Cells and the immune system Flashcards
What is the role of a phagocyte?
A type of white blood cell
Recognise foreign antigens
Engulfs the pathogen
Lysosome fuses and releases enzymes called lysozymes
The phagocyte presents the antigen to alert other cells
What is the role of a T-cell?
Type of white blood cell
Receptors bind to antigen on phagocyte
Helper T-cells release chemical signals
Cytotoxic T-cells kill abnormal and foreign cells
What is the role of a B-cell?
Type of white blood cell
Antibody of B-cell meets complementary antigen and binds
Activates clonal selection
B-cell divides into plasma cells
What is the role of plasma cells?
They secrete antibodies (monoclonal)
Bind to pathogen to form complexes
Antibodies can bind to two pathogens at the same time causing agglutination
Phagocytes then bind to antibodies and undergo phagocytosis (destroying the pathogen)
What is the cellular response?
T-cells and other immune cells they interact with
What is the humoral response?
B-cells, clonal selection and the production of monoclonal antibodies.
What is the primary immune response?
When an antigen first enters the body it activates the primary response Response is slow due to low B-cells Eventually more are produced Memory cells are produced Person is now immune
What is the secondary immune response?
The same pathogen enters the body
Clonal selection happens quicker
Memory cells are activated and divide into plasma cells
T-cells kill the antigen
Secondary response kills pathogen before symptoms occur
How do vaccinations works?
Contain dead, weakened antigens which cause the body to produce memory cells
The next time the body is exposed the secondary response occurs
How does antigenic variation
Antigens activate the primary response
When infected again the secondary response is activated
Some pathogens have changed surface antigens
So memory cells do not recognise them
The primary response occurs to fight the adapted pathogen
What is active immunity?
Natural, you become immune after having the disease
Artificial, immune after receiving a vaccination
The immune system makes its own antibodies
What is passive immunity?
Natural, a baby becomes immune by having antibodies passed from mothers breast milk
Artificial, become immune by being injected with antibodies
The immune system does not make its own antibodies
Explain how cancer treating drugs may work
Cancer cells have antigens called tumour markers
Monoclonal antibodies can be complementary to them
Anti-cancer drugs can attach to the antibodies
Therefore the cancer drugs can specifically target the cancer
Therefore less side effects are experienced
Describe how pregnancy testing works
Application area has antibodies bound to a coloured dye
When urine is applied, any hCG binds to the antibodies
The urine moves down the stick to the immobilised antibodies
When antibodies are present the blue headed complex sticks to the antibodies and shows a blue line
Describe how the ELISA test uses antibodies
Antigen is fixed to the bottom of the plate
Blood plasma sample is added
Any antibodies present will bind to the fixed antigens
Well is washed out
A secondary antibody with an enzyme is added
They bind to the antibody
A substrate is added and produces a coloured product when positive
