IELTS LISTENING – Immunity and Immunization S39T4


Immunity and Immunization

Lecturer :

Good afternoon, and thank you for your warm welcome. This will be the first talk in a series of five on health interventions, protection, and prevention. Could I start by asking for a show of hands? How many of you have had a flu vaccination at the beginning of winter? Ah, I thought so. You young ones always think you’re indestructible. Well, as you’ve no doubt aware, disease-spreading germs or pathogens are everywhere.

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On a daily basis, the human body has to ward off attacks by various harmful bacteria and viruses. A healthy body has a good defence system against many of these germs. But the defence only operates well against microorganisms that it has already encountered, in which case it is said to be immune.

There are two ways in which humans acquire natural immunity. Actively, when a person has first suffered and then recovered from an illness and passively when ready-made protection is transferred into the body, for example, from the maternal blood fire the umbilical cord to an unborn child or through breast milk. Now artificially acquired immunity can help the body to fight disease so we can use active immunization as a preventative measure. This is when a person is vaccinated against illness by injection or oral ingestion of a tiny amount of weakened or inactive germs not enough to actually cause him or her to contract the illness, but sufficient for the body’s defence system to recognize and respond to the threat by forming antibodies. Intervention using passive immunization, on the other hand, is a method of curing an illness after it is too late for prevention. It is less effective than active immunization and takes longer to work. It is used when the body has already been invaded by bacteria and the person is ill. In this case, there is no time for the body to make antibodies of its own. So proteins, usually taken from the blood of animals are injected to equip the patient with the essential antibodies to combat the particular illness. Let’s have a quick look at a bit of history. The discovery of vaccination to boost the body’s immune system by making it sensitive to particular disease-causing bacteria was made by an 18th-century English doctor cooled Edward Jenna.

He noticed that survivors of smallpox, a common but extremely dangerous disease, never contracted the disease a second time. In other words, they were immune. He studied a similar disease in cows called cowpox and realized that people in contact with the infected cows became ill with symptoms resembling smallpox. However, this disease was quite mild by comparison and those who contracted cowpox were then immune to smallpox.

He conducted an experiment by injecting a child with a small amount of pass taken from a cowpox postural. The child subsequently became ill, but soon recovered. Later, he injected the child with Puss from smallpox postural, and the child did not get sick. He had developed immunity to the more dangerous disease. The antibodies produced to fight the cowpox bacteria had been able to fight off the smallpox bacteria.

What are antibodies? Well, antibodies are made by white blood cells called B lymphocytes, and this is done in response to the presence of antigens or other bacterial toxins which have been released by the microorganisms. What we commonly refer to as germs that have invaded the body. These Y shaped antibodies. Or you can think of them as antitoxins may stop the toxins or repair the damage they have done by what is known as the antigen-antibody reaction, which takes place within the plasma of the blood. The correct antibody for that disease clings to a particular Auntie Jen. In order to render it harmless.

large numbers of these pears clumped together to form a bigger unit. This is called a hallucination and is able to be seen by the naked eye, which is very helpful for doctors and other specialists to determine which illnesses a patient is immune to. Inoculation or active vaccination can protect people from serious diseases.

The vaccine may make a person feel unwell for a few days when the immune system starts to produce antibodies to match the introduced Auntie Jen. This is called a primary reaction. If that particular Auntie Jen should ever enter the body again later, a secondary reaction takes place. The body is then able to produce large numbers of corresponding enter bodies within a short time, so the invading antigen are quickly wiped out without the person suffering any harm from the disease.

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