Immune System Flashcards
What does innate immunity do?
Recognizes traits shared by broad ranges of pathogens. Is a rapid response
Innate immunity: Barrier Defenses vs Internal defenses
Barrier: skin, mucous membranes, secretions
Internal: Phagocytic cells, natural killer cells, inflammatory response
What is adaptive immunity? (Vertebrates only!)
Recognition of traits specific to particular pathogens. A slower response
Adaptive immunity: Humoral response vs cell-mediated response
Humoral: Antibodies defend against infection in body fluids
Cell-mediated: Cytotoxic cells defend against infection in the body
Local vs Systemic inflammatory response
Local: skin looks red around wound
Systemic: whole body is inflamed (i.e. a fever)
What do mast cells release and what does that do?
Mast cells release histamines. Histamines trigger blood vessel dilation
What do macrophages release and what does that do?
Macrophages release cytokines. Cytokines are signaling molecules that recruit neutrophils (WBC).
What are the two types of phagocytic cells?
Macrophages (certain tissues), and neutrophils (bloodstream)
What do antimicrobial proteins (AMP’s) do?
They target pathogens, and usually induce a destructive consequence to the bacteria
What is pus?
Remnants of the ‘battleground’. Fluid rich in WBC’s, dead pathogens, and cell debris
What does a phagocytic cell do?
Engulfs (eats) pathogens
What does the lymphatic system do? (aka Adaptive immune system)
The vessels of the lymphatic system parallel blood vessels, and the lymphatic vessels will take interstitial fluid samples from different places in the body, to search for any pathogens. They circulate fluid called lymph, and bring lymph through lymph nodes.
What two types of lymphocytes does adaptive immunity rely on? (What responses do they each take care of?)
B-cells (humoral/antibody-mediated response) and T-cells (cell-mediated)
Describe B-cell receptors
Membrane-bound, two binding sites (looks like a Y)
Describe T-cell receptors
Membrane-bound, one binding site (straight up and down)
What are antigen receptors?
Receptors on B and T cells, each and every cell has a different type of antigen receptor. Millions of lymphocytes each with a different type of receptor.
What is the definition of antigen?
Any substance on or secreted by a pathogen that can elicit an immune response
What is clonal selection?
The proliferation of B-cells or T-cells that have the antigen receptor that matches the antigen
What happens once they find the B-cell that recognizes the antigen? What are the products called?
That B-cell then divides, and makes many copies of itself, called plasma B-cells, which produce antibodies!
What are memory B-cells?
Copies of the correct B-cell that are saved, so that the body can remember the antigen in the future.
What is neutralization and opsonization?
What antibodies do!
Neutralization - prevent infection by rendering the pathogen useless (surround it)
Opsonization - tag foreign bodies for phagocytosis
What is the first step of a T-cell?
They recognize antigen fragments that are presented by an infected host cell. Looks for intracellular pathogens.
(Infected cells and dendritic cells)
What are major histocompatibility complexes (MHC)’s?
They present antigen fragments on the surface of the infected host cell, to get T-cells to recognize the antigen. T-cells swap out till one is found with matching antibody.
What happens after the correct T-cell is found?
Helper T-cells, that can bind to the antigen, proliferate (multiply) - clonal selection
What else do helper T-cells do?
They signal cytotoxic T-cells to come and kill the infected host - to stop replication of the pathogen inside the host cell.
Also memory T-cells are created
4 major characteristics of why adaptive immunity is so powerful
1) Diversity of antigen receptors
2) Self-tolerance (will not bind to ourself)
3) B and T cell proliferation after activation
4) Immunological memory - easier to fight off infection that you’ve had in the past, cause your immune system remembers!
How is there so much diversity in antigen receptors?
Only a few genes code for them! But gene rearrangement (splicing out parts of DNA) can code for all kinds of combinations of receptors
What is a vaccine?
A non pathogenic form of a microbe or part of a microbe that elicits an immune response and immunological memory
4 cases when the immune response does not work
1) Immun rejection (organ transplants)
2) Exaggerated response (allergies)
3) Self-directed response (autoimmune conditions)
4) Diminished response (stress, lack of sleep, viral latency)
What is a dendritic cell?
A phagocytic cell that consumes a pathogen and then presents is antigen on the surface of its membrane
