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Which secretion is not a barrier that prevents pahogens from entering the body?
Antigens are foreign molecules that initiate an immune response
True or false? The leukocytes of the innate immune system are B cells, macrophages, and neutrophils
False. The leukocytes of the innate immune system are mast cells, macrophages, and neutrophils
How do cells involved in the innate immune response detect the presence of pathogens?
Leukocytes recognize unique molecules on pathogens. Pattern-recognition receptors on leukocytes recognize and bind to unique molecules on the pathogens, such as the amino acid N-formylmethionine in bacteria. This receptor binding leads to activation of the innate immune response
Which of the following cells can engulf a pathogen?
Macrophages. Macrophages are leukocytes that can engulf and digest a pathogen.
Which of the following statements best describes the role of mast cells in the inflammatory response?
They release chemicals that constrict blood vessels at the wound site. Mast cells release chemicals that constrict blood vessels at the wound site to decrease blood flow to the wound.
Which of the following events of the innate immune response occurs first when a wound that breaks the skin has occurred?
Platelets release proteins that form clots and decrease bleeding. The first response to broken skin is the release of clotting proteins from platelets in the bloodstream, which decreases bleeding and helps to seal the wound.
The site of inflammation may become swollen due to the increased numbers of cells and fluids at the site and painful due to signals from pain receptors.
True. The site of inflammation may also become red due to increased blood flow at the site; the inflammatory response continues until all invaders are eliminated and the wound is repaired.
Which structure is not a component of the adaptive immune system?
Tissues. Lymphocytes of the adaptive immune system do not travel to tissues.
True or false? B cells were originally isolated from the bursa in chickens, and their function is to produce antibodies; T cells were originally isolated from the thymus in mice, and their functions include killing host cells that are being infected with a virus.
Which of the following statements about the clonal-selection theory of immune system function is false?
A. Each lymphocyte recognizes one antigen.
B. Antigens are recognized by receptor proteins inside the lymphocyte.
C. An activated lymphocyte makes many copies of itself in response to an infection.
D. Cloned cells persist after the pathogen is eliminated.
Antigens are recognized by receptor proteins inside the lymphocyte.This statement is false; antigens are recognized by receptor proteins on the lymphocyte membrane.
What is the final step in the cell-mediated response to a viral infection?
Cytotoxic T lymphocytes punch holes in the membranes of infected host cells. This step causes infected host cells to disintegrate and prevents the virus from spreading to other cells.
How do cells involved in the humoral response respond to antigen presentation on the surface of a B cell?
Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies. Helper T cells recognize the receptor-antigen complex and activate the B cell, which divides and produces plasma and memory cells.
Which protein presents viral antigens on the outer surface of cells?
MHC protein. MHC proteins present antigens on the surface of infected host cells (cell-mediated response) or B cells (humoral response).
How are cytotoxic T lymphocytes (CTLs) produced?
CD8+ T cells divide and differentiate into cytotoxic T lymphocytes. CD8+ T cells divide and differentiate into a clone of cytotoxic T lymphocytes.
_____ interact with the antigen-class II MHC complex presented by macrophages.
Helper T cells. Specific helper T cells recognize specific antigen-class II MHC complexes. The result of this is an activated helper T cell that stimulates both humoral and cell-mediated immune responses.
B cells that have been stimulated by interleukin-2 develop into _____.
plasma cells. Plasma cells develop from B cells that have been stimulated by the interleukin-2 secreted by helper T cells.
The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response.
perforin ... cell-mediated. Perforin causes the lysis of pathogen-infected body cells; it is a component of the cell-mediated immune response.
Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____.
B cells ... plasma cells and memory cells. The antigen-selected proliferation of B cells produces clones of plasma cells and memory cells.
Which of these cells is responsible for the rapidity of the secondary immune response?
memory cells. Memory cells are responsible for the rapidity of the secondary immune response and for long-term immunity.
Which of these cells produce and secrete antibodies?
plasma cells Plasma cells are clones of antibody-secreting B cells.
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