Like this study set? Create a free account to save it.

Sign up for an account

Already have a Quizlet account? .

Create an account


means "to live together"


describes the relationship between microorganisms and their host

Mutualism, Commensalism, and Parasitism

What are the three types of symbiotic relationships?


type of symbiotic relationship in which both organisms benefit from the relationship

examples of mutualism

Trichonympha (protozoan) in Termite intestines; and Vitamin-synthesizing bacteria in the human colon


type of symbiotic relationship in which one organism benefits from the relationship and the other neither benefits nor is harmed

Staphylococcus sp. on the human skin

what is an example of a Commensalistic relationship?


type of symbiotic relationship in which one organism benefits from the relationship (parasite) and the other is harmed (host)

Pathogenic organisms in the body

What is an example of a Parasitic relationship?

Normal Microbiota

the organisms that colonize the body's surfaces without normally causing disease (AKA Normal Flora or Indigenous Microbiota)

Resident Microbiota and Transient Microbiota

What are the two types of Normal Microbiota?

Resident Microbiota

Which type of Normal Microbiota is part of the Normal Microbiota throughout life?

Resident Microbiota

Normal Microbiota that are usually Commensal

Resident Microbiota

Type of Normal Microbiota that feeds on excreted cellular wastes and dead cells

Resident Microbiota and Transient Microbiota

Found on the skin, and on Mucous Membranes of the Digestive tract, upper respiratory tract, and distal part of the urethra and vagina

Transient Microbiota

Which type of Normal Microbiota remain in the body for only hours to months before disappearing?

Transient Microbiota

Which type of Normal Microbiota cannot persist in the body due to competition from other microorganisms, elimination by the body's defense cells, and chemical or physical changes in the body that expel them?

birthing process

Microbiota begins to develop during the _________ ________.


Much of one's _________ Microbiota is established during the first months of life.

Opportunistic pathogens

normal microbiota or other normally harmless microbes that can cause disease under certain circumstances

Conditions that provide opportunities for Pathogens

Immune Suppression, Reduction in Microbial Antagonism, and introduction of Normal Microbiota into an unusual site in the body

Factors that can suppress the immune system

Disease, malnutrition, physical or emotional stress, extremes of age, radiation and chemotherapy (for cancer treatment), and Immunosuppressive Drugs (for organ transplants)

microbial antagonism

Candida albicans (yeast) may cause vaginal infections with long-term antibiotic therapy. This is an example of a reduction in what?

example of a normal microbiota being introduced into an abnormal part of the body

Escherichia coli is usually nonpathogenic in the colon, but can cause UTIs in the urethra


the mere presence of Microbes in or on the body


results when the organism has evaded the body's external defenses, multiplied, and become established in the body

skin, mucous membranes, placenta, and parenteral route

What are the four major types of portals of entry into the body?

portals of entry

sites through which pathogens enter the body

natural openings or cuts

Some Pathogens enter the skin through what?

by burrowing into or digesting the outer layers of skin

How do Hookworm Larvae (parasitic roundworms; adults of which live in intestines) and Blood Fluke Larvae (parasitic flatworms; adults of which live in blood vessels in the liver) enter the body?

Hookworm Larvae

parasitic roundworms; adults of which live in intestines

Blood Fluke Larvae

parasitic flatworms; adults of which live in blood vessels in the liver

Mucous Membrane

type of portal of entry that lines the body cavities that are open (meaning it has a natural opening) to the environment

Respiratory Tract

what is the most commonly used site of entry?

Cold and Influenza Viruses

What usually enter the body via contamination of Conjuctiva by fingers, and then are carried into the Nasal Cavity by tears?


Pathogens able to survive the acidic pH of the stomach may use the ______________ tract as a route of entry

Parenteral Route

deposition directly into tissues beneath the skin or mucous membranes; NOT A TRUE PORTAL OF ENTRY, but a means by which typical portals of entry can be circumvented

Punctures, cuts, deep abrasions, and surgery

Pathogens can enter the body through the parenteral route by __________, ____, ____ _________, and _________.


process by which microorganisms attach themselves to cells; it is required to successfully establish colonies within the host

Adhesion Factors

Used in Adhesion and include Specialized structures such as Adhesion Discs in some protozoans, hooks and suckers in some helminthes, and Ligands (called Adhesins in bacteria and Attachment Proteins in viruses)


surface Lipoproteins and glycoproteins that enable bacteria and viruses to bind to complementary receptors on host cells


What are Ligands called in Bacteria?

Attachment Proteins

What are Ligands called in viruses?

Interaction of a Ligand with a host receptor

What can determine specificity of microorganisms for host cells?

