Specific Immune Responce Flashcards
What is the specific immune response?
Antigen-specific involving T & B cells. It is aimed at specific pathogens
How is a T cell activated
Receptors on surface bind to complimentary antigens displayed by APCs
What will a T cell do once activated?
Divide by mitosis to produce clones of itself
What are the 3 types of T cell and what do they do?
- T helper cell: releases substances to activate B cells, T killer cells, and macrophages
- T killer cell: attach to antigens on infected cells and kills cell (along with pathogen)
- T memory cell
What 3 ways does interferon help prevent viruses spreading?
- Inhibit viral replication/ production of viral proteins
- Activate cells in specific immune response
- Promote inflammation
What cells activate B cells?
T helper cells
What are B cells covered in?
Proteins called antibodies
How is a B cell activated
1) When specific antibody binds to complementary antigen (forms antigen-antibody complex)
2) this together with substances released from T cell, activated B cell
What will an activated B cell do?
Divided by mitosis into:
1) plasma cells (b effector cells)
2) B memory cells
What cells make antibodies
Plasma cells (B effector cells), specific to 1 antigen
How are T and B lymphocytes functionally different
B lymphocytes secrete antibodies that bind to specific antigen that are NOT actually within body cells
T lymphocytes do not secrete antibodies. T cells bind to antigen on APC and destroy the body cell
Describe the role of plasma cells
- Secrete loads of antibodies into the blood
2. These antibodies will bind to antigens it surface of pathogen to form lots of antigen-antibody complexes
Deceive the structure of antibodies
- Four polypeptide chains- 2 heavy, 2 light
- Each chain has a variable region and a constant region
- Variable regions for antigen biding site, so shape is complementary to antigen
- Constant region allows binding to immune system cells so is same on all antibodies
- Disulphide bridges hold chains together
What three ways can antibodies help fight infection
- Agglutinating pathogens
- Neutralising toxins
- Preventing pathogen binding to human cells
Describe agglutinating pathogens
- Each antibody has 2 binding sites, can can bind to 2 pathogens at same time
- Pathogens then clump together
- Phagocyte then binds to antibodies and phagocytise a lot of pathogens at once
Describe neutralising toxins
Antibodies can bind to toxins that pathogens produce, preventing them from affecting human cells so toxins are neutralised
Describe how antigens prevent pathogen binding to human cells
Antibody blocks receptors used to bind to host cells, stopping pathogen attaching/ infecting host cells
What are the two types of antibodies
Membrane bound: attached to membrane of B cell
Can be secreted: not attached
What is the response when a pathogen enters the body for the first time?
Antigens activate non-specific response. In turn activating specific response
This makes up the primary response
Why is the primary response slow?
Aren’t many B cells that can make antibodies needed to bind to pathogen
What do T memory cells do?
Remember specific antigen
What do B memory cells do?
Remember specific antibodies needed to bind to pathogen
What does a second infection elicit
Secondary response
What are the 2 types of active immunity
- Natural: immunity after catching disease
2. Artificial: vaccine containing antigen
