The Immune System Flashcards
What does the immune system do?
helps to protect the body from disease and infection by attacking pathogens if they manage to enter the body
What are lymphocytes?
white blood cells
they are part of the immune system
Describe how the immune system attacks a pathogen
A pathogen enters the blood.
Pathogens have unique antigens on their surface.
The pathogen bumps into lymphocytes until it meets one with a complementary shaped antibody.
The lymphocyte will only activate if the pathogens antigen fits into its antibody.
Once a lymphocyte is activated it starts to divide and produces identical clones of itself.
Some of the lymphocytes produce lots of antibodies which stick to the pathogens and destroy it.
The pathogens can’t enter cells if they are stuck together by antibodies.
A phagocyte then crushes the pathogens, killing them.
Some lymphocytes remain in the blood as memory lymphocytes.
If the pathogen returns, the memory lymphocytes will respond quicker/immediately and produce more antibodies.
What is on the outside of lymphocytes and what do they do?
antibodies
they are specific to one kind of pathogen
they stick to pathogens and cause them to clump together
What is on the outside of a pathogen?
antigens
they are unique for each type of pathogen
What is a pathogen?
an organism that causes an (infectious) disease
What is the secondary response?
If the same pathogen enters the body again, the immune system will produce a quicker, stronger (more antibodies) immune response
This is because the memory lymphocytes are still in the blood.
Explain why there is a delay of a few days between a person becoming infected by a pathogen for the first time and antibodies being made.
It takes time for lymphocytes to identify the antigens on the pathogen, and to produce specific antibodies
Pathogens have antigens that are foreign to the body. When a pathogen enters the body, the body is exposed to those antigens.
Describe two responses triggered by the antigens.
The antigens trigger an immune response which causes the production of antibodies.
They also trigger the production of memory lymphocytes.
Describe how the immune system helps to fight infection.
the pathogen has a unique antigen on its surface
a lymphocyte with an antibody that fits the antigen is activated
this lymphocyte divides rapidly
the lymphocyte produces antibodies that destroy the pathogen
