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6.2.E: Innate Nonspecific Host Defenses (Exercises)

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    17.1: Physical Defenses

    Nonspecific innate immunity provides a first line of defense against infection by nonspecifically blocking entry of microbes and targeting them for destruction or removal from the body. The physical defenses of innate immunity include physical barriers, mechanical actions that remove microbes and debris, and the microbiome, which competes with and inhibits the growth of pathogens. The skin, mucous membranes, and endothelia throughout the body serve as physical barriers.

    Multiple Choice

    Which of the following best describes the innate nonspecific immune system?

    1. a targeted and highly specific response to a single pathogen or molecule
    2. a generalized and nonspecific set of defenses against a class or group of pathogens
    3. a set of barrier mechanisms that adapts to specific pathogens after repeated exposure
    4. the production of antibody molecules against pathogens
    Answer

    B

    Which of the following constantly sheds dead cells along with any microbes that may be attached to those cells?

    1. epidermis
    2. dermis
    3. hypodermis
    4. mucous membrane
    Answer

    A

    Which of the following uses a particularly dense suite of tight junctions to prevent microbes from entering the underlying tissue?

    1. the mucociliary escalator
    2. the epidermis
    3. the blood-brain barrier
    4. the urethra
    Answer

    C

    Fill in the Blank

    The muscular contraction of the intestines that results in movement of material through the digestive tract is called ________.

    Answer

    peristalsis

    ______ are the hair-like appendages of cells lining parts of the respiratory tract that sweep debris away from the lungs.

    Answer

    cilia

    Secretions that bathe and moisten the interior of the intestines are produced by _______ cells.

    Answer

    goblet

    Short Answer

    Differentiate a physical barrier from a mechanical removal mechanism and give an example of each.

    Identify some ways that pathogens can breach the physical barriers of the innate immune system.

    17.2: Chemical Defenses

    Numerous chemical mediators produced endogenously and exogenously exhibit nonspecific antimicrobial functions. Many chemical mediators are found in body fluids such as sebum, saliva, mucus, gastric and intestinal fluids, urine, tears, cerumen, and vaginal secretions. Antimicrobial peptides (AMPs) found on the skin and in other areas of the body are largely produced in response to the presence of pathogens. These include dermcidin, cathelicidin, defensins, histatins, and bacteriocins.

    Multiple Choice

    Which of the following serve as chemical signals between cells and stimulate a wide range of nonspecific defenses?

    1. cytokines
    2. antimicrobial peptides
    3. complement proteins
    4. antibodies
    Answer

    A

    Bacteriocins and defensins are types of which of the following?

    1. leukotrienes
    2. cytokines
    3. inflammation-eliciting mediators
    4. antimicrobial peptides
    Answer

    D

    Which of the following chemical mediators is secreted onto the surface of the skin?

    1. cerumen
    2. sebum
    3. gastric acid
    4. prostaglandin
    Answer

    B

    Identify the complement activation pathway that is triggered by the binding of an acute-phase protein to a pathogen.

    1. classical
    2. alternate
    3. lectin
    4. cathelicidin
    Answer

    C

    Histamine, leukotrienes, prostaglandins, and bradykinin are examples of which of the following?

    1. chemical mediators primarily found in the digestive system
    2. chemical mediators that promote inflammation
    3. antimicrobial peptides found on the skin
    4. complement proteins that form MACs
    Answer

    B

    Fill in the Blank

    ________ are antimicrobial peptides produced by members of the normal microbiota.

    Answer

    bacteriocins

    ________ is the fluid portion of a blood sample that has been drawn in the presence of an anticoagulant compound.

    Answer

    plasma

    The process by which cells are drawn or attracted to an area by a microbe invader is known as ________.

    Answer

    chemotaxis

    Short Answer

    Differentiate the main activation methods of the classic, alternative, and lectin complement cascades.

    What are the four protective outcomes of complement activation?

    17.3: Cellular Defenses

    The formed elements of the blood include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). Of these, leukocytes are primarily involved in the immune response. All formed elements originate in the bone marrow as stem cells (HSCs) that differentiate through hematopoiesis. Granulocytes are leukocytes characterized by a lobed nucleus and granules in the cytoplasm. These include neutrophils (PMNs), eosinophils, and basophils.

    Multiple Choice

    White blood cells are also referred to as which of the following?

    1. platelets
    2. erythrocytes
    3. leukocytes
    4. megakaryocytes
    Answer

    C

    Hematopoiesis occurs inwhich of the following?

    1. liver
    2. bone marrow
    3. kidneys
    4. central nervous system
    Answer

    B

    Granulocytes are which type of cell?

    1. lymphocyte
    2. erythrocyte
    3. megakaryocyte
    4. leukocyte
    Answer

    D

    Matching

    Match each cell type with its description.

    ___natural killer cell A. stains with basic dye methylene blue, has large amounts of histamine in granules, and facilitates allergic responses and inflammation
    ___basophil B. stains with acidic dye eosin, has histamine and major basic protein in granules, and facilitates responses to protozoa and helminths
    ___macrophage C. recognizes abnormal cells, binds to them, and releases perforin and granzyme molecules, which induce apoptosis
    ___eosinophil D. large agranular phagocyte that resides in tissues such as the brain and lungs
    Answer

    C, A, D, B

    Match each cellular defense with the infection it would most likely target.

