Y8 Review of Digestive System

Systems of the Human Body

  • Overview of the Digestive System

Introduction

  • Digestive System Functionality:

    • Responsible for obtaining food and eliminating waste.

Digestive System Components

  • Mouth:

    • Breaks up food and initiates chemical digestion.

  • Pharynx:

    • Responsible for swallowing food.

  • Esophagus:

    • Transports food via peristalsis.

  • Stomach:

    • Stores and churns food, adding hydrochloric acid.

  • Small Intestine:

    • Absorbs nutrients and water.

  • Large Intestine:

    • Absorbs water and ions, storing waste.

  • Rectum:

    • Stores and expels feces.

  • Anus:

    • Opening for fecal elimination (Egestion).

  • Liver:

    • Produces bile; stores glucose (as glycogen) and vitamins.

  • Gallbladder:

    • Stores and concentrates bile to neutralize stomach acid.

  • Pancreas:

    • Regulates blood glucose levels.

Digestion in the Mouth

  • Teeth:

    • Different types of teeth aid in breaking down food mechanically.

    • Involved in physical digestion through chewing.

  • Saliva Production:

    • Produced in the mouth to facilitate both physical and chemical digestion.

    • Contains the enzyme amylase, which breaks down carbohydrates.

Types of Teeth

  • Types of Teeth:

    1. Incisors:

      • Sharp and designed for cutting.

    2. Canines:

      • Pointed and used for tearing food.

    3. Premolars:

      • Have flat surfaces for crushing food.

    4. Molars:

      • Large and flat, used for grinding food.

  • Physical Digestion:

    • Each tooth plays a role in facilitating the breakdown of food.

Role of Saliva

  • Saliva Functions:

    • Softens food for easier swallowing.

    • Contains amylase enzyme aiding in the breakdown of carbohydrates.

    • Helps to form a bolus (a rolled ball of food) before swallowing.

Digestion and Absorption in the Small Intestine

  • Small Intestine:

    • Continues the physical digestion started in the stomach.

    • Absorption of digested nutrients occurs mainly here.

  • Villi:

    • Small finger-like projections that increase surface area for absorption.

    • Only smaller molecules (e.g., glucose) can diffuse into the blood from the small intestine through the villi, moving from areas of higher to lower concentration.