micro Ch. 16 and 18

The chemical nature of endotoxins is that of a/an

lipopolysaccharide

People who carry and may spread pathogenic organisms without any apparent signs or symptoms of illness are called

carriers

Which of the following is NOT a likely reason why diseases caused by opportunists are becoming more frequent in the U.S. population?

Travel into and out of the U.S. has increased significantly. This has the potential to bring in many new pathogens that can cause infections, even in otherwise healthy and immunocompetent individuals.

A number of viruses often include a similar set of symptoms when they cause an infectious disease state (fever, headache, fatigue, runny nose). Why would they all cause the same symptoms if they're different viruses?

The symptoms are associated with the immune system's response, NOT the molecules from the pathogens themselves. Our responses against viruses are fairly similar, regardless of virus type, so the symptoms are similar.

The suffix -emia means in the

blood

The microorganisms that are occasionally found in or on the body are called

transient microbiota

Is it a good strategy for a microbe to adhere to a receptor that plays a critical function for a host cell?

Yes, it IS a good strategy. If it's a receptor the cell MUST use, it doesn't have an alternative receptor to switch to, so even though that receptor makes the cell susceptible to infection, it HAS to put that target out there. This benefits the microbe.

The damage caused by parasites may be due to all of the following EXCEPT

the parasite's immune response

A person's microbiome changes over time. Which of the following does not indicate such change?

Genera such as Firmicutes in the gut are only sometimes present

Please select the correct definition of balanced pathogenicity.

A host-parasite relationship in which the parasite persists in the host while causing minimal harm. The pathogen becomes less virulent while the host becomes less susceptible.

The chemical nature of exotoxins is that of a

protein

The series of steps used to connect an organism to a disease are known as

Koch's postulates

Attributes of an organism that promote pathogenicity are called

virulence factors

During incubation and convalescence a person may still spread infectious organisms.

True

Please select the CORRECT definition regarding interactions between hosts and microbes.

Dysbiosis—an imbalance in the microbiome that may be caused by taking antimicrobial medications.

Home-canned foods should be boiled before consumption to prevent botulism. Considering that this treatment does NOT destroy endospores, why would it be helpful in preventing the disease?

Because the heat would denature the botulism exotoxin and inactivate it. The exotoxin is what leads to the disease symptoms, so this would make the food safer.

A disease-causing microorganism or virus is referred to as a(n)

pathogen

The infectious dose

is defined as the number of microbes needed to cause infection

Select the correct sequence for proving Koch's postulates.

The microorganism must be recovered from the experimentally infected hosts.

The microorganism must be present in every case of the disease.

The same disease must be produced when a pure culture of the microorganism is introduced into susceptible hosts.

The microorganism must be grown in pure culture from diseased hosts.

2, 4, 3, 1

Colonization of the body is inhibited by

-peristalsis in the digestive tract.

-the shedding of skin cells.

-the movement of mucus by cilia.

-the flushing action of the urinary tract.

All of the answer choices are correct.

Virulent pathogens are

more likely to cause severe disease

Although the microbiome composition varies throughout a persn's lifetime, there are some genera that are constantly present in the microbiome.

True

Opportunists or opportunistic pathogens

take advantage of special circumstances

Which of the following factors is not considered important for the establishment of an infection?

Toxicity

If a disease affects only a human and not an animal, then it would be difficult to fulfill Koch's postulate number_________.

3

If the immune system responds inadequately to antigenic stimulation, this is termed

immunodeficiency

The fetus is not rejected because

it is in an immunologically privileged site

Select the INCORRECT statement regarding autoimmunity.

Graves' disease occurs when antibodies bind to receptors for thymus-stimulating hormone on the thymus gland resulting in inappropriate activation.

Graft-versus-host disease is primarily a

type IV reaction

Which of the following autoimmune diseases involve inappropriate binding of autoantibodies to receptors?

Graves' disease and myasthenia gravis

Immunosuppressive drugs

are needed indefinitely after transplantation.

Multiple myeloma is a plasma cell tumor in which a clone of malignant plasma cells produces large amounts of immunoglobulin. With all this excess immunoglobulin, how can a person with multiple myeloma be immunodeficient?

All the immunoglobulin produced is most likely specific to one antigen. This limits the ability to respond to the diversity of antigens we encounter AND the multiplication of the malignant plasma cells may crowd out normal production of other immune cells required for protective responses.

What is NOT a reason that the kidneys are particularly prone to damage caused by immune complexes?

Kidney blood vessel wall cells have receptors for antibodies on them, which makes them take up antibodies or immune complexes from the bloodstream. This blocks the kidneys up and causes them to malfunction and become damaged.

