Immune response Flashcards
What are the four stages of the immune response?
Phagocytosis
T-Cells
B-Cells
Antibody production
What is a phagocyte?
A type of white blood cell
What is phagocytosis?
The engulfment of pathogens
What is the first stage of phagocytosis?
The phagocyte recognises the foreign antigens on a pathogen
What is the second stage of phagocytosis?
The cytoplasm moves around the pathogen to engulf it, containing it in a phagocytic vacuole
What is the third stage of phagocytosis?
A lysosome, which contains lysozyme enzymes, breaks down the bacteria after it fuses with the phagocytic vacuole
What does a phagocyte become?
Antigen presenting cell
What is a T-Cell?
A type of white blood cell
What do t-cells have on their surface and what do they do?
Receptor proteins which bind to complimentary antigens presented to it by phagocytes
What are the two types of T cells?
Helper T-cells
Cytotoxic T-cells
What do helper T-cells do?
Release chemical signals that activate and stimulate phagocytes
What do cytotoxic T-cells do?
Kill abnormal and foreign cells
Activate B-Cells
What are B-cells?
A type of white blood cell
What are B-cells covered in?
Antibodies
What are antibodies?
Proteins that bind to antigens to form an antigen-antibody complex
What happens when an antibody on the surface of a B-cell meets a complimentary shaped antigen?
It binds to it
What activates B-cells? What is this called?
The formation of an antibody-antigen complex and the chemicals released from the T-cells
Clonal selection
What does the activated B-cell divide into?
Plasma cells
What are plasma cells identical to?
B-cells
What are monoclonal antibodies?
The antibodies which plasma cells secrete loads of which are specific to the antigen
What is formed when an antibody binds to an antigen?
Antibody-antigen complex
What is agglutination? How does this happen?
Pathogens becoming clumped together
The antibody has two binding sites so two pathogens can bind at the same time
What is the same in all antibodies?
Constant region
What is different in all antibodies?
Variable region
How is one antibody specific to just one antigen?
The variable region has a unique tertiary structure, due to different amino acid structures
What forms the cellular response?
The T-cells and other immume system cells they interact with
What forms the humoral response?
B-cells, clonal selection and the production of monoclonal antibodies
What is the primary response?
When an antigen enters the body for the first time, activating the immune system
Is the primary response fast or slow? Why?
Slow
There aren’t many B-cells that can make the antibody needed to bind to it
What do T-cells and B-cells produce after being exposed to the antigen?
Memory cells
What do memory T-cells do during the primary response?
Remember the specific antigen and will recognise it a second time round
What do memory B-cells do during the primary response?
Record the specific antibodies needed to bind to the antigen
What is the secondary response?
When the same pathogen enters the body again and the immune system produces a quicker and stronger immune response
Is the secondary response fast or slow? Why?
Fast
Clonal selection happens faster
What do memory B-cells do during the secondary response?
They are activated and divide into plasma cells which produce the right antibody for the antigen
What do memory T-cells do during the secondary response?
They are activated and divide into the correct type of T-cells to kill the cell carrying the antigen
Explain why antibodies are only effective against a specific pathogen. (2 marks)
1) their binding sites are complimentary to the antigen
2) they can bind to form an antigen-antibody complex
Why might babies already have measles antibodies before their MMR vaccination? (application)
They have received maternal antibodies from their mother