According to the animation, B cells interact directly with?
answer
helper T cells
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Which of the following defense systems would be involved in eliminating virally-infected cells?
answer
T lymphocytes
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According to the animation, antibodies interact with which innate defenses?
answer
Phagocytosis and the complement system
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Which cells directly attack abnormal cells in the body?
answer
Cytotoxic T cells
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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 (as opposed to a blood smear from a normal patient NOT infected with worms)?
answer
eosinophils
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What direct effect do histamines and leukotrienes have to capillaries?
answer
They allow capillary walls to open and become leaky
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Diapedesis is?
answer
the migration of phagocytes through blood vessels to the site of tissue damage
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Why is vasodilation important to tissue repair?
answer
It allows for an increased delivery of oxygen, nutrients, and phagocytes to the site of damage
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Pus is comprised of?
answer
dead phagocytes
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Which of the following can release histamines?
answer
Cells from damaged tissues and the complement pathway
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Which of the complement pathways employs properdin?
answer
Alternative pathway
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In the classical pathway, which of the following directly activates cellular responses?
answer
C3a, C5a, and C5bC6C7
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Antibodies from cellular immune responses are used in?
answer
the classical pathway
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Which of the complement pathways was discovered first?
answer
The classical pathway
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Which of the following are functions of lectins?
answer
They act as opsonins for phagocytosis, they attach to carbohydrates on some bacterial and viral surfaces, and they activate C2 and C4
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How does cytolysis occur via the complement pathway?
answer
Formation of the MAC in invading cells, killing them.
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Which complement protein is used as a opsonin?
answer
C3b
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If a person lacked the ability to form C5, what direct result of complement could still occur?
answer
Opsonization
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If a person could not form C2, which result of complement would be affected?
answer
Cytolysis, chemotaxis, inflammation, and opsonization
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What complement result involves the use of phagocytes?
answer
Chemotaxis and opsonization
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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?
answer
antimicrobial peptides
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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 the patient EXCEPT?
answer
dilation of blood vessels
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Which of the following statements about innate immunity is true?
answer
Innate immunity is present at birth
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Which of the following statements concerning phagocytosis is true?
answer
Bacteria are digested when the phagosome fuses with the lysosome
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A child falls and suffers a deep cut on her leg. The cut went through her skin and she is bleeding. Which of the following defense mechanisms will participate in eliminating contaminating microbes?
answer
phagocytosis in the inflammatory response
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What is the role of the helper T cell in the adaptive immune response?
answer
Helper T cells activate B cells and cytotoxic T lymphocytes to kill infected host cells
Hint: Remember that Helper T cells are called "helpers" because they coordinate the overall immune response without actively fighting the infection themselves.
Hint: Helper T cells activate B cells that are displaying antigen, causing clonal expansion. Helper T cells also activate cytotoxic T cells, which will search for and destroy infected host cells.
question
What is meant by the clonal expansion of a B cell?
answer
An activated B cell divides into cells that give rise to memory B cells and plasma cells.
Hint: "Clonal" refers to the production of genetically identical cells. Thus, clonal expansion is when one cell creates many genetically-identical cells, each of which can differentiate to have different functions.
Hint: The activated B cell divides until there are many clones. Some differentiate into memory cells, others become plasma cells that produce and secrete antibodies.
question
The student who caught the cold caused by this specific Rhinovirus was exposed to the exact same Rhinovirus 18 months later. What component of the immune system will protect her from getting the same cold again?
answer
Memory B cells
Hint: Reexposure to a virus
within a few weeks or months, active adaptive immunity wanes, returning to near pre-infection levels. With no active antibody secretion, and the "old" antibodies disappearing, what could protect this student during the second viral attack?
Hint: Memory cells to the specific virus are stored in the lymph nodes for many years. When the student comes into contact with this specific Rhinovirus, these memory cells quickly divide and differentiate into antibody-producing plasma cells. The antibodies will prevent the virus from reaching an infectious titer (number that causes infection).
question
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
answer
2,4,1,3
Hint: Tc cells require 2 signals before it is able to kill infected cells. First, it must bind with high specificity to an antigen presented by an antigen-presenting cell. Second, it must detect a helper T cell's cytokines, indicating that there is danger in the area.
question
Which of the following is NOT a step used by cytotoxic T cells to kill infected host cells?
answer
Recognition of infected host cell using its CD4 glycoprotein
Hint: Tc vs. Th cells
Tc and Th cells follow a similar path upon identification of a foreign epitope. Which of the answers is NOT specific to a Tc cell?