If a patient lacks B cells, the resulting disease is

agammaglobulinemia

Identify three physical responses of systemic anaphylaxis that can lead to rapid death.

-Constriction of bronchial tubes and suffocation.

-Blood vessel dilation resulting in low blood pressure.

-Insufficient blood flow to vital organs

Defects in bone marrow stem cells result in a condition known as

SCID

If the thymus fails to develop,

functional T cells are absent AND Di George's syndrome exists

Which of the following is the correct explanation of desensitization?

In desensitization, a person is injected with dilute preparations of an allergen, causing their immune system to produce IgG against that allergen. The IgG antibodies protect the patient by binding to the antigen, coating it and facilitating its removal before it can attach to bound IgE on mast cells or basophils.

In desensitization, a person is injected with dilute preparations of an allergen, causing their immune system to produce IgG against that allergen. The IgG antibodies protect the patient by binding to the antigen, coating it and facilitating its removal before it can attach to bound IgE on mast cells or basophils.

False

The hypersensitivity treatment that stimulates an increase of IgG and regulatory T cells, as well as causes a decrease in IgE, is known as

desensitization

Patch tests are used to detect

contact hypersensitivity

Which statement about primary immunodeficiencies that affect the complement system is INCORRECT?

People with defects in the complement system components acquire the condition from certain environmental influnces.

Mismatch of either the Rh antigen or the AB antigen results in lysis of red blood cells by complement.

True

Anti-A and anti-B antibodies are natural antibodies and are present at birth

False

MHC plays a pivotal role in transplant rejection

True

Regarding a mismatch of either the Rh antigen or the AB antigen, both

COME BACK TO THIS

If the thymus is removed from a 2-year-old child, which of the following is likely to occur?

Increased success of an organ transplant and increased incidence of bacterial infections.

The cell type responsible for type II hypersensitivity is the

B cell

Which autoimmune disease is CORRECTLY described?

Graves' disease—antibodies bind to the TSH receptor of the thyroid and activate it inappropriately, leading to increased thyroid hormone production and enlargement of the gland.

Select the incorrect pair regarding immunodeficiencies.

DiGeorge syndrome - inherited secondary immunodeficiency

Which of the following could be the result of an enterotoxin?

Vomiting and diarrhea

Which of the following is NOT a method by which pathogens penetrate a mucous membrane?

Through a bite wound or knife cut

Obligate intracellular parasites may be grown in special synthetic media.

False

The first step in the establishment of infection is that the organism must

attach to host cells

You have three patients: patient A has a deep cut on his arm, while patient B is complaining of diarrhea. Patient B is a smoker. Patient C has a respiratory viral infection. Pick the CORRECT statement regarding the risk of patients A and B to acquiring the respiratory virus from patient C.

Patient B is more at risk - being a smoker compromises the mucociliary escalator which protects the respiratory system.

The symbiotic relationship wherein both partners benefit is termed

mutualism.

Which of the following would be considered a sign of a disease?

A rash

Only Gram-positive bacteria produce exotoxins.

False

The most successful parasites are the ones that live in harmony with their hosts.

True

The period of time between exposure to an agent and the onset of disease signs and symptoms is called the

incubation period

Which person is LEAST at risk of acquiring a pathogen via the skin?

Person taking a recreational run

Disease(s) in which the causative agent becomes latent is/are

shingles, genital herpes, AND cold sores

A relationship in which one partner benefits and the other is harmed is termed

parasitism.

In two of Koch's postulates (#2 and #3), a pure culture of the organism is required. Which of the following would NOT be a possible consequence of using a contaminated culture?

Even though there's a contaminating microbe present, as long as the original suspect microbe is also present, the disease should still manifest in test animals and the organism should still be recoverable from test animals. As such, there's really no consequence to using a contaminated culture.

Newborn babies acquire microbiota

-from the environment.

-when passing through the birth canal.

-by contact with the mother's skin.

-through breastfeeding

All of the above are a source of microbiota.

Which of the following affect nervous system components and/or function?

Myasthenia gravis and multiple sclerosis

If the body recognizes parts of itself as being foreign, this is termed

autoimmune disease.

Anti-A and anti-B antibodies

are considered natural antibodies AND are typically IgM

Desensitization

stimulates an increase in IgG AND is a treatment for hypersensitivity reactions.

Which of the following genetic immunodeficiencies involve B cells?

Selective immunoglobulin A deficiency, agammaglobulinima and severe combined immunodeficiency

Why do Rh-negative but not Rh-positive mothers sometimes have babies with hemolytic disease of the newborn?

