Human Digestive System

Science Unit: The Parts of the Human Digestive System

Lesson Objective

  • Students will be able to describe the parts of the digestive system and how these parts are adapted to digest food.

Warm Up: Starter Quiz

  1. Nutrition Question: Which 'N' is the N in MRS GREN? (Tick 1 correct answer)
       - Correct Answer: nutrition

  2. Food Chain Question: In a food chain, we could describe animals as which of the following? (Tick 1 correct answer)
       - Correct Answer: consumers

  3. Organs of the Digestive System Question: Which organs are part of the human digestive system? (Tick 3 correct answers)
       - Correct Answers: stomach, intestines, oesophagus

  4. Level of Organisation Question: Match the part of the body to the level of organisation in the body.
       - Organ: c (digestive)
       - Tissue: b (heart)
       - Muscle: a

  5. Function of Digestive System Parts Question: Match the parts of the digestive system with their function.
       - Teeth: a (chewing)
       - Stomach: b (digesting)
       - Intestines: c (digesting and absorbing)

Keywords

  • Digestion: The process of breaking down food into substances that can be absorbed into the blood.

  • Digestive System: A collection of organs that break down food.

  • Gland: A tissue or an organ that produces chemicals.

  • Adaptation: A feature that helps an organism to function and survive.

  • Fibre: Bulks up food so it can be moved through the digestive system more easily.

Lesson Outline

  • The human digestive system.

  • Adaptations of the organs, glands, and tissues.

  • Undigested food.

Explanation of Digestion

  • Purpose of Food: Food is our source of energy and also provides materials needed for growth and repair.

  • Digestion Process: The food consumed must be broken down into nutrients before it can be utilized for energy, growth, and repair. This process is called digestion.

Overview of the Digestive System

  • The digestive system consists of a group of organs that digest food, structured as follows:
      - Pathway of Food: From the Mouth to the Anus:
        1. Mouth
        2. Oesophagus
        3. Stomach
        4. Small intestine
        5. Large intestine
        6. Rectum
        7. Anus

Tasks

Task A: Label the Diagram of Digestive System Organs

  • Main organs to label: mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus.

Task A Feedback

  • Correct labeling includes: mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus.

Task A: Complete the Flowchart of Digestion Order

  • Correct flow through digestive organs:
      1. Mouth
      2. Oesophagus
      3. Stomach
      4. Small intestine
      5. Large intestine
      6. Rectum
      7. Anus

Detailed Explanation of Digestive Organs

  1. Mouth:
       - Adaptations: Salivary glands, tongue, teeth
         - Teeth: Cut and chew food into smaller pieces.
         - Tongue: Rolls and mixes food in the mouth.
         - Salivary glands: Produce chemicals and add water to food.

  2. Oesophagus:
       - Adaptation: Rings of muscle (peristalsis) contract behind the bolus to push food down to the stomach.
       - Peristalsis: The process of muscle contraction that moves food through the digestive tract.

  3. Stomach:
       - Function: Receives recently swallowed food and produces hydrochloric acid that enables food to be digested and kills pathogens.

  4. Small Intestine:
       - Characteristics: A long, narrow tube that slows down food passage to ensure complete digestion and absorption of nutrients into the blood.
       - Villi: Tiny structures on the inside surface that absorb nutrients into the blood.

  5. Pancreas:
       - Role: A gland that secretes chemicals into the small intestine, breaking down food into nutrients.
       - Note: Food does not pass through the pancreas.

  6. Liver:
       - Function: Also a gland that secretes bile into the small intestine, helping to break down fat and suspend it in water.
       - Note: Food does not pass through the liver.

Function and Importance of the Large Intestine

  • Role: Receives undigested food from the small intestine and absorbs water into the blood.

  • Importance of Fibre: Helps move food through the digestive system; undigested waste is passed as faeces.

Storing and Exiting Waste

  • Rectum: Stores faeces until they are ready to be expelled from the body.

  • Anus: A ring of muscle that controls the exit of faeces and gases.