Study Guide: Respiratory and Digestive Systems (Wet Exam Topics)

Respiratory System

Larynx and Trachea

The larynx and trachea are essential structures in the upper respiratory tract, responsible for air conduction, voice production, and airway protection.

• Hyoid Bone: A U-shaped bone in the neck that supports the tongue and serves as an attachment for muscles associated with swallowing and speech. It does not articulate directly with any other bone.

• Laryngeal Cartilages:

  • Thyroid Cartilage: The largest cartilage, forming the laryngeal prominence (Adam's apple).

  • Cricoid Cartilage: A ring-shaped cartilage located inferior to the thyroid cartilage; provides support and maintains airway patency.

  • Arytenoid Cartilages: Paired cartilages that anchor the vocal cords and are involved in voice production.

  • Epiglottis: A leaf-shaped cartilage that covers the glottis during swallowing, preventing food from entering the airway.

• Vestibular and Vocal Folds:

  • Vestibular Folds (False Vocal Cords): Superior folds that help close the glottis during swallowing.

  • Vocal Folds (True Vocal Cords): Inferior folds that vibrate to produce sound.

• Trachea: A flexible tube ("windpipe") supported by C-shaped cartilaginous rings, conducting air from the larynx to the bronchi.

Example: During swallowing, the epiglottis folds down to cover the glottis, preventing aspiration of food.

Lungs

The lungs are paired organs responsible for gas exchange. They are divided into lobes and separated by fissures.

• Fissures:

  • Left Oblique Fissure: Separates the superior and inferior lobes of the left lung.

  • Right Oblique Fissure: Separates the middle and inferior lobes of the right lung.

  • Right Horizontal Fissure: Separates the superior and middle lobes of the right lung.

• Apex: The pointed, superior portion of the lung, extending above the level of the first rib.

• Base: The broad, inferior surface of the lung resting on the diaphragm.

• Hilum: The medial region where bronchi, blood vessels, lymphatics, and nerves enter and exit the lung.

• Diaphragm: The primary muscle of respiration, separating the thoracic and abdominal cavities.

Example: The right lung has three lobes (superior, middle, inferior) while the left lung has two (superior, inferior) due to the position of the heart.

Digestive System

Peritoneal Structures

• Greater Omentum: A large, fatty peritoneal fold that hangs from the greater curvature of the stomach, covering the intestines and providing immune protection and fat storage.

• Epiploic Appendages: Small, fat-filled pouches of visceral peritoneum attached to the colon.

Stomach

The stomach is a muscular organ involved in mechanical and chemical digestion.

• Lesser Curvature: The shorter, concave border on the right side of the stomach.

• Greater Curvature: The longer, convex border on the left side.

• Cardia: The region where the esophagus enters the stomach.

• Fundus: The dome-shaped superior region.

• Body: The main, central region of the stomach.

• Rugae: Folds in the stomach lining that allow expansion as the stomach fills.

• Pyloric Part: The distal region leading to the small intestine.

• Pyloric Sphincter: A muscular valve controlling the passage of chyme into the duodenum.

Example: The rugae flatten as the stomach fills, allowing it to accommodate a large meal.

Small Intestine

• Duodenum: The first segment of the small intestine, receiving chyme from the stomach and secretions from the pancreas and liver.

• Hepatopancreatic Ampulla: A dilation where the bile duct and main pancreatic duct join and empty into the duodenum; important for the delivery of bile and pancreatic enzymes.

• Head of Pancreas: The expanded part of the pancreas nestled in the curve of the duodenum.

• Jejunum: The middle segment of the small intestine, specialized for nutrient absorption.

• Circular Folds (Plicae Circulares): Permanent folds in the mucosa and submucosa that increase surface area for absorption.

• Ileum: The final segment of the small intestine, ending at the ileocecal valve.

• Ileocecal Valve: A sphincter that regulates the flow of chyme from the ileum into the cecum of the large intestine.

Large Intestine

• Cecum: The first part of the large intestine, a pouch receiving material from the ileum.

• Colon: Divided into ascending, transverse, descending, and sigmoid sections.

• Hepatic Flexure: The right colic flexure, where the ascending colon turns to become the transverse colon near the liver.

• Splenic Flexure: The left colic flexure, where the transverse colon turns to become the descending colon near the spleen.

• Appendix: A narrow, worm-like tube attached to the cecum; contains lymphoid tissue.

• Rectum: The final section of the large intestine, leading to the anal canal.

Liver and Associated Ducts

• Falciform Ligament: A peritoneal fold attaching the liver to the anterior abdominal wall and diaphragm.

• Round Ligament (Ligamentum Teres): A remnant of the fetal umbilical vein, found in the free edge of the falciform ligament.

• Lobes: The liver is divided into left and right lobes by the falciform ligament.

• Common Hepatic Duct: Drains bile from the liver lobes and joins the cystic duct to form the bile duct.

• Bile Duct (Common Bile Duct): Carries bile from the liver and gallbladder to the duodenum.

• Main Pancreatic Duct: Transports pancreatic enzymes from the pancreas to the duodenum, joining the bile duct at the hepatopancreatic ampulla.

Table: Main Features of the Digestive Tract (Summary)

Region	Main Features	Function
Stomach	Cardia, fundus, body, pyloric part, rugae	Mechanical and chemical digestion
Small Intestine	Duodenum, jejunum, ileum, circular folds	Enzymatic digestion, nutrient absorption
Large Intestine	Cecum, colon, flexures, appendix, rectum	Water absorption, feces formation
Liver	Left/right lobes, falciform ligament, ducts	Bile production, metabolism
Pancreas	Head, main pancreatic duct	Enzyme and bicarbonate secretion

Additional info: The hepatopancreatic ampulla (of Vater) is a critical anatomical site where bile and pancreatic secretions mix before entering the duodenum. The greater omentum and epiploic appendages are important for immune defense and fat storage in the abdomen.