This disease results when an Rh-negative mother's immune system is primed to produce anti-Rh IgG antibodies that can cross the placenta. If the mother is Rh-positive, she won't produce any anti-Rh antibodies at all.

MHC plays a pivotal role in transplant rejection.

True

Cyclosporin A

is a relatively general immunosuppressant AND suppresses T-cell proliferation.

Allergic reactions occur only in people who are sensitized by prior exposure to a specific allergen. Identify the correct sequence of events that occur in a type I response.

The activated B cells proliferate into IgE-producing plasma cells and memory cells.

The Fc portion of the IgE binds to Fc receptors on either mast cells or basophils, so that the Fab sites of the antibodies can interact with a specific allergen.

Sensitization begins when the first contact with the allergen induces an antibody response—helper T cells activate naive B cells.

Cross-linking triggers the mast cell or basophil to undergo degranulation, a process that releases its inflammatory mediators.

On second exposure to the antigen, when adjacent IgE molecules on a mast cell or basophil bind to that antigen, the IgE molecules are cross-linked.

These inflammatory mediators can have a variety of effects associated with a type I allergy response.

3, 1, 2, 5, 4, 6

What is the correct sequence of events in the development of an IgE-mediated hypersensitivity?

Fc receptors on either mast cells or basophils bind to the Fc region of the IgE molecules.

Adjacent captured IgE antibodies are cross-linked, which causes the mast cells to degranulate.

Naive B cells contact the antigen and bind it, and are then activated by TH cells.

Inflammatory mediators cause allergy symptoms such as itchiness, and increased mucus production.

B cells proliferate, undergo class switching and begin producing IgE antibodies.

3, 5, 1, 2, 4

Why does a sensitized person not experience a skin reaction immediately after exposure to poison oak?

The reaction is caused by activation of memory T cells formed as a result of the first exposure. Active T cells are not formed immediately.

People with which of the following can generally mount an immune response to most pathogens except a few common microbes, including Staphylococcus aureus?

Primary immunodeficiency - defects in phagocytic cells

Antibodies that have arisen in the blood plasma without any obvious or deliberate stimulus are called

natural

Hemolytic disease of the newborn

may not manifest itself fully until after birth.

Which is not a treatment for autoimmune disease?

Prolonged course of multiple antibiotics.

Recombinant human monoclonal antibody (rhuMAb)

appears promising as a treatment for asthma AND uses an engineered form of an IgG molecule.

The natural antibodies in serum that react with A or B polysaccharide antigens are mostly of the class

IgM

Which of the following approaches is NOT used to treat autoimmune diseases?

Antibiotics and antiviral medications

The spread of toxin via circulation is called_________.

Toxemia

Membrane ruffling

is induced by some bacteria that trigger rearrangements of a cell's actin, leading to engulfment of those bacteria.

A strong attachment of a microorganism to a host cell automatically leads to disease.

False

How do cytomegaloviruses avoid the cellular immune response?

Their genome encodes "fake" MHC class I molecules. When these are produced, the virally infected cell is not a target for Tc cells or NK cells.

Which of the following cause a foodborne intoxication?

Staphylococcus aureus, E. coli O157:H7, AND Clostridium botulinum

Which of the following is/are true about endotoxins?

Lipid A is the toxic portion of the molecule

Which of the following is an example of damage caused by inflammation?

Glomerulonephritis - resulting from activation of complement system proteins.?

In order to colonize a host, a pathogen has to deal with the host's defenses. Which of the following is NOT a mechanism for doing this?

Producing lactoferrins for binding iron.

Which of the following does S. pneumoniae use to survive in the host?

Capsule

A more modern equivalent to Koch's postulates is termed

molecular postulates.

The interaction of all organisms within a biological community with their environment is called a(n)

ecosystem

Which of the following would NOT be considered virulence factor(s)?

Ribosomes

If a patient received a kidney transplant that was matched well across each of the major histocompatibility complex (MHC) molecules, but they stopped taking their anti-rejection drugs, what would happen and why?

The organ will be rejected, but it will be a gradual process since it was matched well. There are a number of other proteins that cannot be matched between donors, so the graft will still be viewed as "foreign" by the recipient's immune system, and will still be attacked and rejected.

Which of the following can be successfully treated with hormone injections?

Type I diabetes mellitus

Which of the following about immune complexes is FALSE?

They are involved in type II hypersensitivity reactions.

Urticaria is characterized by

wheal and flare

Which allergic condition is characterized by the formation of a wheal and flare?

Hives