Our Body's defences against Infectious Diseases
Reference: Core Science Stage 5 Section 2.3) Putting Up Defences pg 50 - 51
Task 1: Our Body's Lines of Defence
View the clickview program "Battle Scars" and complete the worksheet. First Line of Defence - stop the pathogen entering your body using skin as well as little hairs, mucus, salvia, tears etc to trap and remove foreign particles. Second Line of Defence - White blood cells called phagocytes destroy pathogens that enter the blood stream Third Line of Defence - White Blood Cells called lymphocytes inactivate, engulf and then destroy pathogens. |
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You may feel that you need a little more clarification on our body's line of defence. This is a great video produced by a student to help strengthen your understanding. |
3.3.2) A Closer Look at our First Line of Defence
3.3.3) A Closer Look at our Second Line of Defence
3.3.4) A Closer Look at our Third Line of Defence
The Third Line of Defence involves a system that is very similar to our veins and arteries. It is called the Lymphatic system. The primary function of the lymphatic system is to transport lymph, a clear, colourless fluid containing white blood cells that helps rid the body of toxins, waste and other unwanted materials. Excellent Article on the Lymphatic System by LiveScience. The diagram on the right shows white blood cells attacking a cancer cell.
1. There are many different types of lymphocytes that have ANTIBODIES that will detect a particular pathogen. Antibodies are chemicals on the lymphocyte that disable pathogen (or sometimes are called antigens).
2. Pathogen invades our body and enters the blood. An example is the Influenza Virus. 3. This triggers our body's Third Line of Defence and lymphocyte B has the right antibodies to bind to the pathogen and make it inactive. 4. Now the pathogen can be engulfed and destroyed by other lymphocytes!! |
Lines of Defence Role Play
Create your own video / cartoon / role play to explain the three lines of defence in small groups of 3-4 students. * Make sure you include examples of each of the three lines of defence and describe how they protect us from disease. * You must use the provided labels to help clarify your role play. |
Extension Task 2: Leukocytes
Learn about the functions of different types of leukocytes by viewing Why You Are Still Alive. Create a flow chart or diagram to summarise the different types of leukocytes and their roles in the immune system |