W3extra Q 7 & A

Question 1

Which of the following is an example of a physical barrier?
Antibacterial fatty acids
Lysozymes in tears
Epithelial cells
Earwax

Answer 1

Epithelial cells form tight junctions that are a physical barrier to entry for organisms. Sebaceous glands in the skin secrete antibacterial and antifungal fatty acids. Earwax and lysozymes in tears are examples of biochemical secretions that trap potential disease-causing microorganisms.

Question 2

Which statement is true regarding the inflammatory response?
Inflammatory response is the third line of defense.
Inflammatory response relies on cellular components only.
Inflammatory response generates a nonspecific response.
Inflammatory response occurs in nonvascular tissue.

Answer 2

The inflammatory response is the second line of defense. It occurs at the site of tissue injury and generates a nonspecific response that involves cellular and chemical components. The inflammatory response occurs in tissues with a blood supply (vascularized).

Question 3

Which complement factor is considered an anaphylatoxin?
C3a
C1
C7
C9

Answer 3

C3a, C5a, and C4a are anaphylatoxins. They can induce the rapid degranulation of mast cells and the release of histamine.

Question 4

Which receptor is expressed on macrophages and facilitates recognition and phagocytosis of bacterial pathogens?
Complement receptors
Scavenger receptors
Toll-like receptors
Pattern recognition receptors

Answer 4

The scavenger receptors are primarily expressed on macrophages and facilitate recognition and phagocytosis of bacterial pathogens. Complement receptors recognize a variety of fragments produced through activation of the complement system. Toll-like receptors are expressed on the surface of cells, including epithelial, mast, neutrophils, macrophages, dendritic cells, and lymphocytes. They recognize pathogen-associated molecular patterns or stressed host cells. Pattern recognition receptors recognize patterns of infectious molecules. These receptors are found on cells involved in innate resistance.

Question 5

Which statement regarding mast cells is true?
Histamine causes vasoconstriction.

Mast cells are found only in blood vessels.

Snake bites, bee venoms, and toxins may cause activation.

Mast cells are not involved in allergic reactions.

Answer 5

ans: Snake bite/toxins

A number of things cause the activation of mast cells, including physical injury, chemical agents (including toxins, bee venom, and snake bites), immunologic means, and activation of an inflammatory response. Histamine is released from mast cells and causes vasodilation. Mast cells are found in loose connective tissue close to blood vessels. Mast cells are involved in initiating many allergic reactions.

Question 6

Which term describes an acidic sulfur-containing lipid that produces effects similar to histamine?
Leukotriene
Prostaglandin
Adhesion molecule
Phagocyte

Answer 6

Leukotrienes act similar to histamine and cause smooth muscle contraction, increased vascular permeability, and chemotaxis. Prostaglandins cause increased vascular permeability, chemotaxis, and pain. Adhesion molecules increase the stickiness between cells. Phagocyte cells ingest and dispose of foreign material.

Question 7

Which statement is true regarding neutrophils?
Neutrophils are agranular.
Neutrophils are the predominant phagocytes of early inflammation.
Neutrophils are the largest blood cells.
Neutrophils enter the site of injury after lymphocytes and macrophages.

Answer 7

Neutrophils are the predominant phagocytes of early inflammation. They arrive before lymphocytes and macrophages. Monocytes are the largest blood cells and are granular.

Question 8

What biochemical messenger is produced by macrophages and lymphocytes in response to a bacterial pathogen?
Interleukins Correct
Interferons
Chemokines
Tumor necrosis factor

Answer 8

Tumor necrosis factor
Interleukins are biochemical messengers produced by macrophages and lymphocytes in response to a bacterial pathogen. Interferons primarily protect against viral infections. Chemokines induce leukocyte chemotaxis. Tumor necrosis factor, produced by macrophages and lymphocytes, induces a multitude of proinflammatory effects including the enhancement of endothelial cell adhesion.

Question 9

Chronic inflammation is characterized by a(an)
lack of giant cells.
absence of exudate.
dense infiltrate of lymphocytes and macrophages. Correct
inflammation that lasts less than 2 weeks.

