HOST RESISTANCE AND INFECTION Flashcards
general and serve to protect the body against many harmful substances
non specific host defense
includes INNATE or INBORN resistance observed among species of animals and some persons who have a natural resistance to certain disease
non specific host defense
- physical or mechanical barriers
- intact and unbroken skin
first line of defense
what components are included in the first line of defense?
- skin and mucus membranes
- cellualr and chemical factors
- microbial antagonism
(first line of defense)
___ entrap invaders
sticky mucus
chemical components found in saliva, tears, mucus, and colostrum
SIgA, lysozyme, lactoperoxidase
___ is found in the stomach for gastric mucosal defense
pepsin
(first line of defense)
___ are found in epithelial cell
beta defensins
pH of skin for defense
pH 5.5
pH of gastric acid
pH 1-3
pH of vagina
pH 4.4
protection of the gut
- urination
- expulsion of mucus secretions
- acidity of vagina
___ fight the invasion of new microorganisms in a particular anatomical site
resident microbes
- a glycoprotein with a high affinity to iron
- store and deliver iron to host cells
transferrin
body temperature greater than 37.8C
fever
what cells ingests the toxins released by the bacteria in the blood stream?
phagocytes
ingestine toxins stimulates the phagocytes to produce ___
IL-1
Il-1 stimulates the hypothalamus to produce ___
prostaglandins
what is the function of prostaglandins?
causes the hypothalamic thermostat to be set at a higher level
increased thermostatic reading sends out signals to the nerves surrounding the pvs, causing ___
vasoconstriction
- small antiviral proteins poduced by virus-infected cells
- not virus specific; but species specific
interferons
3 types of interferons
alpha, beta, gamma
human interferons are industrially produced by ___
genetically engineered bacteria
examples of alpha interferons
b cells, monocytes, macrophages
examples of beta interferons
fibroblasts
examples of gamma interferons
t cells, nk cells
a group of approximately 30 different proteins found in normal blood plasma
complement
the proteins interact with each other in a stepwise manner known as the ___
complement cascade
enhances resistance to infection and promoting repair of damagedd tissue
acute phase proteins
- chemical mediators
- enable cells to communicate with each other
cytokines
some cytokines are ___ recruiting phagocytes to location, and direct role in host defense
chemoattractants
normal response to any local injury, irritation, microbial invasion, or bacterial toxin
inflammation
during inflammation, ___ happens to increase blood flow to the site
vasodilation
accumulation of fluid, cells, and cellular debris
inflammatory exudate
thick and greenish yellow susbtance during inflammation
purulent exudate or pus
pyogenic microorganisms in inflammation
staphylococci & streptococci
the process by which phagocytes surrouns and engluf foreign material
phagocytosis
2 most important groups of phagocytes
macrophages, neutrophils
4 steps of phagocytosis
- chemotaxis
- attachment
- ingestion
- digestion
phagocytes move along a concentration gradient
chemotaxis
a directed migration due to the presence of ___
chemotactic agents
coating of pathogens with antibodies in order to increase their susceptibility to ingestion by phagocytes
opsonization
true or false: phagocytes can only ingest objects to which they can attach
True
within the cytoplasm of the phagocyte, th eobject is contained within a membrane-bound vesicle calle ___
phagosome
phagosome fuses with a nearby lysosome to form a digestive vacuole called ___
phagolysosome
___ reduces oxygen to very destructive products such as superoxide anions and hydroxyl radicals
NADPH oxidase
what does NADPH mean?
nicotinamide adenine dinucleotide phosphate hydrogen
where does NADPH oxidase do its job?
in neutrophils
produces hypochlorous acid
myeloperoxidase
the study of the immune system
immunology
the immune system’s way of protecting the body against an infectious disease
immunity
a complex network of organs, cells and proteins that defends the body against infection, whilst protecting the body’s own cells
immune system
physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors
immune response
4 general properties of specific immune response
- recognition
- specificity
- heterogeneity
- memory
- foreign organic substances
- antibody-generating substances
antigens
antigenic determinants; part of the antigen that is recognized by the immune system
epitopes
small molecules that elicit an immune response only when attached to a large carrier such as a proteins
haptens
2 most crucial cells of the specific host resistance
macrophages, lymphocytes
plan an important role in the specific immue response a “antigen-presenting cells”
macrophages
non-granulocytic WBC’s involved in immune response
lymphocytes
2 types of lymphocytes
b cells, t cells
what 2 events must occur for an effective specific immune response?
