Non-Specific Resistance Against Disease Flashcards
nonspecific resistance is
innate, or built-in protection against invasion by a wide range of pathogens
pathogens are
disease-producing agents that include infectious organisms, toxic chemicals, radiation
human body harbors billions of bacteria because
homeostasis provides ideal temp, moisture, pH and nutrients for microbial life
the first line of defense against pathogens are
the skin and mucous membranes
skin is typically too
dry and nutrient poor for microbes to survive
epidermal cells and keratin provide
mechanical barrier against microbes
coat of antimicrobial chemicals and lactic acid from sweat cover
skin and protect from pathogens
sebaceous glands secrete
oily sebum to form protective film over skin
mucous membranes line
body cavities that are open to the exterior and secrete mucous to trap microbes that try to enter these cavities
areolar connective tissues contains
hyaluronic acid which gives it thick and sticky consistency that makes it difficult for microbes to penetrate
the lacrimal apparatus secretes
tears to keep microbes from infecting the eyeballs
saliva dilutes
the number of microorganisms and washes them from the teeth and mouth
sweat glands produce
perspiration to flush microorganisms from the skin
mucus, tears, saliva, and perspiration contain
lysozyme which dissolves bacterial walls
urine prevents
microbial growth in the urinary system by constantly flushing the urethra
acidic secretions from gastric glands in the stomach and glands in the vagina retard
bacterial growth in the intestinal tract and female reproductive tract, respectively
organisms that get past the skin and mucous membranes are
attacked by phagocytes
phagocyte adheres to a pathogen by
recognizing its carbohydrate signature
neutrophils usually
phagocytize bacteria, but they can also kill bacteria with chemicals
neutrophil releases enzymes to form
a “killing zone” around itself which kills many more bacteria than it could destroy by phagocytosis
killing zone typically contains
hydrogen peroxide and hypchorite to kill bacteria but neutrophil also dies
-may contribute to the development of rheumatoid arthritis
natural killer (NK) cells are
large lymphocytes produced in red bone marrow, which kill a wide variety of bacteria and host cells that have become cancerous or gotten infected with viruses
when a natural killer cell encounters a microbe or an abnormal host cell,
it secretes perforins to rupture membrane and destroy target cell
natural kills cells are found in
blood, the spleen, lymph nodes, and red bone marrow
macrophages develop from monocytes and become
scavenger cells
wandering macrophages
leave the blood to seek out pathogens in the tissues
fixed macrophages
stand guard in certain tissues and/or organ and phagocytize pathogens that come to them
antimicrobial proteins provide
a second line of defense against bacteria and viruses that penetrate the skin and mucous membranes
interferons are
proteins that have been produced and released by cells that have become infected with viruses
interferons stimulate
uninfected neighbor cells to manufacture antiviral cells that can interfere with or inhibit viral replication
**not virus specific
the complement system describes
a group of 30 or more proteins that are synthesized by the liver and circulate in the blood plasma in an inactive form
activation of the complement system by a pathogen
splits one of these proteins into fragments that can destroy pahtogen by inflammation or immune clearance or phagocytize or cytolysis
classical pathway requires
activation of antibodies which makes it part of immune response
alternative pathway is
non-specific
-active complement fragments can bind to viruses or bacteria or yeast
lectin pathway binds to
plasma proteins to particular carbohydrates to initiate a reaction cascade
inflammation is a
local response to tissue damage that is designed to limit the spread of a pathogen, to remove debris associated with damaged tissue, and to initiate tissue repair
inflammation is characterized by
redness, swelling, heat, and pain
-words that end in -itis
inflammation is mediated by
small cytokine proteins that alter physiology or behavior of recipient cell
local vasodilation
increases blood flow to the damaged tissue and causes hyperthemia, which produces redness and heat in the inflamed region
mast cells release
histamines and other cells release kinins, prostaglandins, and leukotrines, all chemicals increase permeability of blood vessels and promote filtration of fluid into interstitial space
swelling (edema) presses on
nerve endings
-this combines with bacterial toxins and prostaglandins, kinins to produce pain sensations
swelling is good because
fluids move foreign substances into the lymphatic system also delivers compliment proteins and clotting factors to damaged tissue
soon after inflammation begins,
the damaged tissue gets flooded with leukocytes, which leads to the increase in white blood cell count that is characteristic of inflammation
neutrophils accumulate in
capillaries to identify inflammation site
diapedesis allows
leukocytes to change their shape and crawl through capillary walls to enter interstitial fluid
pathogens must be contained and destroyed before
they can spread throughout the body
fibrinogen filters into
fluid around a damaged tissue and forms a clot which sequesters bacteria and any other microbes
heparin prevents
the blood from clotting in the immediate vicinity of the injury so any pathogens that are present get trapped in fluid-filled clot
neurtophils are attracted by
chemicals that guide them to the site of injury or infection behin to phagocytize and destroy trapped bacteria
neutrophils recruit
monocytes and more neutrophils by secreting cytokines
monocytes arrive with
8-12 hours following injury and become wandering macrophages engulfing any remaining bacteria, damaged host cells, worn out neutrophils, other debris
dead and dying phagocytes, cellular debris, and living and dead pathogens get surrounded by
a thick yellowish pus, which accumulates in an abscess
pus is usually
absorbed from the infection site, but if it cannot drain form the inflamed region a blister may form and require surgical drainage
fever is
abnormal elevation of body temperature due to invading microorganisms
fever promotes
interferon activity, elevates metabolic rate, inhibits reproduction of bacteria and viruses and accelerates tissue repair
neutrophils and macrophages secrete fever producing agents to
raise the hypothalamic set-point for body temperature
the raise in the hypothalamic set-point for body temperature causes
shivering to generate heat and vasoconstriction to reduce heat loss
-temp oscillates around the new set point as long as the pathogen is present
when the pathogen is finally defeated,
the secretion of fever-producing agents halts, set point returns to normal, vasodilation and sweating occur
in children younger than 15 some viral infections may be followed by
Reye syndrome
Reye syndrome
is where brain swelling produces nausea and vomiting, seizures, and come
Reye syndrome can be triggered by
aspirin, parents are cautioned not to administer aspirin to children with chicken pox or flu-like symptoms
