EBK ANATOMY & PHYSIOLOGY
5th Edition
ISBN: 9780321888013
Author: Hoehn
Publisher: VST
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Chapter 20, Problem 20CYU
Describe the killing mechanism of cytotoxic T cells that involves perforins.
Figure 20.20 Simplified summary of the primary immune response.
Co-stimulation usually requires direct cell-cell interactions; cytokines enhance these and many other events. Although complement, NK cells, and phagocytes are innate defenses, they are enlisted in the fight by cytokines. (For simplicity, only B cell receptors are illustrated.)
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B cells express a complement receptor that binds to C3b cleavage products, such as iC3b and C3dg. When a B cell with an antigen receptor that specifically recognizes that pathogen also has its complement receptor stimulated because the pathogen is opsonized with these C3 fragments, B cell activation is greatly enhanced. Due to this mechanism, B cells can be activated by much lower concentrations of antigen (in this case, the pathogen) than if the antigen is devoid of complement components. This mechanism functions to:
Ensure that pathogens are readily detected by the adaptive immune system before they replicate to high levels in the host
Prevent B cells from being activated in response to antigens that are not pathogens
Allow B cells to phagocytose the pathogen and help destroy it
Induce increased rounds of B cell replication to make more pathogen-specific B cells
Allow the B cell to block pathogen replication by interfering with multiple pathogen surface functions
The diagram shows a pathogen (in red) that is present in different cellular compartments of each of the cell types shown. In each case, a specific T cell subset will recognize peptides of that pathogen presented on MHC molecules on the surface of the cell, and will execute its effector function. From the list below, match the appropriate T cell effector response to the cell type and location of the pathogen.
CD4 T cell killing of target cell
CD8 T cell killing of target cell
CD4 T cell activation of target cell’s antibody production
CD8 T cell activation of target cell’s antibody production
CD4 T cell activation of target cell’s ability to kill intracellular pathogen
CD8 T cell activation of target cell’s ability to kill intracellular pathogen
Which of the following statements is NOT correct?
Group of answer choices
-Natural killer cells are cytolytic lymphocytes that mediate ADCC
-Neutrophils carry out phagocytosis of C3b-tagged particles
-Macrophages carry out phagocytosis of C3b-tagged particles
-Mast cells produce granules containing the cytotoxin perforin
-B lymphocytes express a receptor for complement proteins
Chapter 20 Solutions
EBK ANATOMY & PHYSIOLOGY
Ch. 20 - What distinguishes the innate defense system from...Ch. 20 - What is the first line of defense against disease?Ch. 20 - What is opsonization and how does it help...Ch. 20 - Under what circumstances might NK cells kill our...Ch. 20 - What are the cardinal signs of inflammation and...Ch. 20 - Name three key characteristics of adaptive...Ch. 20 - What is the difference between a complete antigen...Ch. 20 - What marks a cell as self as opposed to nonselfCh. 20 - What event (or observation) signals that a B or T...Ch. 20 - Which of the following T cells would survive...
