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
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
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
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:
dissolve bacterial walls
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 _________________
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
rupture the membranes and destroy target cells
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
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
-active complement fragments bind to viruses and bacteria
lectin pathway
binds plasma proteins to particular carbohydrates to initiate reaction cascade
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:
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
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
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
forms clot around the damaged tissue and keeps pathogens out
prevents blood from clotting in vicinity of injury
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
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
dead and dying phagocytes, cellular debris, and living and dead pathogens get surrounded by thick yellowish pus

-accumulates in abscess
pus is usually drained from infection site but if it cannot drain from inflammation site blister may form and may need surgical drainage
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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