Answer 9

Chronic inflammation is characterized by a dense infiltrate of lymphocytes and macrophages. Giant cells are multinucleated cells that are formed by fused macrophages during granuloma formation. Chronic inflammation often results in pus formation, purulent discharge, and incomplete wound healing. Chronic inflammation of any cause lasts longer than 2 weeks.

Question 10

Which are not natural barriers?
Physical
Resistance Correct
Biochemical
Mechanical

Answer 10

Resistance is a means by which the body may avoid being infected, but it is not a natural barrier. The natural barriers include physical, biochemical, and mechanical, as well as inflammation at the body’s surfaces.

Question 11

Which characteristics are observable of vascular injury and inflammation? (Select all that apply.)
Redness
Coolness to the touch
Warmth to the touch
Increased swelling
Pain

Answer 11

The four characteristics that are observable for inflammation in vascular tissue are redness, heat, swelling, and pain.

Question 12

Which pathways activate the complement system? (Select all that apply.)
Antigen antibody
Classical
Lectin
Alternative

Answer 12

The complement system may be activated by the classical, lectin, and alternative pathways.

Question 13

Which functions of the clotting system are exhibited at the site of injury or inflammation? (Select all that apply.)

Prevents the spread of infection to adjacent tissues
Traps microorganisms at the site of inflammation for removal
Prevents clot formation at the site of injury
Provides a framework for future repair and healing

Answer 13

The clotting system exhibits the following functions: (1) prevents the spread of infection to adjacent tissues; (2) traps microorganisms and foreign bodies at the site of inflammation for removal by infiltrating cells such as neutrophils and macrophages; (3) forms a clot that stops bleeding; and (4) provides a framework for future repair and healing.

Question 14

Which are systemic effects of inflammation? (Select all that apply.)
Abscess formation
Fever
Leukocytosis
Increased levels of plasma proteins
Decreased levels of plasma proteins

Answer 14

The three primary systemic changes associated with an acute inflammatory response are fever, leukocytosis, and increased levels in circulating plasma proteins. Abscesses are a local manifestation of inflammation and are walled-off lesions filled with purulent exudates.

Question 15

A substance that is recognized as foreign or nonself is
immunoglobulins.
lymphocytes.
antibodies.
antigens.

Answer 15

Antigens are recognized as foreign and initiate the immune response. Immunoglobulins and antibodies are part of the adaptive immune response; they attack the antigen. Lymphocytes are a type of blood cell that is part of the adaptive response.

Question 16

Which statement is true regarding the immune response in humans?
Before birth, lymphocytes are not produced.
B lymphocytes come from the thymus.
The thymus releases mature lymphocytes.
Generation of clonal diversity occurs in primary lymphoid organs.

Answer 16

Generation of clonal diversity occurs in the primary lymphoid organs, which includes the thymus (T lymphocytes) and bone marrow (B lymphocytes). In the fetus, lymphocytes undergo extensive differentiation and proliferation that recognize almost any foreign antigen predominate. The thymus releases immature T cells that have the ability to recognize foreign antigens.

Question 17

Which statement best describes the cells and their functions in the humoral arm of the immune system?
Cells undergo differentiation and develop into subpopulations.
Cells attack cancerous cells.
Antibodies are primarily responsible for protection.
Cells in the humoral arm are also called cellular immunity.

Answer 17

Antibodies are primarily responsible for protection against viruses and bacteria and are part of the humoral arm of the immune system. The antibody can directly invade a microorganism or activate the immune response. T cells undergo differentiation, attack cancerous cells, and are part of cellular immunity.

Question 18

Which term describes the type of immunity that occurs when preformed antibodies are transferred from a donor to a recipient?
Passive
Active
Memory
Cellular

Answer 18

ans Passive
The two types of adaptive immunity are active and passive. Passive immunity occurs when preformed antibodies are transferred from a donor to a recipient. An example of passive immunity is the passage of maternal antibodies across the placenta to the fetus. Active immunity is produced by an individual after either a natural exposure or an immunization. Memory cells are formed through cellular and humoral immunity; they remember the antigen.

