LAB 6: Digestive System Anatomy & Physiology

Organs Forming the Alimentary Canal

The alimentary canal is a continuous tube through which food passes, beginning at the mouth and ending at the anus.

• Mouth: Entry point for food; mechanical and chemical digestion begins.

• Pharynx: Passageway for food from mouth to esophagus.

• Esophagus: Muscular tube transporting food to the stomach.

• Stomach: Muscular organ for mixing and breakdown of food; contains gastric glands.

• Small Intestine: Major site of digestion and absorption; includes duodenum, jejunum, ileum.

• Large Intestine: Absorbs water and forms feces; includes cecum, colon, rectum, anus.

Accessory Digestive Organs and Functions

• Salivary glands: Secrete saliva containing enzymes for carbohydrate digestion.

• Liver: Produces bile for fat emulsification.

• Gallbladder: Stores and concentrates bile.

• Pancreas: Produces digestive enzymes and bicarbonate.

Microscopic Structures of the Stomach

• Mucosa: Contains gastric glands (parietal, chief, mucous cells).

• Muscularis externa: Three layers (longitudinal, circular, oblique) for churning food.

Small and Large Intestine Structure

• Small intestine: Villi and microvilli increase surface area for absorption.

• Large intestine: Haustra (pouches), taenia coli (longitudinal muscle bands).

Structural Differences: Rat vs. Human Digestive System

• Rats have a cecum adapted for cellulose digestion; humans have a smaller cecum.

• Arrangement and size of organs may differ.

Enzymes in Digestion

• Carbohydrate digestion: Amylase (salivary, pancreatic).

• Lipid digestion: Lipase (pancreatic).

• Protein digestion: Pepsin (stomach), trypsin and chymotrypsin (pancreas).

Bile Production, Storage, and Function

• Produced by: Liver

• Stored in: Gallbladder

• Function: Emulsifies fats, aiding digestion and absorption.

Digestion Experiment Reagents

• CHO Digestion: Lugol's iodine (tests for starch), Benedict's reagent (tests for reducing sugars).

• Protein Digestion: Biuret reagent (tests for peptide bonds).

• Lipid Digestion: Sudan Red stain (tests for lipids), Phenol red (pH indicator for fat digestion).

Interpretation of Results

• Lugol's iodine: Dark blue/black color indicates presence of starch; no color change means starch is absent.

• Benedict's reagent: Greenish to reddish-brown color indicates presence of monosaccharides/reducing sugars.

• Biuret reagent: Violet color indicates presence of proteins/peptides.

• Sudan Red: Stains lipids red, indicating their presence.

• Phenol red: Indicates pH change during fat digestion; yellow in acidic, red in neutral/basic.

Enzyme-Substrate Relationship

• Enzymes are biological catalysts that act on specific substrates to speed up chemical reactions.

• Factors affecting enzyme activity: temperature, pH, substrate concentration.

Emulsification and Absorption

• Emulsification: Bile salts break large fat globules into smaller droplets.

• Micelles: Small transport carriers in the intestine that enable absorption of lipids.

• Chylomicrons: Lipoprotein particles that transport absorbed fats through lymphatic system.

LAB 8: Urinary System Anatomy & Physiology

Organs Forming the Urinary System

• Kidneys: Filter blood, remove waste, regulate fluid and electrolyte balance.

• Ureters: Transport urine from kidneys to bladder.

• Urinary bladder: Stores urine.

• Urethra: Conducts urine out of the body.

Interior of Kidney and Regions

• Cortex: Outer region containing renal corpuscles and convoluted tubules.

• Medulla: Inner region with renal pyramids and collecting ducts.

• Renal pelvis: Funnel-shaped cavity collecting urine for passage to ureter.

Structure of a Nephron

• Renal corpuscle: Glomerulus and Bowman's capsule; site of filtration.

• Renal tubule: Proximal convoluted tubule, loop of Henle, distal convoluted tubule.

• Collecting duct: Final site for urine concentration.

Blood Supply of Kidney and Pathway of Blood Flow

• Renal artery → segmental arteries → interlobar arteries → arcuate arteries → interlobular arteries → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries/vasa recta → renal vein.

Pathway of Urinary Flow

• Nephron → collecting duct → minor calyx → major calyx → renal pelvis → ureter → bladder → urethra.

Urinalysis Test and Features of Normal Urine

• Normal urine: Pale yellow, clear, specific gravity 1.005–1.030, pH 4.5–8.0.

• Substances present: Water, urea, creatinine, uric acid, electrolytes.

• Substances absent: Glucose, protein, blood, ketones (presence may indicate pathology).

Table: Features of Normal vs. Abnormal Urine

Additional info:

• Enzyme activity is often measured by observing changes in color with specific reagents, indicating substrate breakdown.

• Urinalysis is a key diagnostic tool for assessing kidney function and detecting metabolic or systemic diseases.