Chapter 21.4 - 21.6 - adaptive immune system Flashcards
What are antigens?
Substances that can mobilize adaptive defenses and provoke an immune response
What are two important functional properties complete antigens?
Immunogenicity: ability to stimulate proliferation of specific lymphocytes
reactivity: ability to react with activated lymphocytes and antibodies released by immunogenic reactions
What are incomplete antigens?
also called haptens, involve molecules too small to be seen so are not immunogenic by themselves
When becomes a hapten immunogenic?
If hapten attaches to body’s own proteins
What are antigenic determinants?
Certain parts of an entire antigen that are immunogenic
What binds to atigenic determinants?
Antibodies and lymphocytes
What are self-antigens?
All cells are covered with variety of proteins located on surface that are not atigentic to seld, but may be antigenic to others in transfusions or grafts
What is an important group of self-proteins?
MHC proteins
What does a MHC protein contain?
A groove that can hold piece of self-antigen or foreign antigen
When can T lymphocytes recognize antigens?
When they are presented on MHC proteins
Where are class I MHC proteins found?
All body cells
Where are class II MHC proteins found?
Cells in the immune response
Which helps mobilize adaptive defenses?
In infected cells MHC proteins display fragments of foreign antigens
What are three crucial types of cells in the adaptive immune system?
B and T lymphocytes and Antigen-presenting cells
Where do B cells mature?
The red bone marrow
Where do T cells mature
In the thymus
What is immunocompetence?
They are able to recognize and bind to a specific atigen
To where are naive B and T cells exported
Lymph nodes, spleen and other lymphoid organs
What are major types of APCs?
Dendritic cells, macrophages and B cells
How do dendritic cells work?
Phagocytize pathogens that enter tissues, then enter lymphatics to present antigens to t cells in lymph node
How do macrophages work?
Present antigens to T cells which not only activates T cell, but also further activates macrophages
How do B lymphocytes work?
Present antigens to helper T cell to assist their own activation
When is the humoral immune response provoked?
When B cell encounters target antigen, antibodies specific for that particular antigen are then produced
When are B cells activated?
When antigens bind to surface receptors, cross-linking them
What is the function of memory cells
Provide immunological memory
Mount an immediate response to future exposures to same antigen
