CHAPTER 16 INNATE IMMUNITY
Place the following steps of phagocytosis in the order that they occur: 1. Endosome fuses with lysozome 2. Dendritic cell engulfs Rhinovirus 3. Epitopes are attached to MHC-II 4. Digestion of the Rhinovirus 5. MHC-II plus the attached epitope move to the outside of the dendritic cell
2,1,4,3,5 Dendritic cell engulfs Rhinovirus . Endosome fuses with lysozome Digestion of the Rhinovirus Epitopes are attached to MHC-II MHC-II plus the attached epitope move to the outside of the dendritic cell
Correctly order the steps involved cellular immunity: 1. The Tc recognizes the infected host cell 2. The Tc interacts with epitope presented by MHC-I on the dendritic cell 3. The Tc secretes perforin and granzyme, causing apoptosis 4. The helper T cell activates the Tc cell
2,4,1,3 The Tc interacts with epitope presented by MHC-I on the dendritic cell The helper T cell activates the Tc cell The Tc recognizes the infected host cell The Tc secretes perforin and granzyme, causing apoptosis
With respect to the membrane attack complex (MAC), which is most likely to occur once all of the C9 proteins insert into the bacterial plasma membrane?
A hole will form in the bacterium, allowing water to rush into the cell causing lysis.
Which of the following is NOT a step that ultimately leads to antibody production?
Activation of cytotoxic T cells by helper T cells
Which of the following statements is true?
Adaptive defenses include both humoral and cellular immunity.
In the Case of *Classical* *Activation*, Which Outcome Is Likely to Occur?Part complete Membrane attack complex will form. Inflammation will be stimulated. Pathogens will become opsonized. All of the listed outcomes will occur.
All of the listed outcomes will occur.
Which of the complement pathways employs properdin?
Alternative pathway
What is meant by the *clonal* *expansion* of a B cell?
An activated B cell divides into cells that give rise to memory B cells and plasma cells
A response that is uniquely directed against pathogenic Bordetella pertussis would involve what component?
Antibodies
Third Line of defense
B Lymp T Lymp
Which pair of molecules do NOT directly interact with one another?
BCR and TCR
Which of the following statements concerning phagocytosis is true?
Bacteria are digested when the phagosome fuses with a lysosome.
Based on the animation, which of the following is cleaved by C1?
C2 and C4
Based on the animation, which of the following is responsible for cleaving C3?
C2aC4b
A microbe has the ability to inhibit complement activation of inflammation, but it cannot inhibit complement activation of opsonization and cytolysis. Therefore, the microbe has produced inhibitors of which complement protein(s)?
C3a and C5a
In the classical pathway, which of the following directly activates cellular responses?
C3a, C5a, and C5bC6C7
Based on the animation, which of the complement proteins can directly bind to the surface of a bacterial cell?
C3b
Which complement protein is used as an opsonin?
C3b
The absence of C5 means that the molecule is not present to be activated. What happens in normal serum when C5 is "activated?
C3b is a part of enzyme that splits C5 into two fragments, C5a and C5b. This happens in the three complement activation pathways. C3b is a part of an enzyme that digests C5.
Fragment C5b initiates the binding of the terminal complement proteins that form the membrane-attack complex (MAC). Which of these proteins associates with the MAC?
C7 The sequence of assembly is C6, C7, and C8. C8 then recruits multiple C9 proteins that assemble into a pore in the membrane.
Which of the following is an INCORRECT statement about antimicrobial peptides (AMPs)?
CORRECT ANSWER: AMPs have a narrow spectrum of antimicrobial activities. The following is an INCORRECT statement about antimicrobial peptides: AMPs have a narrow spectrum of antimicrobial activities. AMPs do not have a narrow spectrum; they have a broad spectrum of antimicrobial activities, including activity against bacteria, viruses, fungi, and eukaryotic parasites.
Which of these molecules or structures is/are NOT associated with innate immunity?
CORRECT ANSWER: Antibodies Antibodies are NOT associated with innate immunity. Innate immunity refers to defenses that are present at birth. They are always available to provide rapid responses to protect us against disease. Innate immunity does not involve recognition of a specific microbe. Further, innate immunity has no memory response, that is, a more rapid and stronger immune reaction to the same microbe at a later date.
Which term best describes the symbiotic relationship between humans and most of the normal microbiota that live on our human skin?
