objective 2 pt 2 Flashcards
provides resistance against disease
a functional system rather than an organ system
immune system
has both first and second lines of defense
innate defense system
skin and mucus membranes (act as barriers)
first line of defense
antimicrobial proteins, phagocytes, natural killer cells, and inflammation response
second line of defense
Recognizes a foreign substance and attempts to destroy it (takes longer to react than innate)
Involves B and T lymphocytes
Is antigen specific
Produces a Systemic response
has a memory
adaptive defense system
skin and mucous membranes along with their secretions
surface barriers
most microorganisms
physical barrier
resistant to weak acids and bases, bacterial enzymes, and toxins
keratin
provide similar mechanical barriers
mucosae
uses first and or second lines of defense to stop attacks by pathogens
innate defenses
necessary if microorganisms invade deeper tissues
cells and chemicals
what does the second line of defense include?
phagocytes
natural killer cells
inflammatory response
antimicrobial proteins
fever
white blood cells that ingest and digest foreign invaders
phagocytes
most abundant phagocytes, die fighting; become phagocytic on exposure to infectious material
neutrophils
chief phagocytic cells; most robust phagocytic cell
macrophages
process starts when phagocyte recognizes and adheres to pathogen
some pathogens are not killed with the chemicals/enzymes
respiratory burst is then used to kill pathogens
phagocytosis
immune system uses antibodies or complement proteins to
which phagocyte receptors can bind
Act as “handles” for phagocytes to grab on to, enhancing phagocytosis
Phagocyte then engulfs the particle
Creates chemicals/enzymes to aid in destruction of invader
opsonization
enhances cell killing
respiratory burst
also help by piercing membrane of pathogen
defensins
Non-phagocytic, large granular lymphocytes that police blood and lymph
▪kill cancer and virus-infected cells before adaptive immune
system is activated
▪Attack cells that lack “self” cell-surface receptors
▪ Kill by inducing apoptosis (programmed cell death) in Ca cells
and virus infected cells
▪ Secrete potent chemicals that enhance inflammatory
response
natural killer cells
is triggered whenever body tissues are injured
Injuries can be due to trauma, heat, irritating chemicals, or infections by microorganisms
inflammation
what are the benefits of imflammation?
Prevents spread of damaging agents
Disposes of cell debris and pathogens
Promotes healing
Sets the stage for repair
what are the 4 cardinal signs of acute inflammation?
redness
heat
swelling
pain
what are the stages of inflammation?
inflammatory chemical release
vasodilation and increased vascular permeability
phagocyte mobilization
chemical are released by injured tissues, immune cells, or blood proteins
activated macrophages and epithelial cells triggered release of cytokines that promote inflammation
inflammatory chemical release
what are other inflammatory mediators besides histamine?
kinins, prostaglandins, and complement proteins
Vasodilation causes hyperemia—congestion with blood—which leads to
redness and heat
Increased capillary permeability causes exudate—fluid containing clotting
factors and antibodies—to leak into tissue
Results in local swelling (edema)
Swelling also pushes on nerve endings, resulting in pain
vasodilation and increased vascular permeability
what are the benefits of edema?
Surge of fluid in tissue sweeps foreign material into lymphatic vessels for
destruction in lymph nodes
Delivers clotting proteins and complement to area
Clotting factors form fibrin mesh that acts as scaffold for repair
Mesh also isolates injured area so invaders cannot spread
injured cells release leukocytosis-inducing factors
leukocytosis
neutrophils cling to capillary walls marked by cell adhesion modules that signal ‘this is the place’
margination
neutrophils flatten and squeeze out the capillaries
diapedesis
neutrophils follow chemical trait of chemotactic agents and devour foreign material
chemotaxis
how do antimicrobial proteins enhance innate defenses?
attacking microorganisms directly
hindering microorganisms ability to reproduce
what are the most important antimicrobial proteins>
interferons
complement proteins
immune modulating proteins; cells infected with viruses
can secrete IFNs that “warn” healthy cells; IFNs also activate NK
cells and macrophages
interferons
proteins that circulate in blood in inactive
form; activation produces a cascade of events that enhance
inflammation & directly destroys bacteria; cell lysis begins when
these proteins bind to target cell membrane; then water flows in and
lysis of microbe occurs; enhances both innate and adaptive defenses
complement proteins
Abnormally high body temperature that is a systemic response to invading
microorganisms
fever
what are the benefits of a moderate fever?
