Digestive System Overview

• Instructor: Rob Evans, Prifysgol Wrecsam, Wrexham University

Learning Outcomes

• Anatomical Structures: Identify components making up the digestive system.

• Physiological Functions: Describe the mechanisms and functions of the digestive system.

• Pathophysiological Changes: Explain changes due to common digestive illnesses, diseases, injuries, and well-being conditions.

What is the Digestive System?

• The digestive system includes:

  • Alimentary Canal: Digestive tract.

  • Accessory Organs: Organs contributing to digestion.

• Purpose:

  • Breaks down complex food into absorbable units.

  • Facilitates absorption into circulation for use by body cells.

Key Components of the Digestive System (Page 4-5)

• Anatomy:

  • Soft palate, hard palate, salivary glands, tongue, oropharynx, larynx, esophagus, stomach, small intestine, large intestine, diaphragm, liver, gall bladder, pancreas, duodenum.

• Organs Include:

  • Major Components: Stomach, small & large intestines, liver, pancreas.

  • Structure: Includes various sections like ascending colon, jejunum, ileum, etc.

Digestive Processes (Page 10)

1. Intake of Nutrients

• Functions:

  • Intake is crucial for health.

  • Provides nutrients essential for energy, cell division, growth, and repair.

2. Elimination of Wastes

• Waste excretion of indigestible food and microbes. !

Breakdown of Food (Page 11)

Processes Involved:

• Mechanical: Chewing food into smaller pieces.

• Chemical: Enzymatic breakdown for absorbability.

• Nutrient Function: Provide building blocks for new cells, hormones, and enzymes.

Waste Elimination (Page 12)

• Nature of Elimination:

  • In infants: Involuntary.

  • In adults: Voluntary.

• Composition:

  • 60-70% water, fiber, fatty acids, mucus.

Alimentary Canal and Accessory Organs (Page 13-16)

Alimentary Canal

• Length: 9-10 meters in average adults.

• Function:

  • Connecting mouth to anus for digestion.

Accessory Organs

• Include salivary glands, pancreas, liver.

• Functions:

  • Produce enzymes for digestion, release bile to assist in fat digestion.

Stomach Functions (Page 21)

• Storage: Temporary storage of food.

• Digestion: Both chemical and mechanical processes.

• Regulation: Controls passage into the duodenum.

Absorption of Nutrients (Page 26)

• Surface Area: Increased by villi and microvilli.

• Mechanisms: Includes diffusion, osmosis, facilitated diffusion, active transport.

• Nutrient Distribution:

  • Nutrients go into blood capillaries; fats to the lymphatic system.

Saliva and Its Role (Page 28)

• Volume: Approximately 1500 mL enters GI tract.

• Components: Includes water, gastric juice, bile, and pancreatic juice.

Accessory Organs (Page 29-33)

1. Salivary Glands

• Function: Chemical digestion, mouth lubrication.

2. Pancreas

• Produces digestive enzymes for macronutrients and insulin.

3. Liver

• Functions include metabolism of nutrients, protein synthesis, and detoxification.

4. Biliary Tract

• Stores and releases bile for digestion.

Case Study: Tom (Pages 35-38)

• Patient Details: 56-year-old male with symptoms including dysphagia, heartburn, abdominal pain, and weight loss.

• Medical Investigation: Statement about pathophysiology, presenting issues, and the impact of oesophageal cancer on digestion.

Activity and Discussion (Pages 39-42)

• Engage with case study findings, discussing how Tom's digestive system is affected by his condition.