Immune System Flashcards
Immune System
functional system, not an organ sys.
-prevent disease causing agents from infecting us by getting into the body.
Two Components of the Immune Sys.
- Innate
- Adaptive
Innate immunity is_________
nonspecific
Adaptive immunity is________
specific
Pathogen
disease-causing microorganisms
Antigen
-the body doesn’t distinguish a diseased antigen from a non diseased one.
Nonspecific immunity
- always prepared
- attacks anything and everything foreign
Innate Immune Sys
- intact skin and mucosae
- phagocytes
- NK cells
- inflammation
- antimicrobial proteins
- fever
when skin barriers are breached it leads to________
inflammation
Specific immunity
- specific and adaptive
- uses B & T lymphocytes
- goes after specific pathogens
The first line of defense consists of______
the surface barriers:
- INTACT skin and MUCOSAE
when the first line of defense is penetrated, the second line of defense comes into play; the second line of defense consists of__________
internal defenses:
-phagocytes; NK cells; inflammation; antimicrobial proteins; fever
the hallmark of the second line of defense is ______
inflammation
the third line of defense is the _______
adaptive immune sys.
broken skin equals a______
point of entry
mucous membranes line and_____
“trap”
-functions with acidity to produce an harsh acidic environment
TWO types of macrophages:
- Free
- Fixed
Free macrophages______
wander in tissue spaces in search of cellular debris or “foreign invaders”
Fixed macrophages_______
ex: such as stellate macrophages in the liver are permanent residents of particular organs
superficial nonspecific immunity have______
enzymes that breaks things apart; more specific lysozymes that destroy bacteria
internal nonspecific defenses consists of ________
- phagocytes
- mast cells
- NK cells
- inflammation
- antimicrobial proteins
- fever
phagocytes work through phagocytosis and are_____
-macrophages; neutrophils; eosinophils
macrophages
the most voracious; “big eaters”
neutrophils
become phagocytic encountering infectious material in tissues
mast cells
bind to, ingest, and kill bacteria; semi-phagocytic manner; release histamine
histamine is a_____
potent inflammatory chemical
NK cells
type of t-lympho that is not specific; interact and kill; go after our own cells that are damaged, infected, or invaded with a virus
inflammation has 4 cardinal signs, they are_____
- heat
- redness
- swelling
- pain
inflammation surrounds the area infected and keeps it_______this alerts the_______ and sets the stage for_____
localized;
adaptive immune sys.;
repair
antimicrobial proteins ______
attack microorganisms by either killing them or eliminating their ability to reproduce
types of antimicrobial proteins_____
interferons and complement
interferons
chemical released by infected cells, the chemicals diffuse to neighboring cells to protect them from the intruder;
-not specific
complements sys. protein
a group of at least 20 plasma proteins that circulate in blood inactive and then when activated it stimulates inflammation
the complement sys . enhances both the______
innate and adaptive defenses
fever
a systemic response to antigens
Phagocytic Mechanism
- a phagocyte recognizes a pathogen’s carbohydrate surface markers ; enhanced in opsonization
- cytoplasmic extensions adhere to pathogen
- pathogen pulled inside the cell in a vacuole called a phagosome
- lysosome binds w/phagosome to form phagolysosome
- lysosomal enzymes digest pathogen and can be aided by respiratory burst if need be for resistant bacteria such as TB and certain other bacteria
- residual body formed and then expelled
NK mechanism
- detect infected or cancerous cells through abnormalities such as a lack of “self” markers called MHC proteins or the presence of certain sugars
- release perforins that punch holes in the cell
- channels appear in target cells and nucleus disintegrates
- attack directly by inducing apoptosis
nk cells are not______or_____
phagocytic or specific
nk cells are not______or_____
phagocytic or specific
inflammatory mechanism
nonspecific response to any tissue injury
- toll-like receptors on macrophages recognize pathogens
- toll-like receptors release cytokines (Cell chemicals) which attract antibodies (positive chemotaxis)
- other cells release other inflammatory mediator chemicals
- vessels in injured area dilate and increase permeability
- hyperemia occurs
- exudate accumulates at site to cause edema (swelling)
dilation causes_______
hyperemia
increased permeability causes____
exudate
hyperemia
increases blood flow and brings more cells and chemicals;
-accounts for redness and heat
exudate
a fluid containing clotting factors and antibodies
results of inflammation
- injured cells release leukocytosis-inducing factors that cause neutrophils to be released in higher than normal amounts from the red bone marrow.
