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Describe the Role of the Immune System

Worksheet Overview

QUESTION 1 of 10

Did you know that the human body comes across hundreds and thousands of potential pathogens every day?

 

Image of bacteria, virus and fungi

 

The human body has loads of clever defences to protect itself from these invaders! These are called non-specific defences because they target any pathogen and aren't specific to a particular type. Let's look at these in more detail below.

 

Image of bacteria

 

The First Line of Defence:


Physical Defences

The first line of defence is the skin. The skin is very tough and it pretty much covers the whole body. A pathogen has to get past the skin in order to get inside the body where conditions are great for replication. It does this in places such as a cut in the skin, for example. This is a physical barrier.

Another physical barrier is found in the nose. The hairs found in your nose help to trap any dust particles that may be a source of pathogens.

 

Image of ciliated cells

 

Mucus is another physical barrier. Mucus is produced by special cells found in the trachea and bronchi (the tubes that branch into the lungs).  It’s thick and sticky and perfect for trapping pathogens. The trachea is lined with special cells called ciliated cells. These contain tiny hairs which move backwards and forwards. This moves mucus out of the airways into your mouth (ready to be spat out or swallowed), a bit like a broom sweeping up a mess!


Chemical Defences

If a pathogen is sneaky enough to get past all of these physical barriers, our body uses chemical barriers to further prevent infection. So what are these chemical barriers?

 

Image of eye

 

 

Enzymes, called lysozymes, in our eyes and saliva are an example of a chemical barrier. These enzymes are great at protecting us because they destroy any pathogen that tries to sneak in through our eyes or mouth.

Another example is the hydrochloric acid found in our stomach. This acid is very strong and can destroy pathogens that make their way to the stomach in food and drink. This is known as a chemical barrier.


So what happens if a pathogen gets past our first line of defence? This is where the immune system steps in - our second line of defence.


 

The Second Line of Defence:


The immune system is made up of different types of cells. One type of cell is called the white blood cell.

 

Image of antigens and antibody

 

 

Pathogens get into the body through bypassing the body's first line of defence. Pathogen cells have markers on their surface called antigens. Each pathogen has different antigens. White blood cells called phagocytes recognise these foreign antigens and will engulf and destroy these pathogens. This process is called phagocytosis.

Other white blood cells, called lymphocytes, make proteins called antibodies that fit the antigens of a pathogen like a puzzle. The antibodies stick to the pathogen’s antigens allowing them to be clumped together.  This makes it easier for the pathogen to be detected and destroyed by phagocytes.

Some pathogens will produce toxins that make you feel ill. Lymphocytes can produce specific antitoxins that will neutralise the toxin.


 

Immunity


If you get chickenpox when you’re young, you can’t get it again. Your body has developed an immunity to the disease. 

After you have been infected with the chickenpox virus, some of the white blood cells that made antibodies against it stay in your blood. These are called memory cells.

If you’re infected again, the memory cells reproduce and make antibodies very quickly, so your immune system responds much faster the second time.

You destroy the pathogen before it can make you ill.

 

 

In the following activity, you will describe how the body protects itself from disease​. 

White blood cells make antibodies with shapes that fit the antigens. Other white blood cells can then find and destroy the microorganisms.

The diagram shows the measles virus.

(These are not the real shapes or sizes of the pathogen or antigen!)

 

Which antibody - A, B or C - will match up with the measles' antigens?

 

Image of measles pathogen    Image of antigens

Fill in the blanks below to describe immunity. 

Define the key terms of the immune system.

Column A

Column B

Antigens
Molecules on the surface of cells and pathogens
Antibody
The ability to produce antibodies against a pathog...
White blood cell
White blood cells that stay in the blood after inf...
Immunity
Protein molecule made by white blood cell to fight...
Memory cell
Cells in the blood that are part of the immune sys...

Describe how antibodies function by putting these sentences in the order in which they occur. 

 123456
White blood cells make proteins called antibodies
Different antibodies bind to different antigens on different microorganisms
Phagocytes are white blood cells that digest the clumps of microorganisms and destroy them
Binding of antibodies to microorganisms makes them clump together
Microorganisms enter the body during infection
Antibodies recognise markers on the surface of the microorganisms called antigens and bind to them

X is found on the surface of a pathogen.

 

What is the name of X? 

 

Image of antigen and antibody

Describe how the white blood cell in the image is able to protect the body from disease 

 

 

image of white blood cell

The white blood cell produces antigens of the pathogen

The white blood cell is able to recognise antigens on the pathogens

The white blood cell engulfs, ingests and destroys the pathogen

The white blood cell kills the antibodies

How are phagocytes and lymphocytes different?

Lymphocytes recognise antigens on the surface of pathogens

Phagocytes and lymphocytes are both white blood cells

Phagocytes engulf and ingest pathogens

Phagocytes and lymphocytes both destroy pathogens

Toxins produced by pathogens can make us feel ill.

 

How do white blood cells respond to toxins? 

Lymphocytes produce antibodies which bind to the pathogen and neutralise it

Lymphocytes produce antitoxins which bind to the pathogen and neutralise it

Lymphocytes produce toxins which bind to the pathogen and neutralise it

The human body has many defences against invading pathogens.

 

Place the defences into the correct column below.

 Physical defenceChemical defence
Hydrochloric acid in the stomach
Ciliated cells in airways
Mucus produced by goblet cells in lungs and airways
Lysozyme in eyes and mouth
Skin covering the body
Nose hairs

Emma has chickenpox. She doesn't mind though as she gets to miss school for a few days!

