Color textbook of histology 3rd edition gartner test bank by james.pitts293

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Gartner & Hiatt: Color Textbook of Histology, 3rd Edition

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Chapter 12 – Lymphoid (Immune) System

MULTIPLE CHOICE 1. The innate immune system relies on

a. natural killer cells b. T helper cells c. T killer cells d. B memory cells e. B effector cells

Explanation: The answer is a. The innate immune system relies on natural killer cells, macrophages, neutrophils, and complement and Toll-like receptors. T cells and B cells belong to the adaptive immune system.

2. The adaptive immune system relies on

a. natural killer cells b. T helper cells c. neutrophils d. macrophages e. complement

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The answer is b. The adaptive immune system relies on T cells and B cells. The innate immune system relies on natural killer cells, macrophages, neutrophils, and complement and Toll-like receptors.

3. Which of the following relates to the innate immune system?

a. it is slower than the adaptive immune system b. it has immunologic memory c. it exhibits specificity d. it depends on Toll-like receptors e. it has diversity

Explanation: The answer is d. The innate immune system relies on Toll-like receptors for initiating inflammatory and immune responses. The adaptive immune system is slower acting, has immunologic memory, exhibits specificity, and has diversity.

4. A child 6 years of age sees his pediatrician for repeated infections and developing blood in his diarrhea. The physician orders a complete blood count, and the results show very low platelet count and a low lymphocyte levels. Because the little boy also has eczema, the pediatrician suspects WiskottAldrich syndrome. Children with this disease

a. have high T cell count and low B cell count b. high B cell count and low T cell count c. high T cell count and high B cell count d. low T cell count and low B cell count e. high erythrocyte count

Explanation: The answer is d. Children with Wiskott-Aldrich syndrome have low T and B cell counts. They are at very high risk for infection and they usually do not survive into their teens. Many of those who reach their teenage years succumb to leukemia or lymphoma or other cancers. Because their T and B cell counts are

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very low, these children are prone to respiratory infections and are also easy targets for viral, fungal, and bacterial infections. Only boys are susceptible to Wiskott-Aldrich syndrome.

5. Which of the following is a primary (central) lymphoid organ?

a. thymus b. lymph node c. spleen d. pharyngeal tonsil e. palatine tonsil

Explanation: The answer is a. The thymus and bone marrow are the two primary lymphoid organs because it is in those two regions that T cells and B cells, respectively, become immunocompetent. After the lymphocytes become immunocompetent, they migrate to the secondary (peripheral) lymphoid organs: the lymph nodes, diffuse lymphoid tissues, tonsils, and spleen.

6. Clonal expansion is dependent on which of the following cells?

a. effector cells b. plasma cells c. memory cells d. virgin cells e. naïve cells

Explanation: The answer is c. Memory cells undergo cell division after first exposure to an antigen, so that the number of memory cells in that particular clone is increased. Because of the presence of an expanded population of memory cells with an increased affinity for the antigen, subsequent exposure to the same antigen induces a secondary (anamnestic) response that is much faster, more potent, and longer lasting than the primary response. Effector cells are responsive to the antigenic challenge, and plasma cells manufacture

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antibodies. Virgin cells (also known as naïve cells) are B and T cells that have not yet been exposed to antigens. None of these cells are responsible for clonal expansion.

7. Graves’ disease is an autoimmune disorder in which the person forms antibodies against his or her

a. thyroid-stimulating hormone (TSH) b. thyroxine c. thyroid gland d. parathyroid gland e. TSH receptors

Explanation: The answer is e. Patients with Graves’ disease form antibodies against the TSH receptors of their own follicular cells. These persons produce excess thyroid hormone and therefore have an enlarged thyroid gland and exophthalmos (protruding eyeballs). They do not form antibodies against their TSH or against thyroxine. Their thyroid and parathyroid glands are not perceived to be antigens.

8. The membrane attack system is the body’s innate defense system against microbial attack. Which of the following components of the complement system plays a key role in this defense?

a. C2 b. C3 c. C4 d. Factor B e. Factor D

Explanation: The answer is b. C3 plays a key role in the complement system, because deficiency of this protein leads to recurring bacterial infection. C3 can directly activate complement by its interaction with bacteria or even bacterial toxins. C2 and C4 deficiency can result in an autoimmune disease. Factors B and D are responsible for initiating the alternative pathway.

