A&P II Lab Exam 2 Study Guide: Lymphatic, Respiratory, and Digestive Systems

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Lymphatic System

Overview of Lymphatic Structures

The lymphatic system is a network of vessels, nodes, and organs that helps maintain fluid balance, absorb fats, and defend the body against pathogens. Key structures include lymph nodes, lymphatic vessels, and specialized organs.

Lymphatic Organs: Lymph nodes, spleen, thymus, and Peyer's patches.
Lymphatic Vessels: A network of capillaries and larger vessels that transport lymph.
Major Lymph Nodes: Cervical, axillary, and inguinal nodes.
Lymphatic Trunks and Ducts: Collect lymph from regions of the body and drain into the venous system (e.g., thoracic duct, right lymphatic duct).

Histology of Lymphatic Organs

Microscopic examination of lymphatic tissues reveals specialized structures for immune function.

Lymph Node: Contains cortex (with lymphoid follicles) and medulla; filters lymph and houses lymphocytes.
Spleen: Red pulp (filters blood, removes old RBCs) and white pulp (immune response).
Peyer's Patches: Aggregated lymphoid nodules in the small intestine; monitor intestinal bacteria.

Functions of Lymphatic Organs

Lymph Node: Filters lymph, initiates immune responses.
Spleen: Filters blood, recycles iron, stores platelets, mounts immune responses.
Peyer's Patches: Protect the intestinal tract from pathogens.
Thymus: Site of T lymphocyte maturation.

Respiratory System Anatomy

Identification of Respiratory Structures

The respiratory system consists of organs and structures involved in gas exchange and air conduction.

Nasal Conchae: Increase surface area for warming and humidifying air.
Paranasal Sinuses: Lighten skull, produce mucus, resonate sound.
Pharynx Regions: Nasopharynx, oropharynx, laryngopharynx; conduct air and food.
Epiglottis: Prevents food from entering the trachea during swallowing.
Hyaline Cartilage Rings: Maintain tracheal patency.
Alveoli: Site of gas exchange in the lungs.

Histology of Respiratory Organs

Trachea: Lined with pseudostratified ciliated columnar epithelium and goblet cells; supported by hyaline cartilage.
Alveoli: Simple squamous epithelium for efficient gas exchange.
Bronchiole: Lined with ciliated columnar or cuboidal epithelium; lack cartilage.

Pleurae and Pleural Cavity

Parietal Pleura: Lines the thoracic cavity.
Visceral Pleura: Covers the lungs.
Pleural Cavity: Space between pleurae; contains pleural fluid to reduce friction during breathing.

Respiratory Physiology

Pulmonary Volumes and Capacities

Respiratory volumes and capacities are measurements of air movement in the lungs.

Tidal Volume (TV): Volume of air inhaled or exhaled in a normal breath. (Typical value: ~500 mL)
Inspiratory Reserve Volume (IRV): Additional air that can be inhaled after a normal inspiration.
Expiratory Reserve Volume (ERV): Additional air that can be exhaled after a normal expiration.
Residual Volume (RV): Air remaining in lungs after maximal exhalation.
Vital Capacity (VC): Maximum amount of air exhaled after maximal inhalation.
Total Lung Capacity (TLC): Total volume of the lungs after maximal inspiration.

Key Equations:

Muscles of Respiration

Inspiration: Diaphragm and external intercostal muscles contract.
Expiration: Usually passive; internal intercostals and abdominal muscles active during forced expiration.

Pressure Relationships

Ppul (Intrapulmonary Pressure): Pressure within the alveoli.
Patm (Atmospheric Pressure): Pressure of air outside the body.
During Inspiration: (air flows in)
During Expiration: (air flows out)

Digestive System: Anatomy & Physiology

Identification of Digestive Structures

The digestive system includes organs for ingestion, digestion, absorption, and elimination.

Salivary Glands: Secrete saliva containing amylase for carbohydrate digestion.
Liver: Produces bile, processes nutrients.
Hepatic Portal Vein: Transports nutrient-rich blood from GI tract to liver.
Gall Bladder: Stores and concentrates bile.
Acinar Cells (Pancreas): Secrete digestive enzymes.
Duodenum: First part of small intestine; site of chemical digestion.
Goblet Cells: Secrete mucus in the GI tract.
Duodenal (Brunner's) Glands: Secrete alkaline mucus to neutralize stomach acid.

Histology of Digestive Organs

Esophagus: Stratified squamous epithelium; muscularis for peristalsis.
Stomach: Simple columnar epithelium; gastric pits and glands.
Small Intestine (Duodenum): Villi and microvilli for absorption; goblet cells.
Liver: Hepatocytes arranged in lobules; portal triads at corners.
Pancreas: Acinar cells (exocrine), islets of Langerhans (endocrine).

Layers of the Alimentary Canal

The wall of the alimentary canal has four major tunics/layers, each with specific tissue types and functions.

Layer	Tissue Type	Function
Mucosa	Epithelium, lamina propria, muscularis mucosae	Secretion, absorption, protection
Submucosa	Connective tissue with blood vessels, nerves	Nutrition, support, protection
Muscularis Externa	Smooth muscle (circular & longitudinal)	Peristalsis, segmentation
Serosa (or Adventitia)	Connective tissue, mesothelium	Protection, reduces friction

Portal Triad of the Liver

Components: Branch of hepatic artery, branch of hepatic portal vein, bile duct.

Microanatomy of the Liver

Liver Lobules: Hexagonal units with central vein.
Portal Triad: At each corner of lobule.
Hepatic Portal Vein: Brings nutrient-rich blood.
Hepatic Arteriole: Supplies oxygenated blood.
Bile Duct: Drains bile produced by hepatocytes.
Liver Sinusoid Capillaries: Allow exchange between blood and hepatocytes.
Stellate Macrophages (Kupffer Cells): Remove debris and pathogens.

Digestive Enzymes: Sources and Functions

Enzyme	Source	Function
Amylase	Salivary glands, pancreas	Breaks down starch to maltose
Pepsin	Stomach (chief cells)	Digests proteins to peptides
Trypsin	Pancreas	Continues protein digestion in small intestine
Lipase	Pancreas	Breaks down triglycerides to fatty acids and glycerol
Brush Border Enzymes	Small intestine	Final digestion of carbohydrates and proteins

Laboratory Tests for Digestion

Carbohydrate Digestion:
- Lugol’s Iodine: Tests for starch (positive: blue-black; negative: yellow-brown).
- Benedict’s Reagent: Tests for reducing sugars (positive: orange/red; negative: blue).
Protein Digestion:
- Biuret Solution: Tests for peptide bonds (positive: violet; negative: blue).
Lipid Emulsification:
- Sudan Red Stain: Stains lipids (positive: red droplets; negative: no color change).
Lipid Digestion:
- Phenol Red Indicator: Detects pH change as fatty acids are released (color shifts from red to yellow as pH decreases).

Additional info:

Students should review both anatomical models and histology slides for identification tasks.
Understanding the function and structure of each organ is essential for lab practical exams.