Bi 127 Kryger Lecture Exam 2

host

host

any organism that harbors another organism

Symbiosis

relationship in which two species live closely together

Mutualism

symbiosis in which both organisms benefit

Commensalism

symbiosis that is beneficial to one organism, and the other organism is not affected.

parasitism

symbiosis that is beneficial to one organism and harmful to the other.

host-parasite relationship

any infectious disease is what kind of relationship?

parasite

the microbe, the organism that benefits in a host-parasite relationship

pathogen

a parasite that causes disease in its host

disease

outcome of fight between parasite and host

parasites

when a disease occurs in the host, who won the fight?

hosts

when an organism infects a host, but causes no disease, who won the fight?

colonization

microbe is present and possibly multiplying at an epithelial surface, but the effect on the host in negligible

infection

multiplication of the microbes in the host, but no substantial effect on the host

disease (sequence of conditions)

microbe is present and multiplying with clear adverse effects on the host

pathogenicity

ability to cause disease

an organism's pathogenicity depends on it's ability to: (3 things)

invade the host, multiply in the host, avoid being damaged by host defenses

Frank pathogens (aka. True pathogens or Primary pathogens)

frankly, they cause disease! in normal healthy hosts.

opportunistic pathogens

not considered pathogenic in normal healthy person, only when opportunity arises in certain hosts

predisposing factors that allow opportunistic pathogens to cause disease (3 things)

host is immunocompromised or immunosuppressed, microbes establish in part of the body that isn't natural to them, or normal flora is disrupted.

immunocompromised

disease causes immune system to weaken

immunosuppression

medication prevents immune system to weaken

nonpathogen

microbes that do not cause disease

virulence

intensity of disease produced by pathogen, or the degree of pathogenicity

the virulence of a microbe is determined by it's ability to: 2 things

establish itself in a host, and cause damage

highly virulent

produce intense infection with significant amount of disease

low virulence

less significant effects on host

Example of Highly Virulent Pathogen

rabies virus

rabies causes what symptoms?

severe neurologic symptoms or death

Example of Low Virulent Pathogen

cold virus

avirulent

unable to cause disease, aka nonpathogenic

other terms for normal flora

indigenous flora and microbiota

normal flora

all microbes that live on and within a healthy human body

there organisms are colonizing the host, and not typically associated with disease

normal flora

How does colonization differ from infection?

colonization occurs at epithelial surfaces of body, and infection means organisms have entered the body

resident flora

Permanent residents of the healthy human body

transient flora

temporary residents that are present only under specific conditions

transient flora are acquired from where?

external environment

transient flora are attracted to what?

warm and moist body areas

what are reasons that transient flora are only temporary? (4)

washed away, unable to compete with resident flora, unable to survive with changes in pH, flushed away by body secretions

body sites with normal flora (not specific, but generally)

areas with more exposure to the outer world

types of body sites lacking normal flora

fluids and internal tissues and organs

sources of normal flora

birth canal, contact with people, food, air and objects in the environment

benefits of normal flora

helps immune system become stronger

nutritional benefit of normal flora, and how they help

vitamin k and b12 produced by intestinal bacteria. they compact feces, preventing diarrhea

how does microbial antagonism prevent pathogens from colonizing?

by taking up nutrients, oxygen and space

immunostimulation

immune system activation

how does immunostimulation benefit the immune system?

flora provide a constant source of antigens and irritants to stimulate with immune system

hygiene hypothesis

Studies have shown that germ-free mice have a weakened immune system

pathology

the study of the structural and functional manifestations of disease

pathogenesis

the steps or mechanisms involved in the development of a disease

steps in the pathogenesis of infectious diseases (not detailed)

entry, attachment, multiplication, invasion, evasion, damage

Virulence

degree of pathogenicity

virulence factors

structural or physiological characteristics that help organisms cause disease

general types of virulence factors

adhesion, exoenzymes, toxins, and protective mechanisms against host defenses

adhesion

the process in which the microbes gain a stable foothold at the portal of entry

ahdesins

proteins found on fimbriae and capsules, involved in adhesion

viral spikes

act as adhesion factors

adhesins enable a microbe to do what?

colonize

exoenzymes created where?

inside the cell, then move to the outside

exoenzymes

enzymes secreted by microbes that invade tissues, inflict damage on them, and escape host defenses

examples of exoenzymes

end in -ase

mucinase

breaks down protective coating on mucous membranes

mucinex is the medication, mucinase is the...

enzyme

coagulase

clots plasma, forming a plasmin clot around the bacterium to protect it from phagocytes, antibodies and other host defenses.

streptokinase and staphylokinase

dissolve clots, which allow the pathogen to escape

-kinesis, -kinetic

movement

hyaluranase

breaks down hyaluronic acid to enable the pathogen to spread through connective tissues

hyaluronic acid "aka"

tissue cement

collagenase

Breaks down collagen, the principle fiber in connective tissue, so that pathogen can spread further

hemolysins

lyse red blood cells and breakdown hemoglobin to release iron

necrotyzing enzymes do what?

destroy tissues

toxins

poisons that microbes produce to kill host cells or disrupt host processes

two major types of toxins

endotoxins and exotoxins

endotoxin

an integral part of the gram-negative cell wall; it causes adverse physiological effects in the host

endotoxin is part of what?

lipopolysaccharide

lipopolysaccharide

part of the outer membrane of gram-negative cell walls that is released when bacteria are killed

shock

very low blood pressure, therefore not enough blood flow to other organs, therefore some organs shut down due to lack of blood

endotoxin does what?

activates clotting factors and complement in the host, causing endotoxic shock

Symptoms of endotoxic shock

low blood pressure, fever, ad Disseminated Intravascular Coagulation

disseminated intravascular coagulation

clotting in all the wrong places, causing hemorrhaging

exotoxins are produced and released by what?

the pathogen

neurotoxin

acts on nervous system

enterotoxin

acts on GI tract

leukociden

acts on leukocytes (white blood cell) host defenses

cytotoxin

acts on cells

exotoxins are categorized based on what?

their targets

exotoxin disease associations

infections and intoxications

infections (when compared to intoxications)

the pathogen has infected the body and releases it's enzymes.

toxins spread from the site of infection to cause what?

disease

intoxications

diseases resulting from ingestion or absorption of toxins. no infection is involved.

Antiphagocytic factors

Protect bacteria from being engulfed and ingested by phagocytes (host defense cells)

some bacteria produce ____ to destroy WBCs.

leukocidins

some bacteria secrete ___, which makes it difficult for a phagocyte to engulf them.

capsules

capsule

thick glycocalyx

some bacteria are ______(5 words) after ingestion

adapted for survival inside phagocytes

survival inside phagocytes has special significance because...

it provides a place for the microbes to hide, grow, and be spread throughout the body

Signs of disease definition

objective evidence of a disease. testable/measurable.

symptoms of disease definition

subjective evidence of a disease. feelings perceived only by the patient

syndrome

a combination of signs and symptoms that occur together and are indicative of a particular disease or abnormal condition

acute disease

rapid onset, short duration