CORRECT ANSWER: Commensalism Commensalism would best describe the symbiotic relationship between humans and most of the normal microbiota that live on our human skin. In commensalism, one organism uses the body of a larger organism as its physical environment and may make use of the body to obtain nutrients. Thus in commensalism, one organism benefits while the other is unaffected.
Which of the following is NOT a chemical factor that helps the skin to be relatively resistant to infection?
CORRECT ANSWER: Complement proteins Complement proteins are NOT a chemical factor that helps the skin to be relatively resistant to infection. The complement system consists of over 30 proteins produced by the liver that circulate in blood serum and within tissues throughout the body
Which of the following statements concerning lysozyme is FALSE?
CORRECT ANSWER: It is an organelle in white blood cells Lysozyme is an enzyme capable of breaking down cell walls of gram-positive bacteria and, to a lesser extent, gram-negative bacteria. Specifically, lysozyme breaks chemical bonds on peptidoglycan.
Which of the following does NOT accurately describe innate immunity?
CORRECT ANSWER: It produces strong, long-lasting memory responses. The following does NOT accurately describe innate immunity: It produces strong, long-lasting memory responses. Innate immunity refers to defenses that are present at birth. They are always available to provide rapid responses to protect us against disease. Innate immunity does not involve recognition of a specific microbe. Further, innate immunity has NO memory response, that is, a more rapid and stronger immune reaction to the same microbe at a later date.
Which type of leukocyte is the most abundant in blood?
CORRECT ANSWER: Neutrophils Neutrophils are the most abundant leukocyte in the blood. It makes up about 60 to 70% of the formed elements.
__________ are involved in detecting foreign invaders. They do so by binding to pathogen- associated molecular patterns (PAMPs) on the surface of the pathogen.
CORRECT ANSWER: Toll-like receptors Responses of the innate system are activated by protein receptors in the plasma membranes of defensive cells. Among these activators are Toll-like receptors (TLRs). These TLRs attach to various components commonly found on pathogens that are called pathogen-associated molecular patterns (PAMPs).
Which of the following is the correct order of events after tissue damage during the process of inflammation?
CORRECT ANSWER: Vasodilation; margination; diapedesis; phagocytosis The correct order of events after tissue damage during the process of inflammation is: vasodilation; margination; diapedesis; phagocytosis. After tissue repair, vasodilation and increased permeability of blood vessels allows phagocyte migration. The phagocytes stick to endothelium (margination), phagocytes squeeze between endothelial cells (diapedesis), and phagocytosis of invading bacteria occurs.
Neutrophils, basophils, and eosinophils are collectively referred to as __________.
CORRECT ANSWER: granulocytes Granulocytes owe their name to the presence of large granules in their cytoplasm that can be seen with a light microscope after staining. They are differentiated into three types of cells based on how the granules stain: neutrophils, basophils, and eosinophils.
Which of these cells do NOT have phagocytic activity?
CORRECT ANSWER: lymphocytes Lymphocytes are NOT phagocytic. Eosinophils, macrophages, and neutrophils have phagocytic activity.
The ID50 for many pathogens is significantly smaller when testing with gnotobiotic animals compared to animals with normal microbiota. This is likely because of __________.
CORRECT ANSWER: microbial antagonism Microbial antagonism, the normal microbiota prevent pathogens from colonizing the host by competing with them for nutrients (competitive exclusion), by producing substances that are harmful to the pathogens, and by altering conditions that affect the survival of the pathogens, such as pH and oxygen availability. A gnotobiotic animal only harbors none or only a few known bacterial strains which does not provide protection and is thus known as microbial antagonism.
When blood cells are removed from blood, the remaining liquid is referred to as __________.
CORRECT ANSWER: serum Serum is the straw-colored liquid remaining after blood is allowed to clot. Red blood cells are a type of cell. leukocytes are white blood cells, leukocytic fluid is not a term. The buffy coat is a thin layer of concentrated white blood cells that forms when a tube of blood is spun in a centrifuge.
The respiratory system is protected against harmful microbes by all of the following EXCEPT __________.
CORRECT ANSWER: the lacrimal apparatus The respiratory system is protected against harmful microbes by all EXCEPT the lacrimal apparatus. One mechanism that protects eyes, not the respiratory system, is the lacrimal apparatus, a group of structures that manufactures and drains tears.
Which of the following can release histamines?
Cells from damaged tissues and the complement pathway
What complement result involves the use of phagocytes?