Hint: The cytotoxic T cell uses its CD8 glycoprotein to bind to the MHC-I of an infected host cell
question
Place the following steps of phagocytosis in the order that they occur:
1. Endosome fuses with lysozome
2. Dendritic cells 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
answer
2, 1, 4, 3, 5
Hint: Digestion of the Rhinovirus is critical. It is degraded intracellularly in lysosomes. The degradation breaks its proteins into small peptides which can be loaded into MHC molecules for presentation.
question
Which pair of molecules do NOT directly interact with one another?
answer
BCR and TCR
Hint: CD4, CD8, BCR and TCR are all receptors on the cell surface, each binding to a specific molecule
Hint: Both of these molecules interact with epitopes. BCRs interact with epitopes on the whole pathogen. TCRs interact with processed epitopes when presented on MHC-II
question
Which of the following is NOT a step that ultimately leads to antibody production?
answer
Activation of cytotoxic T cells by helper T cells
Hint: Humoral immunity involves the production of antibodies. One of the answers refers to cell-mediated immunity instead.
Hint: The activation of cytotoxic T cells leads down the path of cell-mediated immunity
question
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?
answer
Clonal selection of B cells
Hint: Helper T cells coordinate the overall adaptive immune response. However, they do not play a major role until after the naive lymphocyte has recognized its specific target and the lymphocyte has differentiated
Hint: 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
question
Which of the following statements is true?
answer
Adaptive defenses include both humoral and cellular immunity
Hint: Humans have evolved to require both innate and adaptive defenses to survive. The former refers to physical barriers, phagocytes, complement, etc., while the latter refers to antibody production, cytokine production, and cell-mediated apoptosis
Hint: Adaptive defenses are operating optimally when both humoral and cellular immunity are working together in response to a pathogen
question
Mycobacterium tuberculosis is an intracellular pathogen of humans. After being ingested by a macrophage, it prevents formation of the _____ by preventing fusion of the phagosome with the ________
answer
Phagolysosome, lysosome
Hint: As a phagosome "matures", it acquires a variety of degradative enzymes and the pH of the inside of the phagosome decreases. Which organelle is acidic and contains degradative enzymes?
question
In which intracellular compartment would you expect most of the digestive enzymes involved in pathogen destruction to be found?
answer
lysosome
Hint: As a phagosome "matures", it acquires a variety of degradative enzymes and the pH of the inside of the phagosome decreases. Which organelle is acidic and contains degradative enzymes?
question
In macrophages and dendritic cells (so-called antigen-presenting cells) some small part of the phagocytosed particle are presented to other cells of the immune system. If you were to draw an arrow leading to "antigen presentation" as described above, from which word would it extend?
answer
digestion
Hint: For an antigen to be presented to MHC-II, it must be broken down into a peptide of the appropriate size.
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Which type of cell matures to form a macrophage?
answer
monocytes
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What is the term for the widening of blood vessels?
answer
vasodilation
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What type of immunity targets specific microbes?
answer
adaptive immunity
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Which of these is an example of a first line defense?
answer
the ciliary escalator
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What is the term for the movement of phagocytes through a blood capillary wall to the site of infection?
answer
emigration (aka diapedesis)
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Which of these proteins gives strength and toughness to epidermal tissue?
answer
keratin
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Which of these is the general term for all white blood cells?
answer
lymphocyte
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Which of these events happens first in phagocytosis?
answer
chemotaxis
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What encloses a microbe inside a phagocytic cell?
answer
phagosome
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True or False
Capsules and cell wall proteins allow some bacteria to evade the adherence steps of phagocytosis?
answer
True
question
True or False
The symptoms of inflammation include redness, heat, swelling, and pain?
answer
True
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Which type of white blood cell is capable of phagocytosis?
answer
neutrophil
question
What step of phagocytosis is improved by opsonization?
answer
adherence
question
Which of these molecules are produced in response to vital infections?
A) prostaglandins
B) interferons
answer
Prostaglandins
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The most abundant white blood cells found in the blood is the _______.
answer
neutrophil
question
What are the five types of white blood cells? List them by relative abundance in the bloodstream