antigen recognition, lymphocyte proliferation
2 major arms of the immune system
- cell mediated immunity
- antibody mediated immunity
- coordinator of immune regulation
- activates other WBC
helper t cells (Th)
releases cytokine to render the ff:
- stimulate cytotoxic cells to grow and divide
- chemotaxis
- enhancing ability of macrophages to engulf and destroy microbes
helper t cells (Th)
directly kill certain tumor cell, viral-infected cells
cytotoxic t cells (Tc)
binds to foreign cells and then release the ff:
- perforins
- granzymes
cytotoxic t cells (Tc)
what does perforin do?
make holes in infected cell’s membrane
- releases chemicals that suppress the activity of t cells and b cells
- responsible for stopping the immune response
regulatoy t cells (Ts)
- remain after immune suppression
- act as helper t cells on secondary exposure of antigen
memory t cells (Tm)
- associated with certain allergic reactiosn and rejection of transplanted tissues
delayed hypersensitivity t cells (Td)
- produces a variety of chemical substances that recruit defense cells (macrophage)
- bodys defense against cancer
delayed hypersensitivty t cells (Td)
connects helper t cells to macrophages via mhc molecules
cd4 (t4) cells
connects cytotoxic t cells to cells displaying mhc molecules
cd8 (t8) cells
- subpopulation of lymphocytes called granular lymphocytes
- capable of destroying other cells, especially virus infected cells and tumor cells
natural killer cells
- do not proliferate in response to antigen and appear not to be involved in antigen-specific recognition
- not phagocytic but must contact target cell to lyse it
natural killer cells
functions of cytokines
- stimulate cytotoxic cells to grow and divide
- chemotaxis
- enhancing ability of macrophages to engluf and destroy microbes
cytokine that is pyrogenic or induces fever
interleukin 1 / IL1
cytokines that stimulate t cells and b cells to proliferate, also activates NK cells
interleukin 2 / IL2
cytokines that help make tissue cells resistant to viral infection
gamma interferon / Y-IFN
cytokines that activates NK cells and macrophages, also enhances maturation of cytotoxic t cells
gamma interferon / Y-IFN
- cytokines that functions as a WBC growth factor
- stimulates stem cells to produce granulocytes and monocytes
granulocyte-macrophage colony stimuating factor (GM-CSF)
cytokines that activate t cells and macrophages; cell killing
tumor necrosis factor (TNF)
- aka humoral response
- b cells play the major role
- involves the production of antibodies (Ab or Igs)
antibody mediated immune response
soluble proteins produced by activated b cells or plasma cell offsprings in response to an antigen
antibodies (Ab) / immunoglobulins (Igs)
molecular weight of Ab and Igs
150,000 daltons
what is the shape of an Ab and Igs?
y shaped with 4 polypeptide chains; 2 heavy and 2 light
antibody that binds to membranes of basophils and mast cells; allergies
IgE
antibody responsible for internal body secretions
IgA
antibody that is lightest among all classes; can cross the placenta; enables complement fixation
IgG
1st Ab in response to antigen; most efficient complement binding Ig; bacterial to gram (-) bacteria
IgM
what are the effects of antibodies?
- inactivates antigen
- binds antigens together
- activates complement cascade
- initiates release of inflammatory chemicals
- facilitates phagocytosis
antibody production depends on?
- nature of antigen
- site of antigenic stimulus
- amount of antigen
- number of times the person is expose to the antigen
acquired through the normal life expepriences of a human and is not induced through medical means
natural immunity
the consequence of a person developing his own immune respone to a microbe
active immunity
the consequence of one person recieving performed immunity made by another person
passive immunity
produce purposefully through medical procedure (also called immunization)
artificial immunity
- immunity that resulted from infection
- may be long term, may be temporary for some
naturally acquired active immunity
- immunity resulting from vaccination
- attenuated, inactivated, toxoid
artifically acquired active immunity
- mother to fetus
- transplacental transfer
- colostrum
- few weeks or months duration
naturally acquired passive immunity
- humoral antibodies acquired by injection
- lasts for a few weeks
- antivenom, antitoxin
artificially acquired passive immunity