Question 19

What is the precise portion of the antigen that is configured for recognition and binding of an antibody?
Paratope
Epitope
Self-antigen
Immunogen

Answer 19

The antigenic determinant or epitope is the precise portion of the antigen that is configured for recognition and binding of an antibody. A paratope is the matching portion on the antibody or lymphocyte receptor. A self-antigen is one that is not foreign to the host. An immunogen is an antigen that induces an immune response.

Question 20

Which antigen is too small to initiate an immune response?
Carrier
Allergen
Hapten
Self-antigen

Answer 20

A hapten is a molecule that is foreign but too small to induce an immune response alone. However, when it binds to a larger carrier molecule, it is able to induce an immune response. An allergen is an antigen that can induce an allergic response. A self-antigen is not foreign but has the three other criteria to be an immunogen.

Question 21

It is true that immunoglobulin E (IgE) is

designed to protect the host from large viruses.

the primary cause of common allergies.

the only inflammatory cell that can damage a virus.

normally found at high concentrations in the circulation.

Answer 21

IgE, a mediator of common allergic responses,

is an antibody that is designed to protect the host from parasites and is the only inflammatory cell that can damage a parasite. IgE is normally found in low concentrations in the circulation.

Question 21

Which statement is true regarding immunoglobulin A (IgA) antibodies?
IgA-2 is predominantly found in blood.
IgA-1 is predominantly found in the body’s secretions.
The J chain anchors together the IgA molecules.
IgA is the most predominant immunoglobulin.

Answer 21

The J chain anchors together the IgA molecules to form dimers and helps them resist degradation from enzymes. IgA-1 is found in the blood, and IgA-2 is found in the secretions of the body. IgG is the most predominant immunoglobulin.

Question 22

Which criteria influence the degree of immunogenicity? (Select all that apply.)
Foreignness to the host
Appropriate size
Appropriate quantity
Chemical simplicity
Chemical complexity

Answer 22

The four criteria that influence the degree of immunogenicity are foreignness to the host, appropriate size, appropriate quantity, and adequate complexity.

Question 23

Which statement is true regarding aging and the immune system function?
Older adults have decreased circulating antibodies.
T-cell function is increased.
Antibody production to specific antigens is inferior.
Response to infection is rapid.

Answer 23

T-cell function is decreased, and immune responses are delayed. B-cell production is inferior; however, the cells have increased circulating antibody levels.

Question 23

Which are molecular classes of immunoglobulins? (Select all that apply.)
IgC
IgD
IgE
IgM
IgN

Answer 23

The five classes of immunoglobulin are IgG, IgA, IgM, IgD, and IgE.

Question 24

Which definition is true?
Allergy means the deleterious effects of hypersensitivity.
Immunity means an altered immunologic response.
Hypersensitivity means the protective response to an antigen.
Autoimmunity means the normal response to foreign antigens.

Answer 24

Allergy means the deleterious effects of hypersensitivity

to environmental antigens. Immunity is an organism’s ability to resist disease. Hypersensitivity is an altered immunologic response to an antigen that results in disease or damage to the host. Autoimmunity is a disturbance in the immunologic tolerance of self-antigens.

Question 25

Which statement is true regarding hypersensitivity reactions?
They require sensitization against a particular antigen.
They occur after the primary immune response.
Reactions are always delayed.
The most delayed reaction is anaphylaxis.

Answer 25

A hypersensitivity reaction requires sensitivity to an antigen and occurs after an adequate secondary immune response. These reactions may then be immediate or delayed. The most immediate reaction is anaphylaxis.

Question 26

Which statement best describes a type I reaction?
Most type I reactions are mediated by IgA.
Most type I reactions are allergic.
Most occur against medications.
Rarely does this type of reaction contribute to autoimmune diseases.

Answer 26

Most type I reactions are allergic. They are mediated by IgE. Most type I reactions occur against environmental antigens and can contribute to some autoimmune diseases.