Chemotaxis and opsonization
A person who has AIDS contracts rare and often life-threatening infections because their helper T cell count is so low. Which of the following components of the immune response still respond to antigen despite the low helper T cell count?
Clonal selection of B cells B cells can still bind to antigen, which is the process of clonal selection. However, without a helper T cell, clonal expansion and antibody production will not occur.
Which microorganism requires the low pH inside a phagolysosome in order to reproduce?
Coxiella burnetii
If a person could not form C2, which result of complement would be affected?
Cytolysis, chemotaxis, inflammation, and opsonization
Pus is comprised of
Dead phagocytes.
Second line of defense
Fever NK cells
How does cytolysis occur via the complement pathway?
Formation of the MAC in invading cells, killing them
What does the plasma membrane of a phagocyte attach to on a microorganism?
Glycoproteins
What is the role of helper T cells in the adaptive immune response?
Helper T cells activate B cells and cytotoxic T lymphocytes to kill infected host cells.
Which of the following statements about innate immunity is true?
Innate immunity is present at birth.
Which of the following is an event that ultimately results in activation of complement C3 by splitting it into C3a and C3b?
Interaction of mannose-binding lectin with mannose molecules on a bacterium
Which of the following statements about beta interferons is true?
It acts as a signal that induces uninfected cells to produce antiviral proteins.
Why is vasodilation important to tissue repair?
It allows for an increased delivery of oxygen, nutrients, and phagocytes to the site of damage.
An inflammatory response would result from which of the following?
Jellyfish sting
__________ is/are always present in an individual's blood. However, in the absence of infection, it is in an inactive form.
Kinins
Direct cell lysis
MAC introduces holes to the bacterial cell membrane. Multiple transmembrane proteins are recruited to the pathogen. C9 is polymerized into a circular-shaped complex on the pathogen surface.
Opsonization
Macrophages and neutrophils are attracted to C3 protein molecules bound to the pathogens, making them easier to phagocytize. C3b fragments bind to the surface of pathogens.
. Why are memory cells an important product of an immune response?
Memory cells allow subsequent immune responses against the same antigen to occur more strongly and more quickly.
Inflammation stimulation
Neutrophils are attracted to the area and arrive via diapedesis. C5a fragments recruit immune cells to the site of infection. C3a fragments act as chemotactic agents.
If a person lacked the ability to form C5, what direct result of complement could still occur?
Opsonization
Which of the following cell types is NOT part of the second line of defense? mast cells eosinophils basophils plasma cells
PLASMA CELLS
Suppose that Charlie and Rachelle have a C3 deficiency rather than a C5 deficiency. What would be one consequence for innate immunity to microbes if these siblings lack C3 in their blood?
Phagocytes could not attach as easily to invading microbes. C3b is an important opsonin.
What cellular macromolecules make up the complement pathway?
Proteins
How is phagocytosis in the immune system different from protozoan phagocytosis?
Protozoan phagocytosis is used for feeding; phagocytosis by immune cells is used to fight infection.
Which of the following is NOT a step used by cytotoxic T cells to kill infected host cells?
Recognition of infected host cell using its CD4 glycoprotein The cytotoxic T cell uses its *CD8* glycoprotein to bind to the MHC-I of an infected host cell.
Which of the following microorganisms use M protein to avoid destruction of a phagocyte?
Streptococcus pyogenes
Fist Line of defense
Sweat Sebum (oil)
If a person turns their ankle, how would one determine if damage to the tissue in the ankle has occurred?
The ankle is red, swollen, and warm to the touch.
Where are the complement proteins found in the body?
The blood serum
Which of the complement pathways was discovered first?
The classical pathway
What is a phagolysosome?
The structure that results from the fusion of a phagosome and a lysosome
How is Streptococcus pneumoniae able to avoid destruction by a phagocyte?
Their capsules make them "slippery" to phagocytes.
Which of the following are functions of lectins?
They act as opsonins for phagocytosis, they attach to carbohydrates on some bacterial and viral surfaces, and they activate C2 and C4.
What direct effect do histamines and leukotrienes have on capillaries?
They allow capillary walls to open and become leaky.
First line defenses have what aspect in common with each other?
They are physical barriers against invading pathogens.
What is the role of opsonins?
They create "handles" that make it easier for the pseudopods of phagocytes to attach to the microbe invader.
Alternative pathway
This pathway involves factors B, D, and F binding to pathogen.
Lectin pathway
This pathway involves secretion of waste products by phagocytes. This pathway involves phagocytes engulfing pathogens.
