Cells and the immune system Flashcards
What are antigens?
molecules that can generate an immune response when detected by the body
What do antigens allow the body to identify?
pathogens, abnormal body cells, toxins and cells from other individuals of the same species
Describe the steps of phagocytosis.
- A phagocyte recognises foreign antigens on a pathogen.
- Cytoplasm of the phagocyte moves round the pathogen, engulfing it.
- Pathogen is now contained in a phagocytic vacuole in the cytoplasm of the phagocyte.
- A lysosome fuses with the vacuole and lysozymes are released and break down the pathogen.
- Phagocyte presents the pathogens antigens and acts as an antigen-presenting cell.
Describe the role of T-cells during immune response.
-white blood cell
-receptor cells that are complementary to antigens presented by the phagocytes
-helper T-cells release chemical signals that activate and stimulate phagocytes, they also activate B-cells
-cytotoxic T-cells kill abnormal and foreign cells
Describe the role of B-cells during immune response.
-white blood cell
-covered with antibodies, which bind to antigens to form an antigen-antibody complex
-the antibodies have a specific shape and only bind to antigens that they are complementary to
-when the B-cell is activated it divides into plasma cells which are identical to the B-cells
Describe what happens during antibody production during immune response.
-Plasma cells release loads of antibodies which are specific to the antigen, these are called monoclonal antibodies
-antibodies have two binding sites so can bind to two pathogens so they become clumped together, this is called agglutination
What are antibodies made up of?
chains of amino acids, variable regions
What is cellular response?
T-cells and other immune system cells that they interact with
Give an example of cellular response.
Phagocytes
What is humoral response?
B-cells, clonal selection and the production of monoclonal antibodies
What is primary response?
-When an antibody enters the body for the first time
-slow because there aren’t many B-cells that make the antibody
What are memory cells and how are they produced?
-produced by B-cells and T-cells
-they remember a specific antigen and recognise it at second infection
-cause immunity to diseases
What is secondary response?
-same pathogens infects body
-much quicker and stronger immune response
-Often gets rid of pathogen before you show symptoms
What is active immunity?
when your immune system makes its own antibodies after being stimulated by an antigen
What is natural active immunity?
when you become immune after catching a disease
What is artificial active immunity?
when you become immune after you’ve been given a vaccination containing a harmless dose of antigen