Digestive Process Lecture Notes

Overview of Digestion

• Mouth: Start of digestion.
• Esophagus:
  • Tube-like channel, approximately 20 cm long.
  • Connects oral cavity to stomach.
  • Peristalsis: Squeezing motion that pushes food to the stomach.

Stomach

• Function: Most elastic part of the digestive system.
• Location: Upper left abdominal cavity.
• Digestion Types:
  • Mechanical Digestion: Stomach wall/muscles squeeze and stir food.
  • Chemical Digestion:
    • Gastric Juices: Produced by gastric glands.
      • Contains:
        • Pepsin: Breaks down proteins into peptones.
        • Renin: Precipitates milk protein into casein.
        • Hydrochloric Acid (HCl): Acidifies food and kills germs.

Small Intestine

• Length: 6 to 7 meters; longest part of the digestive tract.
• Parts of the Small Intestine:
  1. Duodenum (12-finger intestine):
     • Length: ~25 cm.
     • Digests food with pancreatic juices and bile.
     • Pancreatic Enzymes:
       • Amylase: Converts starch into glucose.
       • Trypsin: Converts peptones into amino acids.
       • Lipase: Converts fats into fatty acids.
  2. Jejunum:
     • Length: ~2.5 m.
     • Digests food from the duodenum.
  3. Ileum:
     • Absorbs food juices; has blood vessels that circulate nutrients.

Large Intestine

• Function: Absorbs fluids, vitamins, and minerals from remaining food.
• Bacteria: E. coli aids in the spoilage of food remnants to produce feces.
• Feces: Excreted through the anus.

Rectum and Anus

• Rectum: Temporary storage for feces.
• Nerve Response: Signals brain for defecation when filled.
• Anus: Exit point for feces.

Discussion Points

• Heartburn: Mentioned as a topic for the next discussion.
• Energy from Digestion: Juices convert food into energy.
• Personal Experience: Mention of stomachaches to be discussed later.