Ch. 20 - Prob. 11CYUCh. 20 - In clonal selection, who does the selecting? What...Ch. 20 - Why is the secondary response to an antigen so...Ch. 20 - Prob. 14CYUCh. 20 - Which class of antibody is most abundant in blood?...Ch. 20 - List four ways in which antibodies can bring about...Ch. 20 - Class II MHC proteins display what kind of...Ch. 20 - Prob. 18CYUCh. 20 - Which type of T cell is the most important in both...Ch. 20 - Describe the killing mechanism of cytotoxic T...Ch. 20 - Prob. 21CYUCh. 20 - Prob. 22CYUCh. 20 - Prob. 23CYUCh. 20 - All of the following are considered innate body...Ch. 20 - The process by which neutrophils squeeze through...Ch. 20 - Antibodies released by plasma cells are involved...Ch. 20 - Which of the following antibodies can fix...Ch. 20 - Which antibody class is abundant in body...Ch. 20 - Small molecules that must combine with large...Ch. 20 - Lymphocytes that develop immunocompetence in the...Ch. 20 - Cells that can directly attack target cells...Ch. 20 - Prob. 9RQCh. 20 - The cell type most often invaded by HIV is a(n)...Ch. 20 - Complement fixation promotes all of the following...Ch. 20 - Using the letters from column B, match the cell...Ch. 20 - Besides acting as mechanical barriers, the skin...Ch. 20 - Explain why attempts at phagocytosis are not...Ch. 20 - What is complement? How does it cause bacterial...Ch. 20 - Interferons are referred to as antiviral proteins....Ch. 20 - Differentiate between humoral and cellular...Ch. 20 - Although the adaptive immune system has two arms,...Ch. 20 - Define immunocompetence and self-tolerance. How is...Ch. 20 - Differentiate between a primary and a secondary...Ch. 20 - Prob. 21RQCh. 20 - What is the role of the variable regions of an...Ch. 20 - Name the five antibody classes and describe where...Ch. 20 - How do antibodies help defend the body?Ch. 20 - Do vaccines produce active or passive humoral...Ch. 20 - Prob. 26RQCh. 20 - Describe the specific roles of helper, regulatory,...Ch. 20 - Prob. 28RQCh. 20 - Prob. 29RQCh. 20 - What events can result in autoimmune disease?Ch. 20 - Prob. 1CCSCh. 20 - Prob. 2CCSCh. 20 - Prob. 3CCSCh. 20 - Prob. 4CCSCh. 20 - Prob. 5CCS
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- Figure 42.11 Which of the following statements about T cells is false? Helper T cells release cytokines while cytotoxic T cells kill the infected cell. Helper T cells are CD4+, while cytotoxic T cells are CD8+. MHC II is a receptor found on most body cells, while MHC I is a receptor found on immune cells only. The T cell receptor is found on both CD4+ and CD8+ T cells.arrow_forwardThe Adaptive Immune Response Is a Specific Defense Against Infection Name the class of molecules that includes antibodies, and name the five groups that make up this class.arrow_forwardCorrectly order the steps in cellular Immunity. Below is a sequence of events. Place them in the order they should occur, number 1 being the first item. Select the step number from the drop down next to each item. Items to order: a) .Cytotoxic T cell (CTL) recognizes the infected host cell b) The CTL secretes perforin and granzyme, causing apoptosis c) The CTL interacts with epitope presented by MHC-I on the dendritic cell d) The helper T cell activates the CTL cellarrow_forward
- Opsonization of pathogens by both antibodies and complement proteins (C3b) leads to uptake and destruction of the pathogen by phagocytic cells that express both Fc receptors and complement receptors. Which of the following in the figure below is the most efficient form of dual opsonization of the pathogen by antibody and C3b to maximize phagocytosis?arrow_forwardCompare and contrast humoral and cell-mediated immunity. Write three differences and two similarities in terms of function, purpose, types of cells involved, or mechanism. You may write in paragraph form or use a chart/diagram (e'g' Venn diagram) .arrow_forwardNeutralizing antibodies are effective at preventing infection or toxicity mediated by pathogens or their toxic products. In fact, nearly all vaccines currently in use function by eliciting neutralizing antibodies. One example is the tetanus vaccine, in which neutralizing antibodies are generated against an inactivated form of the tetanus toxin (the tetanus toxoid). The most important feature of a neutralizing antibody is having high affinity for the antigen. being efficient at activating the complement cascade. having a high degree of multivalency, such as being a pentamer or hexamer of immunoglobulin monomers. being present at a high concentration in the circulation. 0 0 0 0arrow_forward
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- Earlier it was stated that innate immunity employsprotective proteins, protective cells, and protectiveprocesses. Give three examples of eacharrow_forwardHelper T cells are affected by HIV, how come is this receptor key to the immune system? which line of defense are we referring to? How is it connected to the immune system and which line of defense? Hence, based on your prompt, how are cytokines linked to the defense mechanism of HIV virus? Do you know or can you explain the cascade of events dealing with PAMPS, TLRs, interferon? What do they have to do with the second line of defense?arrow_forwardWith the aid of a hand drawn diagram, briefly explain how T cells are primed or activated by B cells. In your response, briefly outline the major differences between B and T cell activationarrow_forward
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