Digestive System Vocabulary Flashcards

Introduction to the Digestive System

• Purpose of the Digestive System: Converts food into basic organic molecules necessary for ATP production, tissue building, and cofactor/coenzyme functions.
• Key Processes:
  • Digestion: Breakdown of polymers (carbohydrates, fats, proteins) into monomers via hydrolysis reactions.
  • Absorption: Uptake of monomers into bloodstream for cellular use.

Structure and Function of the Digestive Tract

• Digestive Tract: Continuous tube from mouth to anus, considered outside the body as it opens at both ends.
• Functions of the Digestive Tract:
  1. Motility: Movement of food.
  • Ingestion, Mastication, Deglutition, Peristalsis, Segmentation.
  1. Secretion:
  • Exocrine: Digestive enzymes, HCl, mucus, water, bicarbonate.
  • Endocrine: Hormones regulating digestion.
  1. Digestion: Breakdown of food into smaller units.
  2. Absorption: Uptake of nutrients into blood or lymph.
  3. Storage and Elimination: Temporary storage of undigested food, elimination of waste.
  4. Immune Barrier: Tight junctions in epithelium prevent pathogen entry.

Divisions of the Digestive System

• Gastrointestinal Tract: ~30 feet long, includes:
  • Oral cavity, Pharynx, Esophagus, Stomach, Small Intestines, Large Intestines, Anus.
• Accessory Organs: Teeth, tongue, salivary glands, liver, gallbladder, pancreas.

Layers of the Alimentary Tract

1. Mucosa: Inner layer, secretory and absorptive with folded surface (villi).
2. Submucosa: Vascular layer with glands, nerve plexuses.
3. Muscularis: Smooth muscle responsible for motility; contains myenteric plexus.
4. Serosa: Outer protective layer covering organs.

Regulation of the GI Tract

• Monitored by:
  • Parasympathetic Division: Stimulates digestion (via vagus nerve).
  • Sympathetic Division: Reduces digestive activity.
  • Hormones: Released from digestive organs for regulation.
  • Intrinsic Regulation: Enteric nervous system manages gut function independently.

Digestive Process from Mouth to Stomach

A. Mouth

• Mastication: Chewing mixes food with saliva, forming a bolus.
• Saliva Components: Mucus, antimicrobial agents, salivary amylase.
• Deglutition: Three phases:
  1. Oral (voluntary).
  2. Pharyngeal (involuntary, automatic).
  3. Esophageal (peristalsis moves food to stomach).

B. Esophagus

• Length: About 10 inches.
• Conducts food to stomach; lined with stratified squamous epithelium; sphincter prevents regurgitation.

C. Stomach

1. Functions:
   • Stores food, churns for mixing, initiates protein digestion.
2. Regions: Cardiac, Fundus, Body, Pyloric (with sphincter).
3. Gastric Secretions:
   • Mucus (protection), HCl (digestion, kills bacteria), Pepsinogen (activated to pepsin).
4. Digestive Defenses:
   • Mucosal barrier prevents self-digestion.
5. Absorption in Stomach: Limited to alcohol and NSAIDs.

Peptic Ulcers and Gastritis

• Peptic Ulcers: Erosions caused primarily by Helicobacter pylori.
• Acute Gastritis: Inflammation triggered by acid, requires treatment with antacids or medications.

Digestion and Absorption in the Small Intestine

Structure

• Length: 12 ft, divided into three sections: duodenum, jejunum, ileum.
• Villi and Microvilli: Increase surface area for nutrient absorption.

Functions

1. Digestion Completion: For carbohydrates, proteins, fats occurs here.
2. Enzymatic Action: Brush border enzymes complete digestion before absorption.
3. Nutrient Absorption:
   • Monosaccharides, amino acids, fatty acids absorbed via specific transport mechanisms.

Large Intestine Overview

1. Structure: Cecum, colon (ascending, transverse, descending, sigmoid), rectum, anus.
2. Primary Functions: Water and electrolyte absorption, storing feces, microbial production of vitamins.

Liver, Gallbladder, and Pancreas

Liver Functions

• Bile Production: Emulsifies fats, aids in digestion.
• Detoxification: Filters blood, removes toxins, metabolizes drugs.
• Metabolic Regulation: Manages glucose, fat, and protein levels.

Gallbladder

• Function: Stores and concentrates bile for fat digestion.
• Pathway: Bile flows from liver → gallbladder → duodenum.

Pancreas

• Exocrine Function: Produces digestive enzymes and bicarbonate to neutralize stomach acid.
• Endocrine Function: Insulin production for glucose regulation.

Hormones and Regulation of Digestion

• Key Hormones: Gastrin, CCK, Secretin, GIP. Each plays a role in digestive process regulation and integration of gastric and intestinal function.

Common Digestive Disorders

• Inflammatory Bowel Disease (IBD): Crohn's disease and ulcerative colitis. Symptoms include chronic diarrhea, abdominal pain.
• Irritable Bowel Syndrome (IBS): Affects gut motility and function, leading to discomfort that can relate to stress, diet, or dysregulated microbiota.

Conclusion

• Understanding the complexity of the digestive system is critical for recognizing its role in overall health and identifying conditions that may arise due to dysfunctions in these processes.