Neisseria gonorrhoeae

bacteria that has Adhesins on its Fimbriae that stick to cells lining the human Urethra and Vagina

The ability to change or block the Ligand or its Receptor

What can prevent infection (in regards to Adhesion Factors)?


The inability to make Adhesins or Attachment Proteins renders the microorganism ________.


Infection is the invasion of the host by a pathogen, whereas _________ occurs if the invading pathogen alters the normal functions of the body


Another term for disease; any change from a state of good health


subjective characteristics of disease felt only by the patient


objective manifestations of disease that can be observed or measured by others


group of symptoms and signs that characterize a disease or abnormal condition

Asymptomatic (or Subclinical) Infections

Infections that lack symptoms, but may still have signs of infection


study of the cause of disease

Germ Theory of Disease

the theory that disease is caused by infections of Pathogenic Microorganisms

Robert Koch

Who developed a set of postulates one must satisfy to prove a particular pathogen causes a particular disease?


Is using Koch's postulates feasible in all cases?

Why using Koch's Postulates is not feasible in all cases

Some Pathogens cannot be cultured in the laboratory, some diseases are caused by a combination of Pathogens and other Cofactors, and the fact that ethical considerations prevent applying Koch's postulates to Pathogens that require a human host

Mycobacterium leprae

Pathogenic bacteria that has never been grown on lab media

Hepatitis B and Hepatitis D

Liver cancer can occur when liver cells are infected with both _________ and __________ viruses, but usually not when infected by only one of them. (example of a disease caused by a combination of Pathogens and other Cofactors)


Example of a Pathogen that requires a human host, and therefore should not be used in Koch's Postulates for ethical reasons.

Pneumonia, Meningitis, and Hepatitis

What are 3 diseases that can be caused by more than one pathogen?


the ability of a microorganism to cause disease


the degree of pathogenicity

Virulence factors

_________ _______ contribute to an organism's virulence

Types of Virulence Factors

Adhesion Factors, Biofilms, Extracellular Enzymes, Toxins, and Antiphagocytic Factors

Extracellular Enzymes

Enzymes secreted by the Pathogen that act as Virulence Factors and dissolve structural chemicals in the body

maintain infection, invade further, and avoid body defenses

What do Extracellular Enzymes help the Pathogen do?

Hyaluronidase, Collagenase, Coagulase, Staphylokinase, and Streptokinase

What are the 5 Extracellular Enzymes?


Extracellular enzyme that breaks down Hyaluronic Acid, which holds animal cells together.


Extracellular Enzyme that digests Collagen, which is the main structural protein in the body.


Extracellular enzyme that causes Coagulation (blood clotting) to surround bacteria and protect them from host defenses


Extracellular enzymes that break up blood clots, enabling the bacteria to spread (includes Staphylokinase and Streptokinase)


Chemicals that harm tissues or trigger host immune responses that cause damage


the presence of Toxins in the bloodstream that are carried beyond the site of infection

Exotoxins and Endotoxins

What are the two types of Toxins?


Proteins or Peptides secreted by microorganisms that destroy host cells or interfere with their metabolism

Cytotoxins, Neurotoxins, and Enterotoxins

What are the main types of Exotoxins?


toxins that kill host cells or impair their function


toxins that adversely affect nerve cell function

Clostridium tetani and Clostridium botulinum

what are 2 examples of bacteria that secrete neurotoxins?


toxins that adversely affect cells lining the G.I. tract

Staphylococcus aureus and Escherichia coli

What are 2 pathogenic bacteria that secrete enterotoxins?


Lipid portion of the Lipopolysaccharide of the Outer Membrane of Gram (-) Bacteria released when cells die


What kind of toxins stimulate the body to release chemicals that cause fever, inflammation, bleeding, diarrhea, shock, and blood clotting?


Antibodies that bind to Toxins and neutralize them


heat or chemically-treated Toxins that are inactive, but stimulate production of Antitoxins by the host

Antiphagocytic factors

Certain factors which prevent Phagocytosis by the host's phagocytic cells

Bacterial Capsules and Antiphagocytic chemicals

What are 2 antiphagocytic factors?

Bacterial Capsule

What is the antiphagocytic factor that is often composed of chemicals found in the body and not recognized as foreign?


Bacterial Capsules can be _________, making it difficult for Phagocytes to engulf the bacteria

Antiphagocytic Chemicals

Antiphagocytic factors, some of which prevent fusion of Lysosomes and Phagocytic Vesicles to block digestion of microbes.

M protein

Antiphagocytic Chemical that resists phagocytosis and is on cell walls and fimbriae of Streptococcus pyogenes


Antiphagocytic chemicals that directly destroy phagocytic white blood cells

5 stages

Many infectious diseases have __ _____ following infection

Incubation Period

time between infection and appearance of first symptoms or signs of disease

Incubation Period

The length of the _________ ______ of a disease depends on the Virulence of the pathogen, size of the inoculum, the pathogen's generation time, site of infection, and state of the host's immune system.

