BSC2010 Chapter 43 The Immune System

Select the pathway that would lead to the activation of cytotoxic T cells. A. body cell becomes infected with a virus → new viral proteins appear → class I MHC molecule-antigen complex displayed on cell surface B. cytotoxic T cells → class II MHC molecule-antigen complex displayed → cytokines released → cell lysis C. complement is secreted → B cell contacts antigen → helper T cell activated → cytokines released D. B cell contact antigen → helper T cell is activated → clonal selection occurs

. body cell becomes infected with a virus → new viral proteins appear → class I MHC molecule-antigen complex displayed on cell surface

How is a viral antigen, like EBV, recognized by T cells?

An antigen fragment is presented within class I MHC to the T cell receptor.

How does an antihistamine reduce allergy symptoms?

An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells. Allergens attach to the antigen-binding sites of these IgE antibodies. This attachment links adjacent IgE molecules, inducing the mast cell to release histamine and other inflammatory chemicals from granules. Antihistamines diminish allergy symptoms (and inflammation) by blocking receptors for histamine. Read about allergies.

Which secretion is not a barrier that prevents pathogens from entering the body? Lysozyme. Mucus. Antigens. Ear wax

Antigens Antigens are foreign molecules that initiate an immune response.

Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____. macrophages ... B cells and T cells helper T cells ... plasma cells B cells ... macrophages T cells ... B cells B cells ... plasma cells and memory cells

B cells ... plasma cells and memory cells The antigen-selected proliferation of B cells produces clones of plasma cells and memory cells

What is the role of recombinase in generating lymphocyte diversity?

Early in B cell development, recombinase links one light-chain V gene segment to one J gene segment. Early in B cell development, an enzyme complex called recombinase links one light-chain V gene segment to one J gene, rearranging the DNA to assemble a functional Ig gene. Read about the generation of lymphocyte diversity and the role of recombinase.

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.

_____ interact with the antigen-class II MHC complex presented by macrophages. Bacterial cells Helper T cells Epithelial cells Cytotoxic T cells B cells

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.

Vertebrate immune cells, which are phagocytic, include ________. I) neutrophils II) macrophages III) dendritic cells IV) natural killer cells

I, II, and III

Which of the following statements are fundamental to the clonal-selection theory of how the adaptive immune system functions? I) Each lymphocyte has a unique membrane receptor that recognizes one antigen. II) When the lymphocyte binds an antigen, it is activated and begins dividing to form many identical copies of itself. III) Cloned lymphocytes have slight differences and are selected by the spleen for removal if they do not bind an antigen. IV) Cloned cells descend from an activated lymphocyte and persist even after the pathogen is eliminated.

I, II, and IV.

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 are leukocytes that can engulf and digest a pathogen.

Which of these cells is a phagocytic leukocyte that can engulf a foreign bacterium? cytotoxic T cell helper T cell B cell macrophage plasma cell

Macrophages are phagocytic leukocytes.

A certain cell type has existed in the blood and tissue of its vertebrate host's immune system for over 20 years. One day, it recognizes a newly arrived antigen and binds to it, subsequently triggering a secondary immune response in the body. Which of the following cell types most accurately describes this cell?

Memory cell

The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response. perforin ... cell-mediated antibodies ... humoral perforin ... humoral interleukin-2 ... humoral antibodies ... antibody-mediated

Perforin .... cell-mediated Perforin causes the lysis of pathogen-infected body cells; it is a component of the cell-mediated immune response.

B cells that have been stimulated by interleukin-2 develop into _____. helper T cells antigens macrophages plasma cells cytotoxic T cells

Plasma Cells Plasma cells develop from B cells that have been stimulated by the interleukin-2 secreted by helper T cells.

Which of these cells produce and secrete antibodies? plasma cells helper T cells macrophages cytotoxic T cells bacterial cells

Plasma cells Plasma cells are clones of antibody-secreting B cells.

Which of the following events 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.

Which of the following statements best describes the role of mast cells in the inflammatory response?

They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream. Mast cells release chemicals that dilate nearby capillaries, increasing their permeability and allowing blood components to enter the region from the bloodstream, thus causing localized swelling.

Lymphocytes mature in the _____. I) spleen II) thymus III) bone marrow

Thymus and Bone marrow

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 of the following is the best definition of autoimmune disease?

a condition in which self molecules are treated as nonself (loss of self-tolerance)

Clonal selection is an explanation for how ________.

an antigen can provoke production of high amounts of specific antibodies

A patient complaining of watery, itchy eyes and sneezing after being given a flower bouquet as a birthday gift should first be treated with _____.

antihistamines

The role of active cytotoxic T cells is to attack _____.

body cells that have been infected. Nonspecific defense includes natural killer cells that destroy virus-infected body cells, and abnormal cells that could form tumors. Cytotoxic (killer) T lymphocytes kill cancer cells and cells infected by viruses or other intracellular pathogens.

Helper T cells are part of _____.

cell-mediated immune responses. Cell-mediated immunity depends on the activation of T lymphocytes.

Which of the following components of the immune system destroys bacteria by punching holes in the wall of the bacteria? major histocompatibility complex proteins macrophages complement protein plasma cells

complement proteins

T cells of the immune system include _____. cytotoxic and helper cells lymphocytes, macrophages, and dendritic cells plasma, antigen-presenting, and memory cells CD4, CD8, and plasma cells

cytotoxic and helper cells

Acidity in human sweat is an example of _____.

innate immunity

An antigen _____.

is a foreign molecule that evokes a specific response by a lymphocyte. Antigen molecules can be a part of any type of organism. Antigen molecules could also be a part of a product of an organism such as pollen or feces.

Innate immunity ________.

is the first, and most general, mechanism of protection against pathogens

The cells and signaling molecules involved in the initial stages of the inflammatory response are ________.

mast cells and histamines

Which of these cells is responsible for the rapidity of the secondary immune response? cytotoxic T cells cytokines plasma cells memory cells macrophages

memory cells Memory cells are responsible for the rapidity of the secondary immune response and for long-term immunity.

A primary reason for needing a new vaccine for influenza each year is that __

mutation in the influenza virus is frequent. The virus that causes one year's flu outbreak has a high rate of mutation, resulting in antigenic variation that the immune system cannot recognize.

The fact that there are about a million different antigen receptors possible in human B cells is based on _____.

recombination of the segments of the receptor DNA that make up the functional receptor genes. Which variable and which joining segments are recombined in the DNA of the differentiated B cells determine which receptor proteins will be made in that B cellf differentiated B cells.

Immunological memory accounts for ________.

the ancient observation that someone who had recovered from the plague could safely care for those newly diseased

For the successful development of a vaccine to be used against a pathogen, it is necessary that ________.

the surface antigens of the pathogen stay the same

Cell-mediated immunity differs from humoral immunity in that _____

they respond differently to invaders Humoral immunity is a function of B cells and antibody production, whereas cell-mediated immunity is a function of the activation of cytotoxic T cells.