Contains the full lesson along with a supporting toolkit, including teachers’ notes.
Allergy means ‘altered reaction’ – it is the inappropriate and harmful response of the body’s defence mechanisms to substances that are normally harmless. It can be an attack of sneezing and runny eyes (hay fever), an itchy red rash (eczema), wheezing when breathing (asthma) or swelling of lips and tongue and vomiting (food allergy). Allergies affect about a third of the population.
What is the inflammatory response?
Our immune system protects us against disease. If we get a cut it may become red and swollen. This inflammatory response is part of our general defence system. The tissues that are exposed to the environment (skin, gut lining, mouth, nose and lungs) have special cells, called mast cells, which release chemicals, including histamines, when the tissues are damaged. These substances cause the walls of blood capillaries to become more porous and white blood cells and blood proteins, which are needed for clotting and sealing wounds, can move out of the blood. Within an hour the area is teeming with white blood cells (monocytes, also called phagocytes), which engulf any foreign particles and clear the area for repair.
What is induced immunity?
The specific immune system or adaptive immune system, is specific to vertebrates, and is particularly effective against dangers to which we have previously been exposed. It consists of white blood cells called lymphocytes, of which there are two main types – B cells and T cells. They are both made in bone marrow but B lymphocytes mature in bone marrow and T lymphocytes mature in the thymus gland. Antigens are foreign molecules often on the surface of bacteria or viruses that trigger the immune response of the lymphocytes.