Immune Respsonse Flashcards
What is a phagocyte?
a type of white blood cell that carries out an immune response known as phagocytosis.
Summarise phagocytosis in a phrase:
Engulfment of pathogens
Where are phagocytes found ?
In blood and in the tissues
Which cells are the first to respond if an immune response is triggered?
Phagocytes
How does a phagocyte work?
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How are T cells activated?
T cells are activated when the receptor proteins on their surface bind to complimentary antigens presented on phagocytes.
Name two types of T cell
T helper cell
T cytotoxic cell
T cells scan also be referred to as?
T lymphocytes
What do T helper cells do in the immune response?
T helper cells do not attack the foreign or abnormal cels himself instead they release chemical signals called cytokines . These chemical signals stimulate phagocytes and T cytotoxic cells into killing the abnormal or foreign cells. T helper cells also stimulate B cells.
If a T helper cell binds one of the receptor proteins on its surface to a complimentary antigen then what happens?
The T cell begins to replicate itself by mitosis to form many identical cells which carry the complimentary protein that binds to the invading antigen. The process is called clonal selection.
What do T cytotoxic cells do?
attack antigens on cell membrane of foreign pathogens; release cytotoxic substances that destroy pathogen
How are B cells stimulated ?
B cells can be stimulated by T helper cells as T helper cells release chemical signals to stimulate them. The binding of an antigen with a B cell receptor can also stimulate it into action.
What is the surface of B cells covered in?
Antibodies
What is formed when an antigen binds to an antibody?
an antigen-antibody complex
Do all B cells carry the same antibodies?
No each B cell has a different shaped antibody on its membrane so different ones bind to differently shaped antigens.
What happens when a B cell is activated?
When a B cell is activated it begins to divide into plasma cells , only the B cell which has complimentary antibodies to the antigens present begins to divide this is called clonal selection.
What do plasma cells do?
secrete antibodies (monoclonal)
What do the antibodies secreted by plasma cells do?
They bind to the antigens on the surface of the pathogen to form lots of antigen-antibody complexes
How many binding sites does a single antibody have?
two binding sites, so can bind to two pathogens at the same time
What process can occur due to the presence of two binding sites on a single antibody?
pathogens become clumped together — this is called agglutination. Phagocytes then bind to the antibodies and phagocytose many pathogens at once. This process leads to the destruction of pathogens carrying this antigen in the body.
What are antibodies and thus what are they made from?
Antibodies are proteins — they’re made
up of chains of amino acids.
What does the specificity of an antibody depend on?
The specificity of an antibody depends on its variable regions, which form the antigen binding sites. Each antibody has a variable region with a unique tertiary structure (due to different amino acid sequences) that’s complementary to one specific antigen
what is the part of the antibody that is generic in all antibodies referred to as?
constant regions
How are antibodies held together?
disulfide bonds
Name the two types of immune response?
Cellular and humoral
What is the cellular response?
the t-cells and other immune system cells that they interact with e.g phagocytes form the cellular response
What is the humoral response?
B-cells, clonal selection and the production of monoclonal antibodies
What is the primary response?
the immune response that results from the first exposure to an antigen
Why is the primary response slow?
there arent many B cells that can make the antibody needed to bind to the antigen
What do both T and B cells produce after being exposed to a antigen ?
Memory
In the secondary immune response , the immune system produces a quicker stronger immune response , why is this?
Clonal selection happens faster. Memory B-cells are activated and divide into plasma cells that produce the right antibody to the antigen. Memory T-cells are activated and divide into the correct type of T-cells to kill the cell carrying the antigen. The secondary response often gets rid of the pathogen before you begin to show any symptoms
