladder to the outside; regulated by internal and external urinary sphincters.

Micturition Reflex

  • Definition:

    • The process of urination occurring through autonomic and voluntary mechanisms.

    • Urgency sensed at around 150 ml bladder capacity.

  • Normal Physiology:

    • Bladder stretch receptors transmit impulses leading to detrusor muscle contractions.

Physiological Functions of the Urinary System

  • Waste Removal: Excretes metabolic wastes and medications.

  • Fluid and Electrolyte Balance: Regulates body fluids and electrolytes.

  • Hormonal Release: Controls blood pressure and red blood cell production (EPO).

  • Bone Health: Helps manage calcium and phosphorus levels.

Nephron Processes

Glomerular Filtration Rate (GFR)

  • Definition:

    • Volume of filtrate produced by kidneys per minute, approx. 125 mL/min (men) and 105 mL/min (women).

  • Regulation:

    • Influenced by hydrostatic and osmotic pressures.

Reabsorption and Secretion

  • Filtration Modification:

    • Most solutes absorbed back into circulation; excess toxic components secreted.

  • Urinalysis Utility:

    • Can reveal kidney dysfunction, electrolyte imbalances, or infections.

Urinary Disorders

  • Glomerulonephritis: Inflammation leading to protein/blood in urine.

  • Hydronephrosis: Kidney swelling due to urine retention.

  • Polycystic Kidney Disease: Cyst formation affecting kidney function.

  • Renal Cell Cancer: Common cancer in kidneys, often requiring surgical intervention.

  • Urinary Tract Infection: Infection caused by pathogens; diagnosed via culture.

  • Urinary Incontinence: Loss of bladder control due to weak muscles.

Medical Terminology and Procedures

Urology and Urologists

  • Urology: Specialty focusing on urinary and male reproductive system disorders.

  • Common Procedures:

    • Urinalysis: Testing urine for metabolic products.

    • Cystoscopy: Visual examination of bladder.

    • Dialysis: Waste removal treatment for renal failure.

    • Kidney Transplant: Surgical procedure to replace failing kidneys.

Conclusion

  • Understanding the anatomy, physiology, and common disorders of the urinary system is essential for diagnosing and managing urinary health.


Parts of the Kidney and Their Purposes

  1. Renal Cortex

    • Purpose: The outer region of the kidney that contains the glomeruli and convoluted tubules, playing a role in filtering blood and forming urine.

  2. Renal Medulla

    • Purpose: The inner region featuring renal pyramids and renal papillae, involved in the concentration of urine and the reabsorption of water and solutes.

  3. Renal Pyramids

    • Purpose: Structures within the renal medulla that contain nephrons; they funnel urine into the renal papillae.

  4. Renal Papillae

    • Purpose: The tips of the renal pyramids where urine drips into the minor calyx.

  5. Renal Columns

    • Purpose: Extensions of cortical tissue between the renal pyramids that support the kidney's structure and contain blood vessels.

  6. Renal Hilum

    • Purpose: The entry and exit point for blood vessels and nerves; also where the renal pelvis forms from the merging of calyxes.

  7. Nephrons

    • Purpose: The functional units of the kidney (about 1.3 million per kidney) responsible for filtering blood, excreting waste, and balancing fluid and electrolyte levels.

    • Key Components of Nephrons:

      • Glomerulus: A tuft of capillaries for filtration.

      • Bowman's Capsule: Encloses the glomerulus and collects filtrate.

      • Efferent Arterioles: Directs blood flow from the glomerulus.

  8. Renal Pelvis

    • Purpose: The funnel-shaped area at the center of the kidney that collects urine from the calyces and channels it into the ureter.

  9. Calyces

    • Purpose: Structures that collect urine from the renal pyramids and direct it to the renal pelvis.