Classical pathway
This pathway requires C1 to become activated. This pathway requires antibody-antigen complex. This pathway requires previous activation of the adaptive immune response.
What is the function of inflammation in response to a burn from a hot iron?
To repair the damaged tissue
If a new bacterial pathogen entered a human body through an accidental needle stick, the first cell that would try to kill the pathogen would likely be
a phagocyte
Immunity
ability to ward off disease
All of the following pertain to fever EXCEPT that it intensifies the effect of antiviral interferons. stimulates T lymphocyte activity. is caused by interleukin-1 and TNF-alpha coming into contact with the hypothalamus. accelerates microbial growth by increasing iron absorption from the digestive tract. can be initiated by specific types of pathogens
accelerates microbial growth by increasing iron absorption from the digestive tract.
Activation of C3 results in __________. enhancement of phagocytosis via opsonization formation of a membrane attack complex (MAC), which causes cytolysis of bacteria release of histamine and other pro-inflammatory chemicals all of the listed choices
all of the listed choices
The classical pathway of complement activation begins with binding of __________.
an antibody The *classical* *pathway* of complement activation begins with an *antibody* binding to an *antigen* on the microbe's surface
Which of the following are best described as short chains of amino acids that are very stable and can have a variety of different antimicrobial activities, such as forming pores in bacterial plasma membranes and inhibiting cell wall synthesis?
antimicrobial peptides
The process by which a phagocyte moves toward a chemical signal at the site of an infection is called
chemotaxis
The epidermis __________.
contains the protein keratin The epidermis contains the protein keratin. The epidermis, the outer, thinner portion, is in direct contact with the external environment. The epidermis consists of many layers of continuous sheets of tightly packed epithelial cells with little or no material between the cells. The top layer of epidermal cells is dead and contains a protective protein called keratin.
Innate immunity
defenses against any pathogen; rapid, present at birth
You note that the body temperature of one of your patients is starting to increase. As a result, you can infer that all of the following may be occurring in this patient EXCEPT __________. constriction of blood vessels dilation of blood vessels increased metabolic rate shivering
dilation of blood vessels
One remarkable finding on a patient's laboratory workup is a marked eosinophilia. This might be suggestive of __________.
either a parasitic infection or an allergic (hypersensitivity) reaction Eosinophilia is suggestive of either a parasitic infection or an allergic (hypersensitivity) reaction. Eosinophilia is a marked increase in the numbers of eosinophils in the blood. Their major function is to produce toxic proteins against certain parasites, such as helminths. Although eosinophils are physically too small to ingest and destroy helminths, they can attach to the outer surface of the parasites and discharge peroxide ions that destroy them. Their number increases significantly during certain parasitic worm infections and hypersensitivity (allergy) reactions.
If one is examining a blood smear from a patient with a parasitic worm infection, which of the following leukocytes would be found in increased numbers?
eosinophils
Which of the following phagocytic processes occurs last in the sequence?
exocytosis
Adaptive immunity
immunity or resistance to a specific pathogen; slower to respond, has memory component
The antimicrobial effects of AMPs include all of the following EXCEPT destruction of nucleic acids. lysis of bacterial cells. inhibition of phagocytosis. inhibition of cell wall synthesis. pore formation in bacterial membranes.
inhibition of phagocytosis.
Which group contains *ONLY* innate physical defenses?
intact skin, tears, ciliary escalator
Susceptibility
lack of resistance to a disease
Because C5 is absent in their sera, which of the protective effects of complement activation does not occur in response to infection with Neisseria meningitidis?
lysis of infecting microbes Anchored in a microbial membrane, C5b serves as the binding site for the complement proteins that form the membrane-attack complex.
Which non-specific defense mechanism is mismatched with its associated body structure or body fluid?
mucociliary escalator intestines
Toll-like receptors (TLRs) on host cells attach to ____?
pathogen-associated molecular patterns (PAMPs) TLRs bound to *PAMPs* induce the release of *cytokines* from the host cell that regulate the intensity and duration of immune responses
Which of the following represents the first line of defense?
skin and mucous membranes
Antibodies from cellular immune responses are used in
the classical pathway
Phagocytosis is defined as
the ingestion of solid material by a eukaryotic cell.
EMIGRATION IS
the migration of phagocytes through blood vessels to the site of tissue damage.
Both the innate and adaptive defenses of the immune system work to prevent
the penetration and colonization by pathogens, and the diseases they cause.