- loss of fluids from dilated vessels (leaky) slows blood flow locally so neutrophils aggregate.
- inflammation causes production of selectins (adhesion molecules) on endothelial cells; holds neutrophils in place (wall of dilate BV) called Margination
- neutrophils undergo diapedesis to go to site of infection
- inflammatory chemicals act as chemotactic agents
- monocytes follow neutrophils to site and become macrophages after leaving the capillaries to replace neutrophils on the battlefield
interferon mechanism
- cells infected by virus release interferons
- IFN’s diffuse to nearby cells
- PKR protein synthesis is stimulated which interferes w/viral replication
- IFR’s also activate macrophages and nk cells
complement system mechanism I aka the______
classic pathway
complement system mechanism II________
lectin pathway
complement system mechanism I
- antibodies bind to pathogens
- complement proteins bind to antibody-pathogen complexes
- lysis, phagocytosis and inflammation result
complement system mechanism II
- complement proteins bind directly to polysaccharide molecules on pathogens
- lysis, phagocytosis, and inflammation result
Fever mechanism
- leukocytes and macrophages exposed to pathogens secrete chemicals called pyrogens
- the pyrogens cause the hypothalamus to raise body temp
- bacteria require iron and zinc (sequestered from the liver and spleen) to replicate
- bacteria are adapted to our body temp so by raising temp some can’t survive
antigen
any substance that provokes/activates immune sys.; foreign substance- intruders aka non-self
adaptive defenses
built-in specific defensive sys
- stalks and eliminates
- must meet or “primed” for pathogen in initial encounter
antigenic properties
- immunogenic
- Reactivity
- antigenic determinants
immunogenic
the ability to stimulate specific lymphocytes to proliferate (multiply)
reactivity
the ability to react w/ the activated lymphocyte and antibodies released by immunogenic reactions
antigen determinants
markers on foreign things
immunocompetent
each lymphocyte must be able to recognize its one specific antigen
complete antigens
immunogenic and reactive
incomplete antigen
hapten (small molecule)
Major Histocompatibility Complex
MHC ( self-antigens)
- everyone has them, but they are unique to every individual
- doesn’t activate immune system unless foreign
characteristics of specific immunity
- involves b & t lymphocytes
1. pathogen specific-only go after one specific pathogen
2. not immediately active-delayed
3. systemic
4. provides memory cells
two pathways for specific immunity (adaptive immunity)
- humoral
2. cell-mediated
humoral pathway
- b-lymphocytes
- free floating pathogens
- antibodies
- b-lymphocyte activated ; temp inactivated
- mark for destruction
cell-mediated
- t-lymphocytes
- go after cellular targets; abnormal MHC
- either act directly to kill it or indirectly by releasing chemicals
lymphocyte production
- produced by stem cells in RBM
- virtually identical until they become immunocompetent
- t- cells become immunocompetent in thymus
- b-cells become immunocompetent in RBM
- naive immunocompetent cells are exposed to antigen in secondary lymphoid organs to mature
- not fully functional until bound w/ antigen
the adaptive immune sys. has 3 cell types and they are__________
- b-lymphocytes
- t-lymphocytes
- APC’s
antigen-presenting cells
- b-lymph, dendritic cells and macrophages act as APC’s
- engulfs pathogen and presents its fragments as antigens on its surface for T-cells to recognize
- naive t-cells can only be activated by antigens that are presented to them on MHC proteins by APC’s
specific immunity
-need an antigen challenge
antigen challenge
- first encounter between naive immunocompetent lymphocyte and antigen
- usually happens in one of the secondary lymphoid organs (tonsils, spleen, etc.)