Incubation Period, Prodromal Period, Illness, Decline, and Convalescence

Name the stages of infectious disease in order

Prodromal Period

second stage of infection; short time with only mild symptoms (Malaise, muscle aches) before illness


third stage of infection; time of most severe symptoms and signs, since the host's immune response is not at its maximum


fourth stage of infection; time when the immune response peaks and/or medical treatment overcomes the Pathogen, so the body begins to return to normal


fifth stage of infection; time when host recovers, tissues are repaired, and the body returns to normal

during all stages

During which stages is the host usually infectious?


virus that can be spread even when there are no obvious lesions

Portals of Exit

Through what do pathogens leave their host?

Portals of Entry

Many Portals of Exit are the same as their _______ __ _____.

body secretions or body wastes

With what do pathogens usually exit the body?


Can most pathogens survive long outside of their host?

Reservoirs of Infection

sites where Pathogens are maintained as a source of infection

Animal, Human, and Nonliving

What are the three types of Reservoirs?


diseases that are naturally spread from their usual animal host to humans (over 150 known, including Yellow Fever, Bubonic plague, and rabies)

ways to acquire Zoonoses

through direct contact with an infected animal or its waste, by eating animals, or from bloodsucking Arthropods

dead end hosts

Humans are usually ____ ___ ____ to Zoonotic Pathogens


Human carriers are infected individuals who are ____________, but infective to others (as with AIDS and Syphilis)

Soil, Water, and Food

What are some examples of nonliving reservoirs?

Contact, Vehicle, and Vector Transmission

What are the 3 groups of infectious disease transmission?

Direct Contact Transmission

person-to-person spread by body contact between hosts (touching, kissing, and sexual intercourse)

Indirect Contact Transmission

Pathogens spread from host to host by Fomites -- contaminated inanimate objects (dishes, eating utensils, toys, toothbrushes, bedding, needles, medical equipment, etc.)

Droplet Transmission

Pathogens carried within Respiratory Droplets that exit the body with coughing, sneezing, and exhaling - but traveling less than 1 meter

Airborne Transmission

spread of Pathogens to respiratory mucous membranes via Aerosols (cloud of small droplets or solid particles suspended in the air) that travel more than 1 meter

Endemic Disease

a disease that occurs continually at a relatively stable incidence within a population or geographical area

Sporadic Disease

a disease with only a few scattered cases in a population or area


when a disease occurs at a greater frequency than usual in a population or area


Epidemic occurring simultaneously on more than one continent

Acute Disease

a disease that develops rapidly and lasts only a short time

Common cold

example of an acute disease

Chronic disease

a disease that develops slowly (usually with milder symptoms), but lasts a long time

Tuberculosis, Leprosy, Hepatitis C, and Infectious Mononucleosis

Give 4 examples (provided in the notes) of Chronic diseases

Subacute disease

a disease with a duration and severity between that of Acute and Chronic diseases

Subacute Bacterial Endocarditis

An example of a Subacute Disease

Latent Disease

a disease that appears a long time after the infection due to the inactivity of the Pathogen

Herpes Infection

give an example (provided in the notes) of a Latent Disease

Communicable Disease

a disease transmitted from an infected host directly or indirectly to another

Influenza, Tuberculosis, and Herpes Infection

Give 3 examples (provided in the notes) of Communicable diseases

Contagious disease

Communicable disease that is easily spread

Measles and Chickenpox

Give 2 examples of Contagious diseases

Noncommunicable disease

a disease NOT spread from host to host; it originates from outside of the host, or from an Opportunistic Pathogen within the host

Tetanus, Botulism, Acne, and Tooth Decay

Give 4 examples (provided in the notes) of Noncommunicable diseases

Local infection

an infection confined to a small area of the body

Focal infection

an infection that serves as a source of infection for other areas of the body

Primary infection

initial infection within the host

Secondary infection

an infection that follows the Primary infection, and may be caused by an Opportunistic Pathogen

Nosocomial infections

infections acquired while in a health care facility

Exogenous, Endogenous, and Iatrogenic

What are the 3 types of nosocomial infections?


type of nosocomial infection where the pathogen is acquired from the health care environment


type of nosocomial infection where the pathogen arises from Normal Microbiota due to factors within the health care setting (such as exposure to Chemotherapy)


type of nosocomial infection that results from modern medical procedures (use of Catheters, Invasive Diagnostic procedures, and Surgery)

Hand washing

What is the most effective way to reduce Nosocomial infections?

Staphylococcus, Streptococcus, and Hantaviruses

What 3 pathogens are transmitted through Airborne Transmission by being carried on dust particles?

See more

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording