Chapter 17: Types of Immunity and Immunology Flashcards
Immunity
The ability of an organism to recognize and defend itself against an infectious agent
Susceptibility
The opposite of immunity. Being vulnerable to harm by infectious agent
Immunology
The study of adaptive immunity and how the immune system responds to the specific infectious agents and toxins
Adaptive/Acquired immunity
The ability of a host to mount a defense against a particular infectious agent by physiological responses specific to that infectious agent, not hereditary immunity
Naturally Acquired immunity
(1) Most often obtained by having a specific disease (2) Immune system responds to molecules called antigens and invading infectious agents (3) Activates T cells and produces molecules called antibodies
Example of Naturally acquired
Antibodies transferred from mother to fetus through placenta
Artificially acquired Immunity
Obtained by receiving an antigen by the injection of vaccine or immune serum that produces immunity
Active immunity
Created when the persons own immune system activates T cells or produces antibodies or other defenses against an infectious agent (antibodies can last a lifetime or just a few weeks/months)
Active Natural Immunity
Exposure to infectious agent; is produced when a person is exposed to an infectious agent
Active Artificial Immunity
Immunization; produced when a person is exposed to a vaccine containing, live, weakened or dead organisms or their toxins. Body’s immune system remembers the antigen to which it has responded from
Passive immunity
Created when ready-made antibodies are introduced into the body, passive because the host does not have to make antibodies
Passive Natural Immunity
Maternal antibodies; is produced when antibodies made b other hosts are introduced into a new host
Passive Artificial Immunity
Antibodies from other sources are injected (Being injected with antivenin injection after being bitten by poisonous snake)
Antigen
A substance the body identifies as foreign and toward which it mounts an immune response to or an “immunogen”
What are antigens made of?
(1) Large complex protein molecules (2) Some are polysaccharides, some are glycoproteins and some are nucleoproteins
Why are proteins used to make antigens?
Proteins have a greater antigenic strength because they are more complex
Epitopes or antigenic determinants
Area on the molecule to which antibodies can bind
Polyclonal antibodies
Different antibodies that all recognize different epitopes on a specific microorganism
What determines the chemical structure of a cells antigen?
Genetic info
Do microorganisms have one or more antigens on their surface?
Can have multiple on their surface
Importance in making a vaccine
Determining how the body is going to react to different antigenic determinants
Hapten
Small molecule that can act as an antigen if it binds to a larger protein molecule, can act as epitopes on surface of proteins
Antibody
(1) A protein produced in response to an antigen that is capable of binding specifically to the foreign antigen (2) Each antigen binds to a specific antigenic determinant and may inactivate an antigen
Titers
(1) The quantity of a substance present in a specific volume of body fluid (2) Increases during infection (3) Serves as an indication of an immune response by the body
Antibody titer
Quantity of antibody needed to bind to and neutralize a particular quantity of an antigen
Where do lymphocytes develop from?
Stem cells
Where are lymphocytes processed and matures in? What do they mature into?
Lymphoblasts are processed and matured in tissue and become lymphocytes both B and T, then the B matures in bone marrow, T matures in the Thymus and then they both go to the lymph once they are done
Where does B cell differentiation take place?
In the bone marrow
Where are B cells found?
Lymph Tissue and GALT (Lymphoid digestive tract), Peyers patches
What type of acquired immunity are B cells found in?
Humoral immunity
What do B cells secrete?
Antibodies that react with particular antigens
Where do T lymphocytes undergo differentiation?
Thymus
Where are T cells found
Same places as B cells, Thymus, Lymph tissue and GALT
What type of acquired immunity are T cells found in?
Cell mediated immunity
What are the 4 types of cells that T cells produce? And what do they do?
(1) Cytotoxic T cells: directly interact with bad cells (2) Delayed hypersensitivity T cells: help macrophages and stimulate the macrophage to destroy pathogen (3) Helper T cells: Help B cells make antibodies (4) Regulatory T cells: Regulate immune system
After differentiation where do T cells go?
Migrate along lymph tissue and blood
Natural Killer cells (NK)
Nonspecifically kill cancer cells and cells infected with viruses without utilizing specific immune responses
What do NK cells release and do?
(1) They release various cytotoxic molecules that perforate membranes leading to lysis (2) Other molecules enter through pores and fragments its DNA causing apoptosis (3) NK cells are then infected by interferons
Apoptosis
Programmed cell death
What are the 2 types of immunity lymphocytes give rise to?
Humoral immunity and Cell-mediated immunity
Humoral immunity
Is carries out by antibodies circulating in blood
What is the process of Humoral immunity?
(1) When stimulated by antigen, B cells initiate a process that leads to release of antibodies (2) Done before cells enter a cell
Cell mediated Immunity
Carried out by T cells within a cell (involve differentiation and activation of several kinds of T cells and the secretion of cytokines, NO B cells)
What is the process of Cell mediated immunity?
(1) Processed antigens on MHCII molecule bind to T receptor (2) IL-1 secreted from macrophages and IL-2 secreted from T cells activate T cells which differentiate into TH1 and TH2 (3) TH1 releases interferon, a cytokine that causes infected amcrophages to become resensitized to cytokines (4) Most effective in clearing the body of virus infected cells but also participates in defending against fungi and helminths, cancer and foreign tissue
Properties of Immune Response
(1) Recognition of Self vs Non-self (2) Specificity (3) Heterogeneity (4) Memory
Clonal selection hypothesis
(1) Explains that embryos containing many different lymphocytes, each genetically programmed to recognize a particular antigen, make antibodies to destroy it (2) Next, if lymphocyte recognizes that antigen after development is complete it divides to produce clones and then a group of identical progeny (3) However, if during development the lymphocyte encounters its programmed antigen (meaning its targeting itself) the lymphocyte is destroyed (When b cell recognizes specific epitope on antigen, it binds to antigen, engulfs, presents fragment as MHCII to TH2 cells and divides then B cells differentiate into memory or plasma cells)
Tolerance regarding clonal deletion theory
(1) Immune system destroys the lymphocyte that targets self before they can make more copies once development is over (2) Can be acquired through organ transplants with the help of an immunosuppressant
Cross reactions regarding immunity
Reactions of a particular antibody with very similar antigens, resulting in either an antigen for multiple strains of a similar infection of antibodies made that destroy both host cells and antigen cells (can be good or bad)
Importance of heterogeneity in immune response
(1) Ability to make a variety of different antigens if a bacterium or foreign agent has more than one kind of antigenic determinant (2) Producing different antibodies for different kinds of epitopes
Importance of Memory in immune response
Stand ready for years or decades to quickly initiate antibody production
Anamnestic response
Secondary quick response due to the ability to recall seeing the antigen before
Where do B cells carry their antibody?
On its membrane so it can bind immediately
What does binding of an antigen do?
It sensitizes or activates B cells causing it to divide