Digestion Flashcards

Digestion Overview

• Digestion is the process of breaking down food into usable forms.
• Types of digestion include intracellular (within cells) and extracellular (outside cells).

Types of Digestion

• Intracellular digestion: Occurs inside the cell; enzymes break down food into small molecules (e.g., plants).
• Extracellular digestion: Takes place outside the cell with enzymes secreted into a digestive cavity (e.g., animals).

Digestive Systems in Animals

• Animals possess two digestive systems:
  • Incomplete digestive system: Features a single opening (e.g., starfish).
  • Complete digestive system: Contains two openings (mouth and anus) (e.g., earthworm).

Digestion Process Parts

• Digestion comprises two parts:
  • Physical digestion: Breaking down large pieces into smaller ones (mechanical process) (e.g., gizzards in earthworms and birds).
  • Chemical digestion: Involves breaking complex molecules into smaller units (carbohydrates, lipids, proteins).

Digestive Organs and Functions

• Mouth: Initiates food ingestion and physical digestion; begins carbohydrate digestion using salivary amylase.
• Esophagus: A muscular tube that uses peristalsis to transport food to the stomach.
• Epiglottis: A flap that covers the trachea to prevent food from entering the airway.
• Stomach:
  • Breaks down food into a paste (chyme).
  • Contains hydrochloric acid (pH ~2) and produces gastrin for acid stimulation.
  • Secretes pepsin for protein digestion and has a mucus lining for protection.
• Pancreas:
  • Produces pancreatic juice to regulate intestinal pH (~8).
  • Releases enzymes, including amylase (carbohydrates), trypsin (proteins), and lipase (lipids), into the small intestine.
• Liver: Produces and releases bile, which emulsifies fats for easier digestion.
• Gall Bladder: Stores bile; may develop gallstones.

Small and Large Intestine Functions

• Small intestine:
  • Main site for nutrient absorption through villi.
  • Maintains a basic environment (pH ~8).
  • Produces secretin to stimulate pancreatic juice secretion.
• Large intestine:
  • Primarily absorbs water and forms waste for egestion.

Absorption and Digestion Details

• Most water absorption occurs in the large intestine.
• The large intestine is crucial for maintaining low water content in feces.
• Small intestine is the main site for absorbing digestive end products into the bloodstream.
• If the stomach is surgically removed, protein digestion would begin in the small intestine.
• Substances aiding digestion in the small intestine include bile, pancreatic juice, and intestinal juice.

Miscellaneous Concepts

• Peristalsis is essential for moving food through the gastrointestinal tract; its cessation affects digestion.
• Enzymes that hydrolyze fats are called lipases.
• Emulsification is the process converting fat globules into smaller fat droplets, enhancing digestion.

Test your knowledge on the process of digestion with these flashcards. Learn about the two types of digestion, intracellular and extracellular, and their definitions. Perfect for students looking to grasp the fundamentals of digestion.