Causes liver and spleen to isolate iron and zinc (needed by microorganisms)
Increases metabolic rate, which increases rate of repair
a specific defensive system that eliminates almost any pathogen or abnormal cell in the body
adaptive immune system
what are the activities of adaptive immune system?
amplifies inflammatory response
activates complement
must be primed by initial exposure to specific foreign substance
shortcoming
what are the characteristics of adaptive immunity?
It is specific: recognizes and targets specific antigens
Systemic; not restricted to initial site
Has memory: mounts an even stronger attack to “known” antigens
what are the 2 main branches of adaptive system?
humoral
cellular
Involves B cells
Antibodies, produced by lymphocytes, circulate freely
Bind temporarily to target cell
Temporarily inactivate
Mark for destruction by phagocytes or complement
Targets antigens from pathogens that are freely circulating, or outside the
infected cells (extracellular)
humoral immunity
Involves T cells
Lymphocytes act against target cell:
Directly
Indirectly
occurs inside infected cells; cellular targets (intracellular)
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cellular immunity
act against target cells
directly
by releasing chemicals that enhance inflammatory response; or activating other lymphocytes or macrophages
indirectly
what are the 4 characteristics that set adaptative immunity apart from innate defenses?
1.It involves lymphocytes called B and T Lymphocytes
2. It is Specific
3. It is Systemic
4. It has “memory
what are the 2 types of lymphocytes?
B lymphocytes
T lymphocytes
humoral immunity
B lymphocytes
cellular immunity
T lymphocytes
B cell originates and develop in the bone marrow(inactive called Naïve B
cells)
* Released from bone marrow, naïve B cells circulate in lymph
* When B cell encounters target antigen, and antigen binds to receptor
(activates it) it provokes humoral immune response (lock & key)
Antibodies specific for that particular antigen are then produced
humoral immune response
secrete antibodies
plasma cells
clone cells that do not become plasma cells become…
memory cells
Provide immunological memory
Mounts an immediate attack against the same antigen in future encounters
Memory cells provide humoral immunological memory
memory cells
what are the 2 types of humoral immunity?
naturally acquired
artificially acquired
formed in response to actual bacterial or viral infection
antibodies delivered to fetus via placenta or to infant
through milk
naturally acquired
formed in response to vaccine of dead or attenuated pathogens
short term immunization by the injection of
antibodies ie: gamma globulin
artificially acquired
occurs when a ready made antibodies are
introduced into the bloodstream
passive humoral immunity
proteins secreted by plasma cells
made up of gamma globulin portion of blood
antibodies or immunoglobulins
first antibody released during primary immune response
Potent agglutinating agent
Readily fixes and activates complement cascade
IgM
found in mucus and other secretions (saliva, sweat, milk, intestinal juice)
Helps prevent entry of pathogens
IgA
Attached to surface of B cells
Functions as B cell receptor (activates B cells)
IgD
accounts for 75–85% of circulating antibodies
Main antibody of late primary and secondary responses
Crosses placental barrier
IgG
active in some allergies and parasitic infections; found in lung, skin & some mucus membranes
Causes mast cells and basophils to release histamine
IgE
Required for full activation of most B and T cells
Activate macrophages
Release cytokines
Become memory T cells
Without helper T cells there is no adaptative immune response
Activate both humoral and cellular immunity
helper T cells
Directly attack and kill
Activated TC cells target:
Virus-infected cells
Cells with intracellular bacteria or parasites
Cancer cells
Foreign cells (transfusions or transplants)
Conduct immune surveillance with NK cells
Become memory T cells
cytotoxic T cells
Dampen immune response
Important in preventing autoimmune reactions
Suppress B cell immune response to maintain homeostasis
regulatory T cells