After Emma has been infected with the chickenpox virus, some of the white blood cells that made antibodies against it stay in her blood.

 

What are these cells called that stay in Emma's blood?

Antibodies

Memory cells

Red blood cells

  • Question 1

White blood cells make antibodies with shapes that fit the antigens. Other white blood cells can then find and destroy the microorganisms.

The diagram shows the measles virus.

(These are not the real shapes or sizes of the pathogen or antigen!)

 

Which antibody - A, B or C - will match up with the measles' antigens?

 

Image of measles pathogen    Image of antigens

CORRECT ANSWER
A
EDDIE SAYS
How are your jigsaw puzzle skills? A will fit the measles' antigen, just like a puzzle!
  • Question 2

Fill in the blanks below to describe immunity. 

CORRECT ANSWER
EDDIE SAYS
Immunity is all about how memory cells help to protect us from getting ill in the future! This is how vaccinations work. If we have had a vaccination against a disease, memory cells in our bodies have learned how to deal with the disease and can respond quickly if they meet it again.
  • Question 3

Define the key terms of the immune system.

CORRECT ANSWER

Column A

Column B

Antigens
Molecules on the surface of cells...
Antibody
Protein molecule made by white bl...
White blood cell
Cells in the blood that are part ...
Immunity
The ability to produce antibodies...
Memory cell
White blood cells that stay in th...
EDDIE SAYS
This is a good activity to consolidate your knowledge. To help with your revision, have a few tries!
  • Question 4

Describe how antibodies function by putting these sentences in the order in which they occur. 

CORRECT ANSWER
 123456
White blood cells make proteins called antibodies
Different antibodies bind to different antigens on different microorganisms
Phagocytes are white blood cells that digest the clumps of microorganisms and destroy them
Binding of antibodies to microorganisms makes them clump together
Microorganisms enter the body during infection
Antibodies recognise markers on the surface of the microorganisms called antigens and bind to them
EDDIE SAYS
How did you do? Don't worry if you didn't manage it the first time around - practice makes progress!
  • Question 5

X is found on the surface of a pathogen.

 

What is the name of X? 

 

Image of antigen and antibody

CORRECT ANSWER
antigen
EDDIE SAYS
Some similar words here, so make sure you know which is which! Antibodies, produced by white blood cells, fit antigens rather like a puzzle piece. This means that the pathogens will clump together, and it will be easier for phagocytes to engulf and destroy them.
  • Question 6

Describe how the white blood cell in the image is able to protect the body from disease 

 

 

image of white blood cell

CORRECT ANSWER
The white blood cell is able to recognise antigens on the pathogens
The white blood cell engulfs, ingests and destroys the pathogen
EDDIE SAYS
Several similar looking options here, so you need to take it slowly and read the choices carefully. The white blood cell in the picture is a phagocyte and the process of engulfing, ingesting and destroying a pathogen is called phagocytosis. The white blood cell recognises the pathogen because an antibody has locked on to its antigen. The white blood cell (the phagocyte) now surrounds the pathogen, engulfs it and ultimately, destroys it!
  • Question 7

How are phagocytes and lymphocytes different?

CORRECT ANSWER
Lymphocytes recognise antigens on the surface of pathogens
Phagocytes engulf and ingest pathogens
EDDIE SAYS
All four of the options above are true, but two of them are about their similarities. They are alike in that they are both white blood cells that destroy pathogens. The other two options outline their differences. Phagocytes are non-specific white blood cells that engulf and ingest pathogens. Lymphocytes, however, can be said to be specific, producing specific antibodies to lock on to the antigens of a pathogen.
  • Question 8

Toxins produced by pathogens can make us feel ill.

 

How do white blood cells respond to toxins? 

CORRECT ANSWER
Lymphocytes produce antitoxins which bind to the pathogen and neutralise it
EDDIE SAYS
You need to read the three options very carefully here! Lymphocytes do indeed produce antibodies, but these lock on to antigens on pathogens - they don't neutralise toxins. Toxins are neutralised by antitoxins produced by lymphocytes. That's another activity completed!
  • Question 9

The human body has many defences against invading pathogens.

 

Place the defences into the correct column below.

CORRECT ANSWER
 Physical defenceChemical defence
Hydrochloric acid in the stomach
Ciliated cells in airways
Mucus produced by goblet cells in lungs and airways
Lysozyme in eyes and mouth
Skin covering the body
Nose hairs
EDDIE SAYS
This would be a good task for revision or for an extended response in an exam question as it allows you to compare both easily. Did you manage to sort them into their correct columns? The key to remembering which is which is that physical defences are to do with an actual physical barrier, whereas chemical defences need to be produced by the body in the form of acid or enzymes.
  • Question 10

Emma has chickenpox. She doesn't mind though as she gets to miss school for a few days!

After Emma has been infected with the chickenpox virus, some of the white blood cells that made antibodies against it stay in her blood.

 

What are these cells called that stay in Emma's blood?

CORRECT ANSWER
Memory cells
EDDIE SAYS
How did you do? Antibodies are produced by white blood cells to help to destroy pathogens in the body, but it is the memory cells that help her body to recognise the chickenpox pathogen should she develop the disease again. Memory cells form a vital part of our immune systems. They help to protect us if we get infected by a pathogen a second time.
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