is a population of microorganisms that infect the body w/out causing disease
Some normal flora establish
a permanent relationship with in the body, while others are only the a limited amount of time
the relationship between the body and its normal flora
symbiosis is benifiecial to:
both the body and the microorganisms
is the relationship of flora and the body
an example of mutualism is
lactobacillus, living in the vagina
lactobacillus derive nutrients through
the environment while producing acid to prevent the overgrowth of other organisms
is the ability to cause a disease of a parasite.
is one in which the symtoms are apparent
is accompanied by a few obvious symptoms
is the progess and transmission of disease
refers to the time between entry of the organism into the body and the appearance of clincal signs of the disease.
Variablility of incubation periods depends on
the characteristics of the organism and could be days or even months
the incubation period in AIDS
is the time the organisms reproduce until there are sufficient number to cause advers effects in the body(which may be up to 10 years , thats w/ out rx
follows the incubation period. The time when the infected person may feel fatigued, lose appetite or have a headache, usually sensing something is wrong
follows prodromal period, when the die=sease develops fully and the clinical symptoms reach a peak,
The length of the acute period
depends on the virulence of the particular pathogen and the host resistance.
Host resistance is an example of
how strong the persons immune system is
Acute period usually ends when:
the host resistance becomes effective(ex. immune system mobilizes), or can end when sufficient nutrients for the number of microbes deline or when they are affected by wastes from dead organisms and necrotic tissuem thus decreasing their reproductive rate.
the symptoms subside
Recovery or Convelescent period
the period following the decline period, when the body's system returns to normal
infection is not totally eradicated, some organisms remain in the body, causing chronic infection.
in these cases clinical signs are mild , although there may be periodic acute episodes.
which is a situation in which the pathogens are circulating in the blood and reproducing, affecting all systems and threatening life(aka, blood poisoning)
septicemia is likely to occur when
there is a virulent organism involved, when body defenses are compromised, or when organisms are resistant to drugs
Transmission (2 general) are
Indirect and direct
direct transmission involves
hand-shaking, kissing, sexual intercouse, like w. gonorhea, and genital herpes
Direct contact can also mean exposure to
droplets,from a cough or a sneeze,
direct contact diseases that are spread by droplets are
influenza, measlesm pertussis(whooping cough), and streptococcal sore throat.
for some disease direct contact w/ an animal could result like with:
rabies from an animal
indirect methos fo disease transmission include:
consumption of contaminated food or water as well as contact with foites(inanimate objects that carry disease organisms(ex bed linens).
foods may be contaminated by
handling processess or eating diseased animal meat
Arthropods are a representaion of
indirect method for transmission
Vectors are,Living organisms (like arthropods) that
carry disease agents from one host to another
an arthropod that transports microorganisms on its legs and other body parts.
the arthropod is diseased itsself
an organism that harbors disease agents but shows no sign of disease
one who has recoved from the disease, but continues to spread the disease.
is transmissible among hosts
passes with particular ease among hosts
singular events wher the agent is acquired directly form the environment and is not easily transmitted to the next hoist.
occurs at a low level in a certain geographic area
explostion of disease, that occurs at low level in a certain geographic area
is a wold wide explostion of disease
Bacteria must have certain _______ to cause disease
Certain capabilities of the organisms are
portal, dose, invasivness,
portal refers to the capability of the organism to
enter the site of the host in anticipation of disease
the Dose refers to
the number of parasites that must be taken into the body for disease to be estblished.
Invasiveness refers to the bacteria's ablility to:
penetrate tissues and cause structural damage
act on host cells and interfere with certain functions meant to retard invasion
is an enzyme that catalyzes the formation of a blood clot( which protects bacteria from phagocytosis)
is a bacterial enzyme that dissolves fibrin clots that the body make to restric tand isolate an infected area.
enhances penetration of a parasite through tissue by digesting gyaluonic acid that binds cells together in a tissue.
microbial poisons that are released into the surrounding environment of the tissue as they are produced (exo=outside)
are microbial poisons that are part of the cel wall of bacteria and are released upon disintegration of the parasite.
Role of leukosites and the lymph system
to phagocytize bacteria, fungi, and some viruses,
Polymorphonuclear cell or PMN's aka
Nuetrafils, WBC's. luekocytes
phagocytize bacteria, fungi, and some viruses
moderate allergic reactions and defend against parasitic worm infestation
function in allergic reactions and relase histamine which promotes inflammtaion.
leave the blood stream and become macrophages tha phagocytize bacteria, dead cells and other debris.
Lymphocytes funtion in the immune system as
T-lymphocytes funtion as
cell mediated immunity
is the cell-free fluid that surround tissue cells and fills the intercellular spaces it is pumped along in tiny vessels by the contraction of skeletal muscle cells.
Lymph nodes are
pockets of lymphocytes, phagocytes, and lymphatic tissue along the lymph vessels
2 types of resistance
specitfic and non-specific
is resistance to diseases that involve a broad series of factors.
is immunity that exists in one species of organisms but not other species.
exists in one race of humans but not other races.
mechanical and chemical barriers are
things such as skin, mucous membranes, mucus, cilia, and stomach acid.
Seek out and engulf foreign particles
is a process that limits the extent of the injury.
inhibits the growth of certain organisms
natural killer cells
roam the body in blood and lymph and kill cancer cells and virus-infected cells before the immune system is enlisted
develops from the response byt the bodys;s immune system to antigens(large, complex molecules that the body interprets to be non-self)
large complex molecules that the body interprets to be non-self
Cell mediated- and Humoral immunity are
are stimulated to form antibody-producing plasma cels
antibodies are formed
in the lymph nodes .
antibodies enter the circulation and reach int infection site,
where they act agianst the bacteria
Active Immunity to disease
derived form an exposure ato antigens and subsequent production of antibodies.
naturally acquired immunity
is immunity that usually follows a bout of illness, howerver not always the case, sublcinical diseases may bring on the immunity. (nature, exposed)
is immunity that is developed after an intentional exposure to antigens followed by an immune response(vaccines)
delops when anitbodies enter the body from an outside source,
Naturally aquired Passive immunty
immunity develops when antibodies pass into the fetal circulation form the mothers bloodstream via the placenta and the unmi8lbical cord.
Artificial aquired passive immunity
arises form the intention injection of antibody -rich serum into the circultion