Immune System & Defences
This lesson covers:
- The physical and chemical barriers that prevent pathogens from entering our bodies.
- The immune system, which destroys pathogens that do mange to enter our bodies.
The difference between antigens and antibodies.
An antigen is any substance that your body sees as foreign, which then causes your immune system to produce antibodies against it. For example, the toxins and cell walls of pathogens would be considered antigens.
An antibody on the other hand is a protein produced by our white blood cells that binds to specific antigens. This acts as a signal to our immune system to destroy the antigen (or the pathogen it is part of).
Which of the following act as barriers to reduce the entry of pathogens?
(Select all that apply)
Phagocytes
Skin
Hairs in the nose
Enzymes in tears
White blood cells
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How does skin help to defend against disease?
(Select all that apply)
It traps pathogens so that they can be removed
It covers the body, physically preventing pathogens from entering
It secretes oils and antimicrobial substances that kill pathogens
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Does skin act as a physical or chemical barrier to pathogens?
Physical barrier
Chemical barrier
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The nose has hairs inside it that act as a physical barrier to pathogens. What are the hairs in the nose coated with to catch pathogens?
Phagocytes
Mucus
Enzymes
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The cells that line the trachea, bronchi and bronchioles have tiny hair-like projections that waft the mucus and pathogens away from the lungs.
What are these structures called?
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What substance does the stomach produce to kill pathogens?
Hydrochloric acid
Enzymes
Nitric acid
Mucus
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Does the acid produced by the stomach act as a physical barrier, or a chemical barrier, to pathogens?
Physical barrier
Chemical barrier
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What is the role of the immune system?
The allow communication between different parts of the body
To regulate the level of water and ions in the blood
To locate and destroy pathogens that enter the body
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Which type of cells are part of the immune system?
White blood cells
Red blood cells
Nerve cells
Skin cells
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Phagocytes are a special type of white blood cell.
Which of the following are functions of white blood cells?
(Select all that apply)
Produce hormones
Producing antibodies
Phagocytosis
Produce antitoxins
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Stages of phagocytosis
cells / engulf / make / destroy / bind / phagocyte
- Phagocytosis is carried out by a special type of white blood cell called a .
- The first step is for the phagocyte to track down a pathogen, and then to it.
- The phagocyte's membrane will then surround the pathogen and it.
- Finally, enzymes inside the phagocyte break down the pathogen in order to it.
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What do antitoxins do?
Bind and neutralise the toxins produced by bacteria
Stimulate the immune system
Kill pathogens
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