Immunology Flashcards
What is immunology?
the study of the structure and function of the immune system
What is the Immune system?
Cells, tissues, and molecules that mediate resistance to infections
What is an Immune response?
collective and coordinated response to the introduction of foreign substances in an individual mediated by the cells and molecules of the immune system
What is immunity?
Resistance of a host to pathogens and their toxic effects
What is the role of the immune system?
Defense against microbes
Defense against the growth of tumor cells
Homeostasis
destruction of abnormal or dead cells
Which organs play a role in the immune system?
Tonsils and adenoids
Thymus
Lymph nodes
Spleen
Peyer’s patches
Appendix
Lymphatic vessels
Bone marrow
Which cells play a role in the immune system?
Lymphocytes
T-lymphocytes
B-Lymphocytes, plasma cells
natural killer lymphocytes
Monocytes, Macrophage
Granulocytes
neutrophils
eosinophils
basophils
Which molecules play a role in the immune system?
Antibodies
Complement
Cytokines
Interleukines
Interferons
What are the 2 types of immunity?
Innate and acquired
What is innate immunity?
Non-adaptive
First line of immune response
Relies on mechanisms that exist before infection
What is acquired immunity?
Adaptive
A second line of response (if innate fails)
Relies on mechanisms that adapt after infection
Mediated by T- and B- lymphocytes
One cell determines one antigenic determinant (specificity)
What is innate immunity based on?
genetic make up
What does innate immunity rely on?
already formed components
How fast is the response in innate immunity?
Rapid - within minutes of infection
Is innate immunity specific, and does it have memory?
Not specific - same molecules / cells respond to a range of pathogens
Has no memory - same response after repeated exposure
What is acquired immunity based upon?
resistance acquired during life
What does acquired immunity rely on?
genetic events and cellular growth
How fast is the response in acquired immunity?
Responds more slowly, over few days
Is acquired immunity specific, and does it have memory?
Is specific - each cell responds to a single epitope on an antigen
Has anamnestic memory - repeated exposure leads to faster, stronger response
Which type of immunity leads to clonal expansion?
Adaptive or acquired
What are the 2 mechanisms within acquired/ adaptive immunity?
Cell-mediated immune response (CMIR)
Humoral immune response (HIR)
What is involed in Humoral immune response (HIR)?
B-lymphocytes
mediated by antibodies
eliminate extra-cellular microbes and their toxins
What is involved in Cell-mediated immune response (CMIR)?
T-lymphocytes
Eliminate intracellular microbes that survive within phagocytes or other infected cells
What do T- cells do within a cell-mediated immune response?
Recognizes peptide antigen on macrophage in association with major histo-compatibility complex (MHC) molecules
Identifies molecules on cell surfaces
helps body distinguish self from non-self
T-cells differentiate into effector cells that are capable to kill infected cells
What are the 2 types of T lymphocytes and what are their functions?
Helper T- lymphocytes (activates phagocytes to kill microbes)
Cytolytic T-lymphocyte (destroy infected cells containing microbes or microbial proteins)
What are the 3 stages of humoral immune response?
B lymphocytes recognize specific antigens.
They proliferate and differentiate into antibody-secreting plasma cells.
Antibodies bind to specific antigens on microbes; destroy microbes via specific mechanisms
Some B lymphocytes evolve into the resting state - memory cells
What are the 5 types of antibodies?
IgG, IgM, IgA, IgD, IgE
What are antibodies?
Belong to the gamma-globulin fraction of serum proteins
Y-shaped polypeptides
2 identical heavy chains
2 identical light chains
What is IgG responsible for?
70-75% of total immuniglobulin
Secreted in high quantities in secondary exposures
+ neutralize microbes and toxins
+ opsonize antigens for phagocytosis
+ activate the complement
+ protect the newborn - can cross the placenta
What is IgM responsible for?
What is IgG responsible for?
Secreted initially during primary infection
Cannot cross the placenta
+ secreted first during primary exposure
+ activates the complement
+ used as a marker of recent
infection
What is IgA responsible for?
Monomeric in serum
Dimeric with secretory component in the lumen of the gastro-intestinal tract and in the respiratory tract
+ neutralizes microbes and toxins
What is IgD responsible for?
Monomeric
+ present on the surface of B lymphocytes
+ functions as membrane receptor
+ role unclear - has a role in antigen stimulated lymphocyte differentiation
What is IgE responsible for?
Mediates type I hypersensitivity
Monomeric
+ associated with anaphylaxis
+ plays a role in immunity to helminthic parasites
Immune response helps individuals defend against what?
microbes and cancers
When does the immune response fail?
hypersensitivity reactions
immunodeficiency
What is Immunodeficiency?
+ Loss or inadequate function of various components of the immune system
+ Can occur in any part or state of the immune system
- physical barrier, phagocytes, B lymphocytes, T lymphocytes, complement, natural killer cells
+ The immuno-compromised host
has an impaired function of the immune system and is at high risk of infection
What are hypersensitivity reactions?
Hypersensitivity - overreaction to infectious/chemical agents
Allergy - overreaction to environmental/chemical substances
Autoimmunity - overreaction to self
Cause cell damage through excessive immune response to antigens