primary humoral response
- antigens bind w/ surface receptors on naive immunocompetent b lymphocyte ( b-lympho and antigen)
- clonal selection occurs ( copy of lymphocyte);
- most clones become plasma cells (antibodies)
- or some become memory cells
secondary humoral response
same mechanism as primary so the immune response is faster, lasts longer and is more effective
sources of humoral immunity
- active
- passive
- natural active
- natural passive
active immunity
production of antibodies
passive immunity
get antibodies from somewhere else
natural active immunity
body starts the production of antibodies; infection; contact w/pathogen;
natural passive immunity
mom passing antibodies to baby via placenta or breastmilk
active artificial immunity
vaccinations; injected with weakened or dead pathogen; don’t get sick but it causes an immune response
passive artificial immunity
injection of exogenous antibodies (gamma globulin)
antibody structure
4 chains:
- heavy Chains (2)
- light chains (2)
- either t or v shaped
- variable region (V)
- constant region (C)
- antigen-binding site
2 heavy chains
identical to each other
2 light chains
identical to each other; half as long as heavy chains
variable region
- has heavy and light chains
- has the binding receptor on it at the end of the antibody
antigen-binding site
what antigenic determinant binds to
constant region
- only has heavy chains
- determines how pathogens are destroyed
- several classes of antibodies
- at the other end of the antibody
- determines antibody class
- determines which chemicals and cells antibodies can bind to
classes of antibodies
- IgD
- IgG
- IgE
- IgA
- IgM
IgD
receptor on B-lympho surface directing it to bind (receptor)
IgG
- most common type circulating in the bloodstream’
- main antibody for late primary response and beginning of secondary response
- activates/fix complement
- can cross the placenta so baby is born with antibodies (immunity)
IgE
- bind mast cells or basophils causing them to spill histamine, promoting inflammation and allergic reactions
- healthy people have only traces of this
- people w/allergies produce a lot of this so histamine causes the symptoms; production of too much histamine can be fatal
IgA
- found in mucous and other body secretions
- 4 monomers
- stops pathogens from binding to lining
IgM
- can bind to 10?
- 5 monomer
- fixes/activates complement
- first antibody produced primary immune response
- if we know the type of antibodies present, it can determine when infection occurred
- numerous antigen-binding sites
antibody functions
- defense mechanism
- Formation of antigen-antibody complex
- provide site for binding of complement proteins
- block sites on pathogens ( neutralization)
- cause clumping of antigen-containing cells (agglutination- IgM most potent agglutinate)
- cause clumping of soluble antigen molecules (precipitation)
- complement activation- chief defense; trigger lysis
some antibodies are commercially made/produced to use for research and cancer research, they are called_________
monoclonal antibodies
cell-mediated immune response
- t cells bind w/ antigen infected body cell
- co-stimulatory signals are present
- t cell is activated
- clones are produced
- some clones become memory cells
- no antibodies
Types of T-Cells
- cytotoxic
- helper T
- suppressor
CD4 and CD8 cells are not_____
activated
regulatory, cytotoxic and helper cells are_____
activated
Cytotoxic aka CD8
- glycoprotein
- destroy cells in body that harbor anything foreign
Helper T aka CD4
- glycoprotein
- effector cells
- help activate b cells, other t cells, macrophages
- direct adaptive immune response
- some become regulating t cells which moderate immune response
T cell activators
- Class I MHC protein linked antigens
- Class II MHC protein linked
Class I MHC
produced by body inside cell
- cancer cells/virus changing cells
- on the surface of all body cells except RBC
- cd8
Class II MHC
- something outside of cell
- macrophage
- cd4
antigen binding
t cell antigen receptors bind to antigen-mhc complex on surface of apc
co-stimulators
- t cell binding to other receptors on apc, cytokines and interleukins
- each promotes a different response that could either facilitate or disable activation
cytotoxic cells
- release chemicals like perforins and granzymes to destroy infected cell
- have immune surveillance
