adaptive immunity and immunological memory Flashcards
third line of specific defence
- antigen specific
- systemic
- memory
antigen specific
the adaptive defence system recognizes and acts against particular foreign substances
systemic
immunity is not restricted to the initial infection site
memory
the adaptive defence system recognizes and mounts and stronger attack on previously encountered pathogen
what is humoral immunity?
antibody mediated immunity
what is cellular immunity?
cell mediated immunity
what are antigens?
human cells that are ‘self’ protein and carbohydrate molecules
examples of antigens
-nucleic acids
-some lipids
-pollen grains
-microorganisms
T cells and B cells become _
immunocompetent when the lymphocyte when it mature into a t cell or b cell
the lymphocytes surface determines
the capability to respond to a specific antigen by binding to it with antigen specific receptors that appear on the lymphocytes surface
where do T cells develop immunocompetence?
in the thymus and oversee cell-mediated immunity
where do B cells develop immunocompetence?
in bone marrow and provide humoral immunity
what do antigen-presenting cells do?
engulf antigens and then present fragments on their own surfaces to be regulated T cells
major types of APC:
-dendritic cells
-macrophages
-B lymphocytes
what do dentritic cells and macrophages do?
they present antigens to activate T cells that release chemicals to activate macrophages
what do b lymphocytes with specific receptors do?
they bind to specific antigen and are stimulated to continue their development
what does binding do?
sensitizes, or activates, the lymphocyte to undergo clonal selection
when does active immunity occur?
when b cells encounter antigens and produce antibodies
what can active immunity be?
-naturally acquired during bacterial and viral infections
-artificially acquired from vaccines
benefits of vaccines
-spare the signs and symptoms of the disease that would otherwise occur during the primary response
-weakened antigens still stimulate antibody production and promote immunological memory
-develops herd immunity without risks of the actual disease spreading
humoral immunity- active- naturally accquired
infection, contact with the pathogen
humoral immunity- active- artificially accquired
vaccine, dead or attenuated pathogens
humoral immunity- passive- naturally accquired
antibodies passed from mother to fetus via placenta, or to infant in her milk
humoral immunity- passive- artificially accquired
injection of donated antibodies (gamma globulin)
antibodies
soluble proteins secreted by activated B cells (plasma cells)
five major immunoglobulin classes (MADGE)
- igM
- igA
- igD
- igG
- igE
igM
found in blood, can fix complement
igA
found mainly in secretions, such as mucus, tears, breast milk
igD
important in activation of B cell
igG
can cross the placental barrier and fix complement, most abundant antibody in plasma
igE
found in mast cells just beneath epithelial surfaces, involved in allergies
what do immunocompetent t cells do?
they are activated to form a clone by binding with a recognized antigen
cytotoxic (killer) T cells- step 1
cytotoxic T cell binds tightly to the foreign target cell
cytotoxic (killer) T cells- step 2
cytotoxic T cell releases perforin and granzyme molecules from its granules by exocytosis
cytotoxic (killer) T cells- step 3
perforin molecules insert into the target cell membrane and form pores similar to those produced by complement activation
cytotoxic (killer) T cells- step 4
granzymes enter the target cell via the pores and degrade cellular contents
cytotoxic (killer) T cells- step 5
the cytotoxic T cell detaches and searches for another prey
what do regulatory t cells do?
-release chemicals to suppress the activity to t cells and b cells
-stop the immune response to prevent uncontrolled activity
-prevents reaction to self antigens
