Gastroenterology & Gastrointestinal (GI) System

Introduction to Gastroenterology

Gastroenterology is the medical specialty focused on the anatomy, physiology, and diseases of the gastrointestinal (GI) system. Gastroenterologists diagnose and treat disorders using diagnostic tests, medical and surgical procedures, and pharmacological interventions.

• Gastroenterology: Gastr/o = stomach, Enter/o = intestine, -logy = study of

• The GI system is a continuous pathway of organs and glands responsible for digestion, absorption, and elimination of waste.

Upper GI System Anatomy

The upper GI system includes the oral cavity, pharynx, esophagus, and stomach. Each structure plays a role in the initial stages of digestion and the movement of food.

• Oral Cavity: Contains teeth, gums, tongue, hard palate, and soft palate.

• Pharynx: Common passageway for air and food.

• Esophagus: Muscular tube connecting pharynx to stomach; peristalsis moves food downward.

• Peristalsis: Involuntary, wave-like muscle contractions moving food through the digestive tract.

Salivary Glands

Salivary glands secrete saliva, which begins the process of chemical digestion and lubricates food for swallowing. There are three major pairs:

• Parotid glands: Anterior to the ear

• Sublingual glands: Beneath the tongue

• Submandibular glands: Inferior to the mandible

The Stomach

The stomach is an elongated sac divided into four regions: cardia, fundus, body, and pylorus. It serves as a reservoir for food, initiates protein digestion, and regulates the passage of chyme into the small intestine.

• Lower esophageal sphincter: Prevents reflux of stomach contents

• Pyloric sphincter: Controls passage of chyme into the duodenum

• Rugae: Folds in the gastric mucosa that allow expansion

Small and Large Intestines

The small intestine is the primary site for digestion and absorption, divided into the duodenum, jejunum, and ileum. The large intestine absorbs water and forms feces, consisting of the cecum, colon (ascending, transverse, descending, sigmoid), rectum, and anus.

• Villi: Finger-like projections in the small intestine that increase surface area for absorption

• Haustra: Pouches in the colon that expand to accommodate waste

Accessory Organs: Liver, Gallbladder, Pancreas

Accessory organs secrete substances essential for digestion. The liver produces bile, the gallbladder stores and concentrates bile, and the pancreas secretes digestive enzymes and hormones.

• Liver: Produces bile, metabolizes nutrients, detoxifies substances

• Gallbladder: Stores and concentrates bile, releases it into the duodenum

• Pancreas: Secretes amylase, lipase, and proteases; also produces insulin

Digestive Processes

Digestion involves mechanical and chemical processes. Mechanical digestion includes mastication, deglutition, and peristalsis. Chemical digestion involves enzymes and acids breaking down food into absorbable molecules.

• Amylase: Breaks down carbohydrates

• Lipase: Breaks down fats

• Pepsin: Breaks down proteins

• Intrinsic factor: Essential for vitamin B12 absorption

Absorption and Elimination

Absorption is the process by which nutrients and water enter the bloodstream, primarily in the small intestine. Elimination removes undigested waste as feces through the rectum and anus.

Common Diseases and Disorders of the GI System

Diseases can affect any part of the GI tract, including:

• Anorexia: Loss of appetite

• Dysphagia: Difficulty swallowing

• Gastroesophageal reflux disease (GERD): Chronic acid reflux

• Peptic ulcer disease (PUD): Ulceration of the stomach or duodenal mucosa

• Inflammatory bowel disease (IBD): Chronic inflammation (e.g., Crohn's disease, ulcerative colitis)

• Hernias: Protrusion of intestine through a weak spot in the abdominal wall

• Hepatitis: Inflammation of the liver, often viral

• Cholelithiasis: Gallstones

• Pancreatitis: Inflammation of the pancreas

Diagnostic and Laboratory Procedures

Diagnosis of GI diseases involves laboratory tests (e.g., liver function tests, fecal occult blood test), imaging (e.g., CT, MRI, ultrasound), and endoscopic procedures (e.g., colonoscopy, endoscopy).

Medical and Surgical Treatments

Treatments include medications (antacids, antibiotics, antidiarrheals, antiemetics, laxatives, proton pump inhibitors), and surgical procedures (appendectomy, cholecystectomy, bowel resection, herniorrhaphy, liver transplantation).

Pulmonology: Respiratory System

Introduction to Pulmonology

Pulmonology is the medical specialty concerned with the anatomy, physiology, and diseases of the respiratory system. Pulmonologists diagnose and treat respiratory disorders using clinical, laboratory, and imaging techniques.

• Pulmon/o = lung, -logy = study of

Anatomy of the Respiratory System

The respiratory system is divided into upper and lower tracts, each with specialized structures for air conduction, filtration, and gas exchange.

Upper Respiratory System

• Nose and Nasal Cavity: Filters, warms, and humidifies air; lined by nasal mucosa and cilia

• Turbinates: Bony projections that increase surface area and slow airflow

• Pharynx: Common passageway for air and food; divided into nasopharynx, oropharynx, and laryngopharynx

Lower Respiratory System

• Larynx (voice box): Contains vocal cords, routes air and food appropriately

• Trachea (windpipe): Supported by C-shaped cartilage rings; divides into right and left bronchi

• Bronchi and Bronchioles: Conduct air into the lungs; bronchioles lack cartilage and have smooth muscle

• Lungs: Right lung has three lobes, left lung has two; contain alveoli for gas exchange

• Alveoli: Spherical sacs where oxygen and carbon dioxide are exchanged with capillaries; secrete surfactant to prevent collapse

Thoracic Cavity and Pleura

• Thorax: Bony cage formed by the ribs, sternum, and spine

• Mediastinum: Central compartment containing the heart, trachea, and esophagus

• Diaphragm: Main muscle of respiration, separates thoracic and abdominal cavities

• Pleura: Double-layered membrane surrounding each lung; pleural fluid reduces friction during breathing

Key Terms and Word Breakdowns

• Nas/o- = nose

• Pharyng/o- = pharynx

• Laryng/o- = larynx

• Trache/o- = trachea

• Bronch/o- = bronchus

• Pneum/o-, Pulmon/o- = lung

• Alveol/o- = alveolus

• Pleur/o- = pleura

• Diaphragm: Main muscle of respiration

Summary Table: Major GI and Respiratory Structures

Additional info: This guide expands on the provided notes with definitions, examples, and logical groupings to ensure a comprehensive, self-contained study resource for medical terminology students.