Question 27

What antibody binds to a mast cell?
Cytotropic
Allergen
Antigen
Fc

Answer 27

A cytotropic antibody (also called a reagin) is the antibody that binds to the mast cell. An allergen is an environmental antigen that induces an allergic response. An antigen stimulates the immune response and antibody to bind to the mast cell. The Fc is the portion of the mast cell where IgE binds.

Question 28

Which statement is true regarding atopic individuals?
If one parent has allergies, then a 4% chance exists that the offspring will have similar allergies.
If two parents have allergies, then a 50% chance exists that their offspring will have similar allergies.
Atopic individuals tend to produce higher quantities of IgE.
No genes are associated with an atopic state.

Answer 28

Higher quantities of IgE are present in atopic individuals. If one parent has an allergy, then the individual has a 40% of having allergies; with two parents, the individual has an 80% of having allergies. Multiple genes have been associated with the atopic state.

Question 29

The Arthus reaction is an example of which type of sensitivity reaction?
I
II
III *
IV

Answer 29

Be nice to yourself :)

Question 29

Which statement is true of serum sickness?
Immune complexes are formed and deposited in target issues.
Immune complexes are formed and deposited in the blood vessels.
It is considered a Type II hypersensivity response.
Cytotoxic T lymphocytes are responsible for the condition.

Answer 29

Serum sickness reactions are caused by the formation of immune complexes in the blood and their deposition in target tissues. An Arthus reaction deposits complexes into the walls of blood vessels. Serum sickness is a Type III hypersensitivity reaction. Type IV mechanisms occur through either cytotoxic T lymphocytes or lymphokine-producing T-helper (Th) 1 cells.

Question 30

Which statement is true regarding a type IV allergic reaction?
Is immediate in its action
Is infiltrated with B cells
The reaction is mediated by antibody production.
Can be transferred by cells

Answer 30

Type IV hypersensitivity reactions can be transferred by cells but not by serum. Their actions are delayed because their onset takes from 24 to 72 hours. The site is infiltrated with T lymphocytes and macrophages. A clear hard center surrounds the erythema (redness).

Question 31

Which is an example of an alloimmune disease?
Tuberculin reaction
Graves disease
Contact dermatitis
Penicillin allergy

Answer 31

Graves disease is a classic autoimmune, or alloimmune, disease. Tuberculin reaction is a type IV reaction. Contact dermatitis is a type I reaction. Penicillin is an allergen that induces type I hypersensitivity.

Question 32

Which statement is true regarding unmatched packed red blood cell (RBC) transfusions?
Only three different RBC antigens have been identified.

Approximately 80 major carbohydrate antigens exist.

People with O type blood have neither A or B antigens.

A person with type A blood contains anti-O antibodies.

Answer 32

Type O blood does not contain type A or B antigens. However, 80 major different RBC antigens are present. A person with type A blood carries anti-B antibodies and a person with type B blood carries anti-A antibodies. Those with type O blood have anti-A and anti-B antibodies.

Question 33

Histamine release leads to which of the following? (Select all that apply.)
Bronchial smooth muscle contraction
Bronchoconstriction
Decreased vascular permeability
Vasoconstriction
Edema

Answer 33

Histamine contracts bronchial smooth muscle, which causes bronchoconstriction. Vascular permeability, edema, and vasodilation also increase.

Question 34

Which term describes an agent’s ability to produce disease?
Virulence
Pathogenicity
Infectivity
Immunogenicity

Answer 34

Pathogenicity is an agent’s ability to produce disease, and it depends on the speed of reproduction, the extent of tissue damage, and the production of toxins. Virulence is a pathogen’s capacity to cause severe disease. Infectivity is the pathogen’s ability to invade and multiply in the host. Immunogenicity is the ability of pathogens to induce an immune response.

Question 35

Which statement is true regarding bacteremia?
It occurs with a normal defense system of the body.
Gram-positive organisms typically cause bacteremia.
Endotoxins often cause symptoms such as vasodilation.
Symptoms include increased blood pressure.

Answer 35

Endotoxins are often produced by bacteria that grow in the blood. Common symptoms include vasodilation, hypotension (reduced blood pressure), and decreased oxygen delivery and can produce cardiovascular shock. Bacteremia is often caused by gram-negative bacteria and usually occurs with a failure of the body’s defense mechanisms.

