The Urinary System: Urinary Anatomy

Page 1: Introduction

  • Urinary System Overview

  • Focus on Anatomy and Physiology 2

  • Date: March 17, 2025

Page 2: Urinary System Overview

  • Anterior View of the Urinary System includes:

    • Kidney

    • Ureter

    • Urinary Bladder

    • Urethra

  • Posterior View to show different orientation and structure.

Page 3: Functions of the Kidneys

  • Primary functions include:

    • Filter blood plasma and eliminate waste products.

    • Regulate:

      • Blood volume

      • Blood pressure

      • Osmolarity

    • Secrete erythropoietin to stimulate red blood cell production.

    • Contribute to homeostasis in:

      • Electrolyte balance

      • Acid-base balance

      • Calcium levels.

Page 4: External Structure of Kidneys

  • Protective Connective Tissue Coverings:

    • Renal fascia: binds kidneys to posterior body wall.

    • Perirenal fat capsule: cushions kidneys and holds in place.

    • Fibrous capsule: encloses kidneys protecting from trauma and infection.

Page 5: Internal Structure of Kidneys

  • Renal Parenchyma:

    • Tissue that forms urine.

  • Renal Sinus:

    • Contains blood and lymphatic vessels, nerves, and urine-collecting structures.

Page 6: Internal Structure Details

  • Renal Cortex:

    • Outer layer projecting renal columns into renal sinus.

  • Renal Medulla:

    • Inner layer divided into renal pyramids by renal columns.

    • Papilla: tip of each pyramid.

    • Lobe: comprises one pyramid plus overlying cortex.

Page 7: Renal Circulation

  • Major components include:

    • Arcuate arteries

    • Cortical radiate arteries

    • Interlobar artery

    • Renal artery

    • Segmental arteries

Page 8: Detailed Renal Circulation

  • Key elements in circulation:

    • Cortical radiate artery

    • Glomerulus: capillary network for filtration.

    • Afferent arterioles and efferent arterioles for blood flow regulation.

Page 9: Capillary Network

  • Peritubular Capillaries:

    • Surround nephron for reabsorption and secretion.

  • Cortical radiate vein: drains blood away from the capillaries.

  • Efferent arteriole continues circulation.

  • Arcuate vein and Vasa recta mentioned for renal vasculature.

Page 10: Venous Structures

  • Interlobar veins, Arcuate veins, and Cortical radiate veins: responsible for draining blood from kidneys into the renal vein.

Page 11: Systematic Overview of Vessels

  • Overall renal blood flow involves:

    • Aorta

    • Renal artery and its branches

    • Inferior vena cava and renal vein for return of purified blood.

  • Detailing the pathway of blood through various arteries and veins associated with nephron function.

Page 12: Nephrons

  • Functional Units of kidneys:

    • Approximately 1 million nephrons per kidney.

    • Renal Corpuscle: responsible for blood plasma filtration.

    • Renal Tubule: converts filtrate into urine.

Page 13: Renal Corpuscle Breakdown

  • Consists of:

    • Glomerulus and the glomerular capsule (parietal and visceral layers).

  • Capsular space collects filtrate.

  • Vascular Pole: entry and exit points for afferent and efferent arterioles.

  • Urinary Pole transitions to renal tubule.

Page 14: Renal Tubule Structure

  • Proximal Convoluted Tubule (PCT):

    • Longest and most coiled section with prominent microvilli aiding absorption.

  • Nephron Loop:

    • Comprised of descending and ascending limbs.

Page 15: Continuing Renal Tubule

  • Distal Convoluted Tubule (DCT):

    • Shorter and less coiled than PCT, lacks microvilli.

  • Collecting Duct:

    • Receives fluid from several nephrons and transports it down to the medulla, forming papillary ducts.

Page 16: Papillary Ducts

  • Ducts end at the pores of each papilla where urine drains into the ureter.

Page 17: Nephron Subtypes

  • Cortical Nephrons:

    • 85% of nephrons, short nephron loops, associate with peritubular capillaries.

  • Juxtamedullary Nephrons:

    • 15%, long nephron loops, associate with the vasa recta, crucial for urine concentration.

Page 18: Ureters

  • Continuation of renal pelvis, opening into bladder floor.

  • Contains one-way valves to prevent backflow of urine.

Page 19: Bladder Structure

  • Detrusor Muscle: three layers of smooth muscle that contract to expel urine.

  • Mucosa: thick epithelial layer with rugae that allows for expansion.

  • Internal Urethral Sphincter for involuntary urination control.

Page 20: Urethra: Females

  • Extends from bladder to external urethral orifice.

  • External Urethral Sphincter: permits voluntary control during urination.

Page 21: Urethra: Males

  • Sections detailed:

    • Prostatic: through prostate.

    • Membranous: through pelvic floor.

    • Spongy (Penile): extending to external urethral orifice.

Page 22: Urinary Tract Infection (UTI)

  • Cause: E. coli from digestive tract (80% of UTIs).

  • More prevalent in females.

  • Symptoms include:

    • Frequent and painful urination

    • Low back pain

  • Treatment considerations:

    • Risk of chronic pyelonephritis affecting renal function.

    • Cranberry juice suggested to prevent E. coli adhesion.

Page 23: Conclusion

  • Review of urinary system anatomy and function concluded.