    ___natural killer cell A. virus-infected cell
    ___neutrophil B. tapeworm in the intestines
    ___eosinophil C. bacteria in a skin lesion
    Answer

    A, C, B

    Fill in the Blank

    Platelets are also called ________.

    Answer

    thrombocytes

    The cell in the bone marrow that gives rise to all other blood cell types is the ________.

    Answer

    pluripotent hematopoietic stem cell (HSC)

    PMNs are another name for ________.

    Answer

    neutrophils

    Kupffer cells residing in the liver are a type of ________.

    Answer

    macrophage

    _____________ are similar to basophils, but reside in tissues rather than circulating in the blood.

    Answer

    mast cells

    Short Answer

    Explain the difference between plasma and the formed elements of the blood.

    List three ways that a neutrophil can destroy an infectious bacterium.

    Critical Thinking

    Neutrophils can sometimes kill human cells along with pathogens when they release the toxic contents of their granules into the surrounding tissue. Likewise, natural killer cells target human cells for destruction. Explain why it is advantageous for the immune system to have cells that can kill human cells as well as pathogens.

    Refer to Figure 17.3.2. In a blood smear taken from a healthy patient, which type of leukocyte would you expect to observe in the highest numbers?

    17.4: Pathogen Recognition and Phagocytosis

    Phagocytes are cells that recognize pathogens and destroy them through phagocytosis. Recognition often takes place by the use of phagocyte receptors that bind molecules commonly found on pathogens, known as pathogen-associated molecular patterns (PAMPs). The receptors that bind PAMPs are called pattern recognition receptors, or PRRs. Toll-like receptors (TLRs) are one type of PRR found on phagocytes.

    Multiple Choice

    PAMPs would be found on the surface of which of the following?

    1. pathogen
    2. phagocyte
    3. skin cell
    4. blood vessel wall
    Answer

    A

    ________ on phagocytes bind to PAMPs on bacteria, which triggers the uptake and destruction of the bacterial pathogens?

    1. PRRs
    2. AMPs
    3. PAMPs
    4. PMNs
    Answer

    A

    Which of the following best characterizes the mode of pathogen recognition for opsonin-dependent phagocytosis?

    1. Opsonins produced by a pathogen attract phagocytes through chemotaxis.
    2. A PAMP on the pathogen’s surface is recognized by a phagocyte’s toll-like receptors.
    3. A pathogen is first coated with a molecule such as a complement protein, which allows it to be recognized by phagocytes.
    4. A pathogen is coated with a molecule such as a complement protein that immediately lyses the cell.
    Answer

    C

    Fill in the Blank

    ________, also known as diapedesis, refers to the exit from the bloodstream of neutrophils and other circulating leukocytes.

    Answer

    extravasation

    Toll-like receptors are examples of ________.

    Answer

    pattern-recognition receptors (PRRs)

    Short Answer

    Briefly summarize the events leading up to and including the process of transendothelial migration.

    17.5: Inflammation and Fever

    Inflammation results from the collective response of chemical mediators and cellular defenses to an injury or infection. Acute inflammation is short lived and localized to the site of injury or infection. Chronic inflammation occurs when the inflammatory response is unsuccessful, and may result in the formation of granulomas (e.g., with tuberculosis) and scarring (e.g., with hepatitis C viral infections and liver cirrhosis).

    Multiple Choice

    Which refers to swelling as a result of inflammation?

    1. erythema
    2. edema
    3. granuloma
    4. vasodilation
    Answer

    B

    Which type of inflammation occurs at the site of an injury or infection?

    1. acute
    2. chronic
    3. endogenous
    4. exogenous
    Answer

    A

    Fill in the Blank

    A(n) ________ is a walled-off area of infected tissue that exhibits chronic inflammation.

    Answer

    granuloma

    The ________ is the part of the body responsible for regulating body temperature.

    Answer

    hypothalamus

    Heat and redness, or ________, occur when the small blood vessels in an inflamed area dilate (open up), bringing more blood much closer to the surface of the skin.

    Answer

    erythema

    Short Answer

    Differentiate exogenous and endogenous pyrogens, and provide an example of each.

    Critical Thinking

    If a gram-negative bacterial infection reaches the bloodstream, large quantities of LPS can be released into the blood, resulting in a syndrome called septic shock. Death due to septic shock is a real danger. The overwhelming immune and inflammatory responses that occur with septic shock can cause a perilous drop in blood pressure; intravascular blood clotting; development of thrombi and emboli that block blood vessels, leading to tissue death; failure of multiple organs; and death of the patient. Identify and characterize two to three therapies that might be useful in stopping the dangerous events and outcomes of septic shock once it has begun, given what you have learned about inflammation and innate immunity in this chapter.

    In Lubeck, Germany, in 1930, a group of 251 infants was accidentally administered a tainted vaccine for tuberculosis that contained live Mycobacterium tuberculosis. This vaccine was administered orally, directly exposing the infants to the deadly bacterium. Many of these infants contracted tuberculosis, and some died. However, 44 of the infants never contracted tuberculosis. Based on your knowledge of the innate immune system, what innate defenses might have inhibited M. tuberculosis enough to prevent these infants from contracting the disease?

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