what are the two intrinsic systems of the immune system
innate (nonspecific) defense system
adaptive (specific) defense system
immune system
functional system rather than organ system
innate and adaptive defenses intertwined
release and recognize many of same defensive molecules
innate defenses do have specific pathways for certain substances
innate responses release proteins that alert cells of adaptive system to foreign molecules
what are the two lines of defense for the innate defense system
first - external body membranes:skin and mucosa
second -antimicrobial proteins, phagocytes, other cells: inhibit spread of invaders; inflammation most important mechanism
what is the third line of defense
adaptive defense system
it attacks particular foreign substances, so it takes longer to react than the innate system
defensins
antimicrobial peptides which inhibit growth
respiratory system modifications
mucus coated hairs in nose
cilia of upper respiratory tract sweep dust and bacteria mucus toward mouth
internal defenses: cells and chemicals
phagocytes
natural killer (NK) cells
antimicrobial proteins (interferons and complement proteins)
feber
inflammatory response (macrophages, mast cells, WBCs and inflammatory chemicals)
phagocytes
neutrophils: most abundant but die fighting. become phagocytic on exposure to infectious material
macrophages: develop form monocytes -chief phagocytic cells. free macrophages wander through tissue spaces, while fixed macrophages permanent residents of some organ e.g. kupffer cells (liver)
mechanism of phagocytosis
phagocyte must adhere to particle
some microorganisms evade adherence with capsule.
cytoplasmic extensions bind to and engulf particle in vesicle
phagosome fuses with lysosome
opsonization
marks pathogens; coating by complement proteins or antibodies
what cells release respiratory burst and what does it do
helper t cells cause release of enzymes of respiratory burst, which kill pathogens resistance to lysosomal enzymes.
is defensins a mechanism of phagocytosis
yes, it pierces the membrane of the pathogen
natural killer NK cells
nonphagocytic large granular lymphocytes
attack cells that lack "self" cell surface receptors (induce apoptosis)
secrete potent chemicals that enhance inflammatory response
apoptosis
controlled cell suicide
inflammatory response
triggered whenever body tissues injured
prevents spread of damaging agents
disposes of cell debris and pathogens
alerts adaptive immune system
sets the stage for repair
what are the cardinal signs of acute inflammation
redness
heat
swelling
pain
sometimes impairment of function
what are the inflammatory mediators
kinins, prostaglandins, and complement.
-dilate local arterioles
-make capillaries leaky
-many attract leukocytes to area
-some have inflammatory roles
clotting factors form fibrin mesh
scaffold for repair
isolates injured area so invaders cannot spread
steps for phagocyte mobilization
1. leukocytosis: release of neutrophils from bone marrow in response to leukocytosis inducing factors from injured cells
2. margination: neutrophils cling to walls of capillaries in inflamed area in response to CAMs
3. diapedesis of neutrophils
4. chemotaxis: inflammatory chemicals promote positive chemotaxis of neutrophils
interferon and complement proteins
attack microorganisms directly
hinder microorganisms' ability to reproduce
interferon
family of immune modulating proteins
viral infected cells secrete IFNs to warn neighboring cells.
IFNs enter neighboring cells, produce proteins that block viral reproduction and degrade viral RNA; also activate NK cells
complexes precipitate and are subject to phagocytosis
complement fixation and activation
main antibody defense against cellular antigens
several antibodies bind close together on a cellular antigen > complement binding sites on stem regions align which triggers complement fixation into cell's surface to cause cell lysis
does activated complement functions amplify inflammatory response
yes
do T cells directly kill cells
some do. others release chemicals that regulate immune response
what are the two types of t cells
helper T: CD4 usually become helper T, which activate B cells, other T cells, macorphages, and direct adpative immune response. some beomce regulatory T cells which moderate immune response
Memory T cells
CD8 cells become
cytotoxic t cells
destory cells harboring foreign antigens
also become memory T cells
helper cytotoxic and regulatory t cells are all activated T cells, true or false
true
MHC I
displayed by all cells except RBC
MHC II
displayed by APCs (dendritic, macrophages, B cells)
CD8 cells bind to MHC I or MHC II
MHC I
CD4 bind to MHC I or MHC II
MHC II
t cell activation
antigen binding and costimulation
both occur on surface of same APC
both required for clonal selection
who produces B7 proteins
dendritic cells and macrophages produce surface B7 proteins when innate defenses mobilized. it is crucial for a co-stimulatory signal
without t cell co stimulation
they become tolerant to that antigen
are unable to divide
do not secrete cytokines
t cells that are activated
enlarge and proliferate in response to cytokines
differentiate and perform functions according to their T cell class
cytokines
chemical messengers of immune system
mediate cell development, differentiation, and responses in immune system
include interferons and interleukins
role of helper T cells
play central role in adaptive immune response
activate both humoral and cellular arms
without them, there is no immune response
CD4 cells require helper T cell activation into destructive cytotoxic T cells
false; CD8 cells do that
cytotoxic cells
directly attack and kill other cells
activated T cells circulate in blood and lymph and lymphoid organs in search of body cells displaying antigen they recognize
what are the targets of cytotoxic cells
virus infected cells
cancer cells
foreign cells
cells with intracellular bacteria or parasite
perforins
create pores through which granzymes enter target cell
granzymes
stimulate apoptosis
autografts
from one body site to another in same person
isofrafts
between identical twins
allografts
between individuals who are not identical twins
xenografts
from another animal species
how many people have died from AIDS
none; they die from an opportunistic disease because of the weakened immune system due to AIDS
HIV coasted glycoprotein complexes attache to which receptor
CD4
anaphylactic shock
systemic response to allergen that directly enters blood and circulates rapidly
basophils and mast cells enlisted throughout body
systemic histamine release ay cause constriction of bronchioles, tongue may swell, circulatory collapse and death