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9. A patient is producing an antibody isotype that is composed of a dimer held together by J protein and is secreted into his saliva. Which of the following isotypes is being produced by this patient?

a. IgA b. IgD c. IgE d. IgG e. IgM

Explanation: The answer is a. IgA, also known as the secretory antibody, is composed of a dimer that is held together by a J protein. IgA is secreted into the gut lumen, saliva, tears, milk, nasal mucus, and the vagina. IgD is a surface immunoglobulin that B cells secrete onto their own cell surface. IgE is the reaginic antibody and is present on the surface of mast cells and basophils. Cross-linking of IgE by antigens on basophils and mast cells facilitates the release of pharmacologic agents from these cells. IgG crosses the placenta and is secreted into milk; it protects the fetus and the neonate by providing them with passive immunity. It is also responsible for antibody-dependent cell-mediated cytotoxicity by activating natural killer cells. IgM is a pentameric form of the antibody and is the first isotype to be formed during a primary response.

10. Which of the following cells possesses CD8 molecules?

a. TH0 b. TH1 c. TH2 d. T reg e. CTL

Explanation: The answer is e. CTLs (cytotoxic lymphocytes; T killer cells) possess CD8 molecules on their surface, and they can interact with major histocompatibility complex I (MHCI) molecules on virally altered cells. If their T-cell receptors recognize the epitopes displayed by the MHCI molecule on these virally altered cells, then the cytotoxic T lymphocyte kills that cell. All T-helper cells and T reg cells possess CD4

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molecules on their cell surfaces, and they can recognize MHCII molecules located on antigen-presenting cells and B cells.

11. Thymic corpuscles (Hassall corpuscles) are composed of

a. type I reticular cells b. type III reticular cells c. type IV reticular cells d. type V reticular cells e. type VI reticular cells

Explanation: The answer is e. Type VI reticular cells compose thymic corpuscles. Type I and type III reticular cells are located in the thymic cortex. Type I cells are responsible for the formation of the blood-thymus barrier, whereas type II reticular cells subdivide the thymic cortex into lymphocyte-filled compartments. Type IV reticular cells are found in close association with type III reticular cells, and they form the corticomedullary junction. Type V reticular cells form the cytoreticulum of the medulla.

12. The marginal zone belongs to which of the following structures?

a. lymph node b. lymphoid nodule c. spleen d. thymus e. pharyngeal tonsil

Explanation: The answer is c. The marginal zone is the interface between the white pulp and the red pulp of the spleen and is the first place in the spleen where antigens are permitted to interact with the parenchyma of the spleen.

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13. The region inside the circle is the

a. cortex of a lymph node b. medulla of a lymph node c. cortex of the thymus d. medulla of the thymus e. white pulp of the spleen

Explanation: The answer is e. The region delineated by the circle is the white pulp of the spleen, as is evident by the surrounding red pulp and the dense, irregular collagenous connective tissue capsule that sends trabeculae into the substance of this organ. Lymph nodes are usually surrounded by fat, and in the cortex a subcapsular sinus and cortical lymph nodules would be evident. The medulla of the lymph nodes has no lymphoid nodules, and medullary cords and medullary sinuses would be present. The thymic cortex and the thymic medulla have no lymphoid nodules. Copyright © 2007 by Saunders, an imprint of Elsevier, Inc.

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14. This photomicrograph represents the

a. cortex of a lymph node b. medulla of a lymph node c. cortex of the thymus d. medulla of the thymus e. white pulp of the spleen

Explanation: The answer is b. This photomicrograph represents the medulla of a lymph node, as is evident by the presence of the medullary cords, medullary sinuses, and trabecula and the absence of the cortical lymphoid nodules. The cortex of the thymus has dense accumulations of thymocytes, and the medulla of

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the thymus is dominated by Hassall corpuscles (thymic corpuscles). The white pulp of the spleen has lymphoid nodules and periarterial lymphatic sheaths.