Question 36

Which statement regarding viruses is true?
Viruses are less common than bacterial infections.
Viruses actively produce exotoxins.
Viruses bypass many defense mechanisms by developing intracellularly.
Viruses contain all their genetic information in ribonucleic acid (RNA).

Answer 36

Viruses enter the cell and may bypass many defense mechanisms. Viruses are the most common form of infection. They contain deoxyribonucleic acid (DNA) and RNA for their genetic information. They do not produce exotoxins or endotoxins.

Question 37

Which statement regarding fever is true?
Fever is a failure of the body to regulate temperature.
An endogenous pyrogen may produce fever.
The body’s central thermostat is the pituitary gland.
Fever is a failure of the body’s defense system.

Answer 37

A pyrogen is a substance that causes fever. Exogenous and endogenous pyrogens exist and affect the regulatory set point in the hypothalamus, which is the body’s thermostat. Fever is not a failure of the body’s defense system but may actually be beneficial. The body does not fail to regulate temperature; rather, the temperature is regulated at a higher level than normal with a fever.

Question 38

What contributes to antibiotic-resistant pathogens?
Inadequate sanitation
Genetic mutation
Loss of multidrug transporters
Limited use of antibiotics

Answer 38

Antibiotic resistance usually results from genetic mutations in the microorganism that can be directly transmitted to neighboring microorganisms. Sanitation and clean drinking water can help control infection. Multidrug transporters on the microorganism’s membrane affect the rate of intracellular accumulation of antibiotics by preventing entrance or increasing the efflux of the antibiotic into the cell. Overuse of antibiotics can lead to the destruction of the normal flora and selective overgrowth of antibiotic-resistant strains.

Question 39

When does secondary vaccine failure occur?
When toxoids are not administered
When bacteriophages are administered
When routine vaccinations are not administered
When booster immunizations are not administered

Answer 39

Secondary vaccine failure results if appropriate booster immunizations are not administered. Many adults vaccinated against diseases that are more severe in childhood will not get routine boosters. Although not developing debilitating illness, they may become asymptomatic carriers and infect unvaccinated children. Toxoids are purified toxins that have been chemically detoxified without loss of immunogenicity. Bacteriophages are viruses that specifically infect bacteria; these are used to treat antibiotic resistance.

Question 40

Which are the stages of pathologic infection? (Select all that apply.)3
Invasion
Death
Colonization
Metastasis
Multiplication

Answer 40

The stages of pathologic infection include colonization, invasion, spread, and multiplication. Death and metastasis are not stages of pathologic infection.

Question 41

Which are mechanisms of antigenic variation? (Select all that apply.)
Siderophoric switching
Mutation
Recombination
Gene switching

Answer 41

Mutation, recombination, and gene switching all are forms of antigenic variation. Siderophores are iron receptors on bacteria that assist in replication, and they have nothing to do with antigenic variation.

Question 42

Which mechanisms are used by viruses to evade the immune response? (Select all that apply.)
Rapid division
Antigenic specificity
Self-protein coat
Immune suppression
Lipopolysaccharide

Answer 42

Viruses have developed a number of ways to evade the immune system, including rapid division, the ability to survive inside a host cell, coating the viral capsid with self-antigens from the host cell, antigenic variation, neutralization of immune complexes, complement evasion, immune suppression, and tissue damage.

Question 43

Which demonstrates how antibiotic resistance may occur? (Select all that apply.)

Thickened bacterial cell walls trap the antibiotic.
Modification of the bacterial cell wall prevents antibiotic access.
Bacterial enzymes destroy the antibiotic.
Nucleus of the virus is destroyed.

Answer 43

Resistance may result from sequestration or decreased uptake of the antibiotic. Thickened cell walls or biofilms trap antibiotics in the extracellular matrix to prevent access to bacteria. Decreased uptake of the antibiotic results from modification of the cell wall. Bacterial enzymes can destroy the antibiotic. Antibiotics are given for bacterial infections, not viral.