Chapter 3 - Immune System Flashcards
What is an antigen?
Antigens are structures that sit on the surface of pathogens, and are recognisable by white blood cells (the immune system cells).
What do white blood cells carry on their surface?
Antibodies. Different white blood cells have different antibodies. Antibodies have specific shapes that match the corresponding antigens.
How do antibodies destroy pathogens?
By attaching to the antigen that matches its shape.
What happens to the white blood cell that identifies a pathogen?
It clones itself many times so that there are many cells fighting the infection.
What do the white blood cells do after the infection has been cleared?
Some of them remain in circulation as memory cells. They will recognise the same pathogen and respond more quickly in the event of reinfection— before the host feels ill.
What is immunisation?
Immunisation is vaccinating against a particular pathogen to immunise against disease prior to infection.
How are vaccines made?
Some are made with dead or weakened microbes, and some are made with pieces of antigens.
How do vaccines work?
The vaccine triggers the immune system without making the person ill, and subsequent memory lymphocytes, meaning that the individual is protected against secondary infection.
What is herd immunity?
People who cannot be vaccinated rely on the rest of society to protect them from diseases. If a population is majority immune, a pathogen cannot spread. This provides immunosuppressed and unvaccinated individuals with protection due to the unlikelihood of them encountering the pathogen.
What barriers do plants have to protect themselves from infection?
Physical barriers such as a waxy layer on their leaves called the cuticle, a cell wall, and woody plants have a layer of bark to protect them.
Chemical barriers such as digitalis, artemisinin, and salicylic acid.
Why are young plants more susceptible to infection?
The cuticle and cell wall is weaker, and easier to penetrate.
