Urinary System: Lab Practical Study Guide

The Urinary System

Overview

The urinary system is responsible for filtering blood, removing waste products, and regulating fluid and electrolyte balance. This study guide covers the key anatomical structures and histological features you must identify for lab practicals, as well as basic urinalysis procedures.

Kidney Histology

• Glomerulus: A network of capillaries involved in the filtration of blood to form urine. Located within the renal corpuscle.

• Glomerular (Bowman's) Capsule: A cup-shaped structure that surrounds the glomerulus and collects the filtrate.

• Capsular Space: The space between the glomerulus and Bowman's capsule where filtrate accumulates before entering the renal tubule.

Example: On a kidney slide, the glomerulus appears as a dense, round cluster of cells, surrounded by a clear space (capsular space) and the Bowman's capsule.

Urinary Bladder Histology

• Transitional Epithelium of Mucosa: Specialized epithelium that allows the bladder to stretch as it fills with urine.

• Detrusor Muscle: The smooth muscle layer responsible for contracting to expel urine from the bladder.

Example: Transitional epithelium appears as multiple layers of cells that can change shape, while the detrusor muscle is seen as thick bundles of smooth muscle beneath the mucosa.

Ureter Histology (Cross-Section)

• Transitional Epithelium: Lines the lumen of the ureter, providing protection and flexibility as urine passes through.

Example: In cross-section, the ureter shows a star-shaped lumen lined by transitional epithelium, surrounded by smooth muscle layers.

Urinary Structures in the Fetal Pig and Models

Fetal Pig Dissection

• Kidneys: Bean-shaped organs that filter blood and produce urine.

• Ureters: Tubes that transport urine from the kidneys to the bladder.

• Urinary Bladder: Stores urine before excretion.

• Parietal Peritoneum: The serous membrane lining the abdominal cavity.

• Renal Artery and Vein: Blood vessels supplying and draining the kidneys.

• Genital Pore (Male): Opening for the urogenital tract in males.

• Urogenital Papilla (Female): External structure marking the opening of the urogenital tract in females.

Sheep Kidney Anatomy

• Renal Capsule: The tough, fibrous outer covering of the kidney.

• Cortex: The outer region of the kidney containing glomeruli and convoluted tubules.

• Pyramids: Triangular regions in the medulla containing collecting ducts.

• Columns: Extensions of cortical tissue between the pyramids.

• Medulla: The inner region of the kidney, organized into pyramids.

• Papilla: The tip of each pyramid, where urine drains into the minor calyces.

• Minor Calyces: Small chambers that collect urine from the papillae.

• Major Calyces: Larger chambers formed by the convergence of minor calyces.

• Renal Pelvis: The central collecting region that funnels urine into the ureter.

• Ureter: The tube that carries urine from the renal pelvis to the bladder.

Urinary System Models

• Kidney, Ureter, Bladder: Main organs of the urinary system.

• Pyramids, Cortex, Columns: Internal structures of the kidney.

• Minor and Major Calyces, Pelvis: Urine-collecting structures.

• Renal Corpuscle: Consists of the glomerulus and Bowman's capsule.

• Renal Tubules: Tubular structures including the proximal convoluted tubule (PCT), nephron loop (loop of Henle), and distal convoluted tubule (DCT).

Example: On a model, trace the path of urine from the cortex (where filtration occurs) through the pyramids, into the calyces, and out via the ureter.

Urinalysis

• Labstix: Chemical test strips used to detect components in urine such as glucose, protein, ketones, blood, and pH.

• Refractometer: Instrument used to measure the specific gravity (concentration) of urine samples.

• Normal Urine Components: Water, urea, electrolytes, and small amounts of other waste products.

• Abnormal Urine Components: Presence of glucose, protein, blood, or ketones may indicate disease.

• Normal Urine Output: Typically 1-2 liters per day in a healthy adult.

Test	Normal Result	Abnormal Indication
Glucose	Negative	Diabetes Mellitus
Protein	Negative	Kidney Disease
Blood	Negative	Infection, Trauma
Specific Gravity	1.005 - 1.030	Dehydration (high), Overhydration (low)

Example: A urine sample with high specific gravity and positive protein may suggest dehydration and possible kidney dysfunction.

Additional info: For more detailed anatomical images and dissection guidance, refer to Appendix A of your lab manual.