Nonspecific Resistance Against Disease

62 cards
Nonspecific Resistance Against Disease

External Barriers, Phagocytosis, Antimicrobial Proteins, Inflammation, Fever

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external barriers (non specific resistance)
 
defends against invasion of pathogens
pathogens
 
disease-producing agents that include infectious organisms, toxic chemicals and radiation
human environment for pathogens
 
human body harbors billions of bacteria because homeostasis provides ideal temperature, moisture and PH nutrients for microbial life
___________ and ____________ are first line of defense against pathogens
 
skin and mucous membranes
skin=
 
too dry and nutrient weak for microbes to survive
epidermal cells and keratin
 
provide mechanical mechanical barriers against microbes
antimicrobial chemicals and lactic acid
 
come from sweat and form coating over skin
sebaceous glands
 
secrete sebum to form protective film over skin
mucous membranes
 
line body cavities that are exposed to the exterior, secretes mucous that traps microbes
areolar connective tissue
 
contains hyaluronic acid which gives it thick, sticky consistency which make it hard for microbes to penetrate them
lacrimal apparatus
 
secrete tears to prevent microbes from infecting eyeballs
saliva
 
dilutes the number of microorganisms and washes them from mouth and teeth
sweat glands
 
produce perspiration to flush microorganisms from the skin
mucous, tears, saliva, and perspiration contain:
 
lysozomes
lysozomes
 
dissolve bacterial walls
urine
 
prevents bacterial growth in urinary system by constantly flushing the urethra
acidic secretions
 
from gastric glands in stomach and in the vagina
-stop bacteria growth in intestinal tract and in female reproductive tract
organisms that get past the skin and mucous membranes are attacked by _________________
 
phagocytes
neutrophils
 
usually phagocytize bacteria but can also kill bacteria with chemicals
killing zone
 
neutrophils release enzyme to form a killing zone around itself
neutrophils contain
 
hydrogen peroxide and hypochlorite
natural killer (NK) cells
 
are large lympocytes made in red bone marrow which can kill a variety of bacteria

-they also can host cancerous or virus infected cells
natural killers release
 
perforins
perforins
 
rupture the membranes and destroy target cells
macrophages
 
develop from monocytes and become scavenger cells
wandering macrophages
 
leave the blood and seek out pathogens
fixed macrophages
 
stand guard in tissues and/or organs and phagocytize bacteria that come to them
antimicrobial proteins
 
provide second line of defense when pathogen penetrates skin and mucous membranes
interferons
 
proteins that are produced and released by cells that are cancerous or infected with viruses

-stimulate uninfected neighboring cells the produce antiviral proteins that will inhibit viral replication

-stimulate phagocytosis and activate NK cells
complement system
 
a group of 30 or more proteins made by the liver and circulate in blood plasma in inactive form
activation by a pathogen....
 
splits complement proteins into fragments that can destroy pathogen by inflammation, immune clearance, phagocytosis and cytolysis
classical pathway
 
requires activation of antibodies
-makes it a part of the immune response
alternative pathway
 
non-specific
-active complement fragments bind to viruses and bacteria
lectin pathway
 
binds plasma proteins to particular carbohydrates to initiate reaction cascade
inflammation
 
local response to tissue damaged-designed to limit spread of pathogen, to remove debris associated with damaged tissue
-initiate tissue repair
characteristics of inflammation
 
redness, swelling, heat and pain
words ending in "itis" indicate:
 
inflammation
occurence of inflammation
 
can occur anywhere in the body but is most common in the skin
mediation of inflammation
 
mediated by cytokine proteins that alter physiology or behavior of the recipient cell
local vasodilation
 
increases blood flow to the damaged tissue causing hyperemia
hyperemia
 
redness and heat in inflamed region
mast cells release
 
histamines, kinins, prostaglandins, and leukotrines
histamines, kinins, prostaglandins and leukotines:
 
increase permeability of blood vessels and promote filtration of fluid from blood into interstitial spaces
soon after inflammation occurs...
 
damaged tissue is flooded with leukocytes

-leads to increased WBC count (inflammation)
when tissue is filled with leukocytes
 
neutrophils cling to the inner walls of the capillaries to signal location of inflammation
diapedesis
 
allows leukocytes to change shape and crawl through capillary walls to interstitial fluid
pathogens are contained and destroyed before...
 
they can spread throughout the entire body
fibrinogen
 
forms clot around the damaged tissue and keeps pathogens out
heparin
 
prevents blood from clotting in vicinity of injury
chemotaxis
 
site of injury or infection
neutrophil are attracted by___________ and begin to ___________________
 
chemicals that guide them to the chemotaxis; and being to phagocytize and destroy bacteria
neutrophils attract __________ and more ______________ by secreting ______________
 
monocytes; and more neutrophil; by secreting cytokines
monocytes
 
arrive 8-12 hours after injury and become wandering macrophages and engulf remaining bacteria, host cells, worn neutrophils and debris
monocytes act as
 
antigen presenting cells
-activate the immune response
pus
 
dead and dying phagocytes, cellular debris, and living and dead pathogens get surrounded by thick yellowish pus

-accumulates in abscess
blister
 
pus is usually drained from infection site but if it cannot drain from inflammation site blister may form and may need surgical drainage
fever
 
an abnormal elevation of body temperature resulting from trauma or infection
fever promotes
 
interferon activity, metabolic rate, inhibits reproduction of bacteria or viruses, and accelerates tissue repair
neutrophils and macrophages
 
secrete fever producing agents to raise hypothalamic set point for body temperature
neutrophils and macrophages :::
 
-causes shivering to generate heat and vasoconstriction to reduce heat loss

-temperature oscillates around new-set-point as long as pathogen is present

-when pathogen is finally destroyed secretion of fever-producing agents halt and hypothalamic set point returns to normal

-vasodilation and sweating occur
reye syndrome
 
in children under 15, some viral infections are followed by Reye syndrome
triggers of reye syndrome
 
aspirin--children shouldn't take aspirin when they have the chicken pox or flu like symptoms
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