Topic 2 - Cell Recognition And The Immune System Flashcards
(18 cards)
What is cell recognition?
Vital process in the immune system that allows the body to distinguish between self and non-self substances. This is essential for protecting the body against infection and ensuring the immune system does not attack healthy cells.
What is an antigen?
An antigen is a protein on the surface of a cell or virus that triggers an immune response.
What is four things are antigens able to identify?
- self cells
- non-self cells
- Abnormal cells
- toxins
What are T cells?
Recognise antigens presented on the surface of infected or abnormal cells. They trigger an immune response including the destruction of infected cells.
What are B cells?
Find two specific antigens using antibodies and produce antibodies to neutralise pathogens.
What is the process of cell recognition?
- Detection of foreign antigens. Lymphocytes patrol the body and examine the antigens on the surface of cells. They detect they are non-self and initiate an immune response.
- Clinal selection: specific lymphocytes that recognise the foreign antigens are activated and divide rapidly.
- destruction of non-self cells:cytotoxic\ T cells destroy infected cells or antibodies.
What are self antigens?
Found on the surface of the bodies, own cells identified as normal by the immune system preventing an immune response.
What are non-self antigens?
Found on pathogens, abnormal cells or foreign substances and trigger an immune response.
What is phagocytosis?
The non-specific immune response where phagocytes engulf and destroy pathogens.
What are the steps of phagocytosis?
- Detection and binding: phagocytes detect pathogens by recognising their antigens, they bind to the pathogen using receptors on its cell surface membrane.
- The phagocytes extends in its cytoplasm surrounding the pathogen and forming a phagocytic vacuole.
- The lysosome in the vesicle fuses with the vacuole and forms a phagolysosome.
- The enzyme lysozyme hydrolyses the pathogen.
- Antigen presentation
What is antigen presentation?
Fragments of the pathogen, including its antigens are transported to the surface of the phagocyte, then becomes an antigen presenting cell displaying the pathogen antigens to other immune cells.
What is a macrophage?
Large phagocytes that reside in tissues and are long lift and act as antigen presenting cells to activate T cells.
Where to T cells develop and mature?
They are produced in the bone marrow, but they might grate to the thymus gland where they mature and differentiate.
What is cell mediated immunity?
- T cells respond to antigen presenting cells displaying non-self antigens on their surface.
- This is crucial for fighting intracellular pathogens and abnormal cells.
Stages of cell mediated response
- T cells binds to APCs, due to its complimentary receptors.
- The T cell becomes activated
- The activated T cell divide by mitosis producing many identical T cells specific to the antigen.
- They differentiate into different types of. T cells helper T cells cytotoxicity cells and memory T cells
What are helper T cells?
Release cytokines to stimulate B cells cytosine T cells and phagocytes.
What are cytotoxic T cells?
Kill infected or abnormal cells by releasing perforins which create pools in the target cell membrane causing death.
What are memory T cells?
Persisted after the infection to provide a faster stronger response to the same antigen is encountered again.
