Health and Disease 13
Learning opportunity 13: The Immune System
This learning opportunity has 4 tasks including exam style questions.
Target time: 40 minutes
Learning opportunity plan:
- Task 1- Starter
- Task 2- The immune system
- Task 3- How the immune system works
- Answers
- Task 4- Exam style questions
In this learning opportunity you will learn:
How to define antibody and antigen;
How to describe how lymphocytes work;
How to explain the difference between primary and secondary responses.
Key words:
Antibody
Antigen
Immune system
Lymphocyte
Pathogen
Phagocyte
You will need:
A pen
A piece of paper
A ruler and pencil
Task 1: Starter
Last learning session we looked at body defences.
Look at the diagram below. Decide which of the barriers are physical barriers and which are chemical barriers. Some of these barriers you may not have heard of, but use the definitions from last learning session to help you decide.
Task 2- The immune system
Revision tip:
This learning session has lots of new key words which sound similar to each other. Don’t worry if you do not remember them all straight away. Come back to this learning session a few times and practice using the words in a sentence to help get the hang of them.
Despite our body’s physical and chemical defences, some pathogens will find their way into our bodies. Our immune system fights the pathogens which are able to get past the defences.
Click the button below to read the BBC Bitesize summary of the immune system. Use the information to complete the table below.
| Part of the immune response | What is it? | What does it do? |
| Antigen | ||
| Lymphocyte | ||
| Antibody | ||
| Phagocyte | ||
| Memory lymphocyte |
Task 3- How the immune system works
Watch the video below and then put the stages of the immune response in order. You may also want to use diagrams to help you remember the stages better.
| A pathogen gets past the body’s natural defences. |
| The large number of antibodies in the blood destroys the pathogens. |
| A lymphocyte that has antibodies on its surface that match the antigens on the surface of the pathogen becomes activated. |
| In response to pathogens, your body produces white blood cells called lymphocytes. Lymphocytes have antibodies on their surface. |
| All pathogens have different shaped proteins on their surface called antigens. |
| White blood cells use the antigens to identify the pathogen as an invader. |
| An activated lymphocyte divides quickly to produce identical copies of itself. |
| Lymphocytes release antibodies into the blood. |
| In order to destroy the pathogen, the antibodies produced by a lymphocyte need to match the specific shape of the antigen on the pathogen’s surface. Creating a lymphocyte with the correct antibody takes time. |
Answers
Task 1 Answers
Physical barriers:
mucus and cilia
sticky mucus
Skin
blood clotting and wound repair
Chemical barriers:
bacteriostatic substances
secretions in sebaceous glands
pH and commensal organisms
tears and protective enzymes
acid in sweat
stomach acid
Task 2 Answers
| Part of the immune response | What is it? | What does it do? |
| Antigen | Protein on the surface of a pathogen. | Identifies the pathogen as an invader. |
| Lymphocyte | A type of white blood cell. | Detect pathogens and produce antibodies. |
| Antibody | A protein produced by lymphocytes. | Attacks and destroys antigens. |
| Phagocyte | A type of white blood cell. | Detect pathogens and engulf them, destroying the pathogen. |
| Memory lymphocyte | A type of lymphocyte. | ‘Remembers’ the antigens from an infection by a previous pathogen. Stops us becoming ill with the same pathogen twice. |
Task 3 Answers
| A pathogen gets past the body’s natural defences. |
| All pathogens have different shaped proteins on their surface called antigens. |
| White blood cells use the antigens to identify the pathogen as an invader. |
| In response to pathogens, your body produces white blood cells called lymphocytes. Lymphocytes have antibodies on their surface. |
| In order to destroy the pathogen, the antibodies produced by a lymphocyte need to match the specific shape of the antigen on the pathogen’s surface. Creating a lymphocyte with the correct antibody takes time. |
| A lymphocyte that has antibodies on its surface that match the antigens on the surface of the pathogen becomes activated. |
| An activated lymphocyte divides quickly to produce identical copies of itself. |
| Lymphocytes release antibodies into the blood. |
| The large number of antibodies in the blood destroys the pathogens. |
Take time to go back through the tasks, and make sure you have all the information you need. When you are ready, move on to the exam-style questions.
Task 4- Exam Style Questions
- The molecules on pathogens which cause an immune response are called:
- antigens
- bacteria
- antibodies
- lymphocytes
- Describe the role of lymphocytes in the immune response. (3 marks)
- Describe the difference between phagocytes and lymphocytes. (4 marks)
- Below is a table showing white blood cell counts for three patients after a recent blood test. Explain why the data shows person Z has had a bacterial infection.
When you are ready, click here to see the answers.
- 1. Antigen
- lymphocytes produce antibodies (1)
Which match the shape of antigens on pathogens (1)
and destroy the pathogen (1) - phagocytes engulf pathogens (1)
enzymes inside phagocytes break down pathogens (1)
lymphocytes recognise antigens on pathogens (1)
lymphocytes produce antibodies (1)
lymphocytes also produce antitoxins (1) - Person z has the highest number of white blood cells (1)
White blood cells are produced by the body in response to an invading pathogen/bacteria (1)